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Publisher: Elsevier   (Total: 3183 journals)

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Showing 1 - 200 of 3183 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 37, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 25, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 101, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 27, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 38, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 5)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 7)
Acta Astronautica     Hybrid Journal   (Followers: 434, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 27, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 297, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 25, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 17, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 11, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 178, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 12, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 16, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 29, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 11, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 11, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 33, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 28, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 26, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 15)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 13)
Advances in Digestive Medicine     Open Access   (Followers: 12)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 29, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 49, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 65, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 20, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 10, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 25, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 3, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 20, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 12, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 7, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 25, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 17)
Advances in Pharmacology     Full-text available via subscription   (Followers: 16, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 65)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 1, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 420, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 36, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 53, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 374, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 11, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 468, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 17, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 44, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 6, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 11)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 10, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 53, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 58, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 63, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 45, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 12)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 35, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 35, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 50)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 242, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 30, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 28, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 65, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 23, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 5, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 207, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 211, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 6, SJR: 0.937, CiteScore: 2)
Animal Reproduction Science     Hybrid Journal   (Followers: 7, SJR: 0.704, CiteScore: 2)

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Similar Journals
Journal Cover
Advances in Water Resources
Journal Prestige (SJR): 1.551
Citation Impact (citeScore): 3
Number of Followers: 53  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0309-1708
Published by Elsevier Homepage  [3183 journals]
  • Pore-network modelling of non-Darcy flow through heterogeneous porous
    • Abstract: Publication date: Available online 10 July 2019Source: Advances in Water ResourcesAuthor(s): A.A. El-Zehairy, M. Mousavi Nezhad, V. Joekar-Niasar, I. Guymer, N. Kourra, M.A. Williams A pore-network model (PNM) was developed to simulate non-Darcy flow through porous media. This paper investigates the impact of micro-scale heterogeneity of porous media on the inertial flow using pore-network modelling based on micro X-ray Computed Tomography (XCT) data. Laboratory experiments were carried out on a packed glass spheres sample at flow rates from 0.001 to 0.1 l/s. A pore-network was extracted from the 3D XCT scanned volume of the 50 mm diameter sample to verify the reliability of the model. The validated model was used to evaluate the role of micro-heterogeneity in natural rocks samples. The model was also used to investigate the effect of pore heterogeneity on the onset of the non-Darcy flow regime, and to estimate values of the Darcy permeability, Forchheimer coefficient and apparent permeability of the porous media. The numerical results show that the Reynold's number at which nonlinear flow occurs, is up to several orders of magnitude smaller for the heterogeneous porous domain in comparison with that for the homogeneous porous media. For the Estaillades carbonate rock sample, which has a high degree of heterogeneity, the resulting pressure distribution showed that the sample is composed of different zones, poorly connected to each other. The pressure values within each zone are nearly equal and this creates a number of stagnant zones within the sample and reduces the effective area for fluid flow. Consequently, the velocity distribution within the sample ranges from low, in stagnant zones, to high, at the connection between zones, where the inertial effects can be observed at a low pressure gradient.
  • Seasonal and event-based concentration-discharge relationships to identify
           catchment controls on nutrient export regimes
    • Abstract: Publication date: Available online 10 July 2019Source: Advances in Water ResourcesAuthor(s): Camille Minaudo, Rémi Dupas, Chantal Gascuel-Odoux, Vincent Roubeix, Pierre-Alain Danis, Florentina Moatar The analysis of concentration-discharge (C-Q) relationships provides useful information on the processes controlling the mobilization and delivery of chemical elements into streams as well as biogeochemical transformations in river networks. Previous metrics developed to characterize export regimes seldom considered the possibility for the C response to Q dynamics to differ between short-term Q variations during storm events and seasonal Q variations during baseflow periods. Here, we present the “C-Qquick-slow” model, which considers the possibility for C-Q relationships to vary across temporal scales. This model was applied in 219 French catchments with various sizes (11 – 2500 km²), land use and hydrological contexts. We evidenced contrasting export regimes for nitrate (NO3−), total phosphorus (TP) and soluble reactive phosphorus (SRP), and surprisingly consistent C-Q patterns at the seasonal scale for each parameter. For instance, NO3−-Q relationships were positive at the seasonal scale in 75% cases and relationships during storms showed either a dilution pattern (24% cases), a non-significant pattern (50%), or a mobilization pattern (12%). TP and SRP relationships with Q at the seasonal scale were almost systematically negative (95%), and patterns during storm events were in most cases mobilization for TP (77%) or non-significant for SRP (69%). We linked the different C-Q relationships with catchment descriptors and found that indicators of diffuse source loading determined NO3− seasonal amplitudes, and hydrological drivers could explain the behavior during storms. By contrast, point sources determined P seasonal amplitudes, and diffuse sources controlled P dynamics during storms. The C-Qquick-slow model has the potential to improve nutrient load estimations because of the good predictability of appropriate C-Q archetypes and the possibility to interpolate low frequency concentration data to a daily frequency.
  • A Coupled Surface Water Storage and Subsurface Water Dynamics Model in
           SWAT for Characterizing Hydroperiod of Geographically Isolated Wetlands
    • Abstract: Publication date: Available online 10 July 2019Source: Advances in Water ResourcesAuthor(s): Junyu Qi, Xuesong Zhang, Sangchul Lee, Glenn E. Moglen, Ali M. Sadeghid Gregory W. McCarty Wetlands play an important role in watershed hydrology and biogeochemistry. A geographically isolated wetland (GIW) module for Soil and Water Assessment Tool (SWAT) was developed to couple surface water storage and subsurface water dynamics to characterize hydroperiod. The new GIW module includes the following features: (1) a flexible geometric formula to characterize wetland surface water area, volume, and depth; (2) a revised algorithm to account for evaporation from both water and soil surfaces in wetlands; (3) application of the Richards equation to couple surface water storage and subsurface water dynamics; (4) use of Darcy's law with an effective hydraulic conductivity parameter to simulate groundwater discharge. We tested the GIW module using observed daily water level data from four wetlands at two sites (including restored and natural wetlands with and without a low-permeability soil layer) in the Delmarva Peninsula, USA. The results show that the wetland module reasonably reproduced observed water levels for both restored and natural wetlands with and without a low-permeability soil layer. The module was also able to reasonably simulate saturated and unsaturated portions of the soil corresponding to wet and dry periods. The ability of the GIW module to describe inundation conditions for wetlands holds promise to enhance the understanding and quantification of hydrological and biogeochemical roles of GIWs in a watershed context.
  • Experimental analysis of wave attenuation and drag forces in a realistic
           fringe Rhizophora mangrove forest
    • Abstract: Publication date: Available online 10 July 2019Source: Advances in Water ResourcesAuthor(s): Maria Maza, Javier L. Lara, Iñigo J. Losada With the aim of better understand and parameterize the physical processes involved in flow-mangrove interaction, wave attenuation and drag forces along a 1:6 scale fringe Rhizophora mangrove forest are studied experimentally. The 26 m long forest is composed by 135 models built reproducing mature Rhizophora mangrove trees with 24 prop roots. Hydrodynamic conditions are scaled using Froude similarity based on values collected in nature. Regular and random waves are tested and three water depths are considered to account for the influence of variable mangroves frontal area along the vertical. Wave decay analysis highlights the importance of considering the effect of flume bottom and walls friction. Neglecting this additional damping can result in a high overestimation of the mangrove dissipation capacity. It is proven that water depth, and the associated mangroves frontal area, and wave height are the dominant variables driving wave attenuation for short waves. The slope seaward the forest induces wave shoaling leading to an increase of wave steepness. Accordingly, the exerted forces on the mangroves also increase along the first 3 – 4 m of the forest. Smaller forces are recorded further into the forest where wave decay formulations fit well to the recorded wave heights. In general, analytical drag forces obtained by using mangrove trees induced damping coefficients compare well to the forces measured within the forest. However, analytical drag forces can lead to overestimations of up to double in some cases. This aspect is very important when experimental results are used to feed numerical or analytical models based on the introduction of a drag force in the momentum equation. These models should be calibrated using, whenever possible, direct force measurements.
  • Seasonal predictability of high sea level frequency using ENSO patterns
           along the U.S. West Coast
    • Abstract: Publication date: Available online 9 July 2019Source: Advances in Water ResourcesAuthor(s): Abdou Khouakhi, Gabriele Villarini, Wei Zhang, Louise J. Slater High sea levels can be conducive to coastal flooding, coastal erosion and inland salt-water intrusion, and thus pose a significant threat to coastal communities, ecosystems and coastal assets. Increases in high water levels have been attributed largely to rising mean sea levels associated with intra-seasonal to interannual climate modes of variability such as the El Niño-Southern Oscillation (ENSO). Here, we examine the predictability of the seasonal frequency of high sea levels using the Niño3.4 index. Different high sea level quantities are considered at 23 tide gauges along the U.S. West Coast, including storm surge and nuisance (minor) floods. At each site, we develop a statistical probabilistic forecasting model for seasonal high sea level frequency during the cold period of October-March. As predictors, we compare the use of (1) seasonal Niño3.4 index observations over the warm antecedent period of July-September and (2) seasonal Niño3.4 index forecasts from the North American Multi-Model Ensemble (NMME) over the cold concurrent period of October-March. Results indicate that the Niño3.4 observations are a good predictor of seasonal high sea level frequency, especially for predicting the storm surge frequency. Correlation coefficients between the observed and modelled seasonal storm surge frequency range from 0.6 to 0.95 at most of the 23 tide gauges. In the predictive model, when using NMME Niño3.4 index, correlation coefficients range between approximately 0.4 and 0.7 at the southern gauges for Niño3.4 index forecasts initialized from October to June (the skill decreases with lead time). Our results provide insights into the seasonal predictability of high sea levels using ENSO patterns which is important for planning and coastal management.
  • Optimal impoundment operation for cascade reservoirs coupling parallel
    • Abstract: Publication date: Available online 8 July 2019Source: Advances in Water ResourcesAuthor(s): Shaokun He, Shenglian Guo, Kebing Chen, Lele Deng, Zhen Liao, Feng Xiong, Jiabo Yin The optimal impoundment operation of cascade reservoirs can dramatically improve the utilization of water resources. However, their complex non-convexity and computational costs pose challenges to optimal hydroelectricity output and limit further development of joint operation within larger-scale cascade reservoirs. In recent decades, parallel dynamic programming (PDP) has emerged as a means of alleviating the ‘curse of dimensionality’ in the mid-long term reservoir operation with more involved computing processors. But it still can't effectively solve the daily impoundment operation of more than three reservoirs. Here, we propose a novel method called importance sampling-PDP (IS-PDP) algorithm in which the merits of PDP are integrated with importance sampling and successive approximation strategy. Importance sampling is first used to construct the state vectors of each period by introducing ‘Manhattan distance’ in the discrete state space. Then the PDP recursive equation is used to find an improved solution during the iteration. The IS-PDP method is tested to optimize hydropower output for the joint operation of an 11-reservoir system located in the upper Yangtze River basin of China after establishing impoundment operation by advancing impoundment timings and rising water levels. We find that our methodology could effectively deal with the ‘curse of dimensionality’ for such mega reservoir systems and make better use of water resources in comparison to the Standard Operation Policy (SOP). Given its computational efficiency and robust convergence, the methodology is an attractive alternative for non-convex operation of large-scale cascade reservoirs.
  • Anisotropic dispersion with a consistent smoothed particle hydrodynamics
    • Abstract: Publication date: Available online 5 July 2019Source: Advances in Water ResourcesAuthor(s): Carlos E. Alvarado-Rodríguez, Leonardo Di G. Sigalotti, Jaime Klapp A consistent smoothed particle hydrodynamics (SPH) approach is used to simulate the anisotropic dispersion of a solute in porous media. Consistency demands using large numbers of neighbors with increasing resolution. The method is tested against the anisotropic dispersion of a Gaussian contaminant plume. With irregularly distributed particles, the solution for isotropic dispersion converges to second-order accuracy when at sufficiently high resolution a large number of neighbors is used within the kernel support. For low to moderate anisotropy, the convergence rates are close to second-order, while for large anisotropic dispersion the solutions converge to better than first-order. For randomly distributed particles, the solutions are also better than first order independently of the degree of anisotropy. When negative concentrations arise, they are several orders of magnitude smaller than those encountered with standard SPH and comparable to those obtained with the MWSPH scheme of Avesani et al. The method is also insensitive to particle disorder and achieves an overall accuracy comparable to the MWSPH method using a much simpler approach.
  • Improved dynamic programming for parallel reservoir system operation
    • Abstract: Publication date: Available online 4 July 2019Source: Advances in Water ResourcesAuthor(s): Xiang Zeng, Tiesong Hu, Ximing Cai, Yuliang Zhou, Xin Wang Optimizing a multi-reservoir system is challenging due to the problem of the curse of dimensionality. In this paper, rule-based improved dynamic programming (RIDP) and stochastic dynamic programming (RISDP) algorithms for the optimal operation of a system with a number of parallel reservoirs are proposed to alleviate the dimensionality problem. The improvement is based on a key property: the monotonic dependence relationship between individual reservoir carryover storage and system water availability, which is derived with the assumption of the non-decreasing storage distribution characteristic of a parallel reservoir system. Furthermore, a diagnosis procedure is employed to remove infeasible state transitions, which enables the application of the monotonic relationship within the feasible solution space. In general, the computational complexity of (NS)n2 from DP can be reduced to (NS)n from RIDP (NS is the number of storage discretization for individual reservoirs, n is the number of reservoirs in a parallel system), with controlled solution accuracy. The improved algorithms are applied to a real-world parallel reservoir system in northeastern China. The results demonstrate the computational efficiency and effectiveness of RIDP and RISDP.
  • nModeling of 2-D Seepage From Aquifer Towards Stream via Clogged Bed: the
           Toth-Trefftz Legacy Conjugated
    • Abstract: Publication date: Available online 3 July 2019Source: Advances in Water ResourcesAuthor(s): A.R. Kacimov, Yu. V. Obnosov Baseflow-type interaction between a river and adjacent/subjacent aquifer across a thin clogging layer of fine sediments controls the dynamics of surface-pore water resources, quality of both waters, seepage induced erosion of the river bed and other hydrological phenomena. Transient 2D phreatic flow from an unconfined aquifer into a river with a thin low-permeable cake (hydraulic skin) is approximated by a sequence of steady states, each of which assumes the water table to be horizontal. The scalar and vector fields of piezometric head, stream function and Darcian velocity are found from analytical solution of the Dirichlet and Robin (linear combination of the velocity potential and its normal derivative) boundary value problems for the piezometric head (harmonic function). The time-shrinking Tothian “unit basins” are a half-strip, half-plane or rectangle. Stream banks are assumed to be horizontal or vertical segments. Cross-flow from the aquifer into the stream is controlled by the aquifer-skin conductivity ratio and the stages of the river and adjacent aquifer. The head and cross-flux on the interface (Robin's boundary) is shown to vary along this line and therefore even for vertical river banks the Dupuit-Forchheimer approximation is not strictly valid. Numerical simulations in HYDRUS2D are reasonably close to the analytical results. Early-stage drawdown of a rectangular cake due to a sudden drop of the water level on the river side and formation of a seepage face is analysed with potential applications to stability of earth dams.
  • Characterizing and modeling subnational virtual water networks of US
           agricultural and industrial commodity flows
    • Abstract: Publication date: Available online 3 July 2019Source: Advances in Water ResourcesAuthor(s): Susana Garcia, Alfonso Mejia Virtual water flows have been extensively analyzed at the national level using complex network approaches. However, less is known about the regional structure of subnational virtual water flows, even though virtual water flows can vary greatly within a country. Additionally, subnational-level studies are needed since water policy and decision-making tend to be local or regional in scope. Here, we characterize and model virtual water flows for aggregated agricultural and industrial commodities at the US subnational level. Using subnational trade data for the US, we build and analyze unweighted and weighted, directed virtual water trade networks (VWTNs). To model and explore the drivers of subnational virtual water flows, we build and implement a gravity-type spatial interaction model. Using different network metrics, we find that the subnational VWTNs differ from previous well-studied networks, including national-level VWTNs. The network metrics also show a high connectivity for the unweighted VWTNs with no community structure, while the weighted VWTNs reveal spatially coherent communities of intense trade activity. The gravity model shows that the subnational weighted VWTNs are mainly controlled by distance, agricultural land, gross domestic product, and population. Despite the high connectivity of the VWTNs, the presence of community structure indicates that large volumes of virtual water are traded regionally. This suggests the possibility of having hydroeconomic boundaries that differ from known physical boundaries, e.g., watersheds and aquifers. Such boundaries could have implications for the design of consumption-based strategies for water sustainability.
  • Quantile-based downscaling of rainfall extremes: Notes on methodological
           functionality, associated uncertainty and application in practice
    • Abstract: Publication date: Available online 2 July 2019Source: Advances in Water ResourcesAuthor(s): Elmira Hassanzadeh, Ali Nazemi, Jan Adamowski, Truong-Huy Nguyen, Van-Thanh Van-Nguyen Local characteristics of extreme rainfall quantiles, manifested through Intensity-Duration-Frequency (IDF) curves, are key to infrastructure design. Due to climate change, rainfall extremes are subject to changes, it is, therefore, crucial to explore the potential impacts these changes will have on design storms. A new strain of methodologies, quantile-based downscaling approaches, have recently been proposed to exclusively downscale extreme rainfall quantiles obtained from Global Climate Models (GCMs). These approaches, however, have not been systematically intercompared and the uncertainties related to assigning future design storms are poorly understood. This study evaluates the functionality of three quantile-based downscaling methods during the historical and future periods in Montreal, Canada. Results show that the performance of quantile-based downscaling approaches in reproducing observed extreme quantiles can be divergent. At lower return periods, however, differences between the three schemes are not significant. Similar performances for reproducing historical rainfall extremes, however, does not necessarily imply similar future projections due to the different functionalities of the three approaches in mapping GCM projections into finer scales. Despite these uncertainties, the total projection range of future rainfall extremes are, in many cases, comparable to the confidence interval of the parametric probability distribution when fitted to the observed annual maximum rainfall series. A risk-based approach to accommodate this uncertainty in vulnerability assessments through evaluating potential alterations in historical rainfall extremes using an ensemble projection coming from multiple downscaling approaches is suggested. This allows for the selection of design storms based on the acceptable level of risk and given budgetary and operational restrictions.
  • Mechanistic Model of Multi-Frequency Complex Conductivity of Porous Media
           Containing Water-Wet Nonconductive and Conductive Particles at Various
           Water Saturations
    • Abstract: Publication date: Available online 28 June 2019Source: Advances in Water ResourcesAuthor(s): Yuteng Jin, Siddharth Misra, Dean Homan, John Rasmus, André Revil Electrically conductive particles, such as pyrites, and surface-charge-bearing nonconductive particles, such as clays, are commonly present in water-bearing subsurface formations. Under an external electric field generated by electromagnetic measurement tool, these particles give rise to interfacial polarization (IFP) effects, which causes frequency dispersion of effective conductivity and effective permittivity of the mixture containing such particles. The neglect of IFP effects can lead to inaccurate estimation of petrophysical properties of formations, especially in clay- and pyrite- rich formations. In this paper, we developed a mechanistic model that couples surface-conductance-assisted interfacial polarization (SCAIP) model with perfectly polarized interfacial polarization (PPIP) model to estimate effective conductivity and effective permittivity of homogeneous formations containing both nonconductive and conductive particles at various fluids saturations. The model is developed based on the Poisson-Nernst-Planck (PNP) equations for a dilute solution in a weak electrical field regime to calculate the dipolarizability of the representative volume comprising a single isolated spherical particle in an electrolyte host. Then the effective medium theory is used to determine effective complex conductivity of the whole mixture. The result shows that the conductive particles dominate the frequency dispersion of complex conductivity due to IFP effects compared to nonconductive particles.
  • On Information Coupling in Hybrid ISPH Framework for Fluidized Granular
    • Abstract: Publication date: Available online 26 June 2019Source: Advances in Water ResourcesAuthor(s): Gourabananda Pahar, Anirban Dhar An improved information transfer mechanism is developed to couple fluid and granular modules for Incompressible Smoothed Particle Hydrodynamics modelling of sediment transport. The interaction force pair necessitates effective projection of information among parallel continuum based modules. The particle position in either module is susceptible to considerable variation due to their Lagrangian nature. An attempt has been made to minimize the effective thickness of the diffused interface between the fluid and granular particles. The proposed model reduces artificial drag force resulting from diffused computation of effective porosity. The revised framework outperforms in coarse resolution compared to its existing counterpart.
  • Relational analysis of the resource nexus in arid land crop production
    • Abstract: Publication date: Available online 26 June 2019Source: Advances in Water ResourcesAuthor(s): Violeta Cabello, Ansel Renner, Mario Giampietro While a large number of descriptive studies have delineated the interlinkages between water, food and energy resources in the last decade, there is still need for systematic conceptualization of resource nexus interconnections. This paper proposes a theory of relational analysis of the nexus based on the analytical concept of nexus networks. A taxonomy of nexus interconnections, detailing sequential and hierarchical connections, is characterized between and amongst the technosphere and biosphere. We illustrate the use of a novel diagnostic tool with regard to its ability to integrate macro-, meso- and microscale drivers of nexus problems. We apply this framework to problems generated by intensive crop production for exportation in an arid landscape (driven by external markets) and sustainable management of water resources (driven by public policies) in a southern Spanish region. We elucidate interconnected causal mechanisms for groundwater overexploitation and profile different social-ecological patterns on a spatially-explicit basis. The proposed approach is capable of accounting for the water-energy-food resource nexus in an integrated and multi-level fashion, addressing the tensions generated by both multi-functionality and resource entanglement in complex social-ecological systems.Graphical Image, graphical abstract
  • Nanoscale confined gas and water multiphase transport in nanoporous shale
           with dual surface wettability
    • Abstract: Publication date: Available online 25 June 2019Source: Advances in Water ResourcesAuthor(s): Wenhui Song, Jun Yao, Dongying Wang, Yang Li, Hai Sun, Yongfei Yang, Lei Zhang Fluid transport in nanoporous shale is known to be affected by the nanoscale fluid transport mechanisms, surface wettability and heterogeneous pore structure. The pores of shale are believed to be dual surface wettability with gas-wet organic pores and water-wet inorganic pores. Investigation on the nanoscale multiphase transport behavior in dual surface wettability nanoporous shale has practical implication in understanding inject water distribution during injected water flow in and flow back process. In this study, we propose a nanoscale gas and water multiphase pore network transport model to study nanoscale confined gas and water transport behavior in dual wettability nanoporous shale. A 3-D shale pore network model is constructed from 3-D image that is reconstructed from 2-D shale SEM image of organic-rich sample. Water transport considers the boundary slip length determined by the contact angle. Bulk gas transport in inorganic pores considers slip effect while bulk gas transport and surface diffusion for adsorbed gas are both considered in organic pores. Injected water flow in process is modeled by water displacing gas process while injected water flow back process is modeled by gas displacing water process. Gas and water relative permeabilities during injected water flow in and flow back process at different TOC volumes and inorganic pore contact angle are analyzed in detail and are compared with relative permeabilities without nanoscale transport mechanisms. Study results reveal that nanoscale gas and water relative permeabilities are influenced by the total organic carbon (TOC) in volumes and inorganic pore water contact angle while nanoscale transport mechanisms influence on the relative permeabilities can be neglected.
  • A numerical framework for two-phase flow of CO2 injection into the
           fractured water-saturated reservoirs
    • Abstract: Publication date: Available online 22 June 2019Source: Advances in Water ResourcesAuthor(s): Raheel Ahmed, Jun Li We present a novel numerical framework for the simulation of compositional compressible gas-water phase flow in fractured porous media based on a fully-implicit cell-centred finite-volume method on unstructured grids. We employ discrete-fracture model where fractures are modelled lower-dimensionally, within a rock matrix. A mass balance equation is solved over rock-matrix while a lower-dimensional flow equation is solved over lower-dimensional fractures, with coupling terms to account for the flux transfer from the surrounding rock-matrix. The discretisation of the Darcy-fluxes is based on control-volume distributed multi-point flux approximation (CVD-MPFA) coupled with lower-dimensional fracture model. We solve a non-linear system for the primary variables that are the phase pressure and the component molar densities while secondary variables are updated depending on the updated values of primary variables at each iteration of the non-linear solver. We use the cubic type equation-of-state (EOS) to model the physical properties of the gas components, e.g. CO2. The water phase is multi-component as we allow solubility of gas component in water phase. Solubility of H2O in gaseous phase is also included in the developed method. We compare compositional simulation results, using unstructured grids, obtained via the lower-dimensional fracture model and the results obtained by the equi-dimensional fracture model for the case of CO2 injection into aqueous reservoir with intersecting fractures. The results show good agreement between the two models while the lower-dimensional fracture model is also computationally cost effective. Results are also presented for the evolution of injected CO2 under gravity through water saturated reservoir with and without fractures that demonstrate the profound effects of discrete-fractures that can lead to CO2 leakage. The presented method is also applied to a 3D simulation of injection of multi-component gas with CO2 and CH4 into a saline water saturated reservoir with a surface 2D fracture network.
  • Bringing Realism into a Dynamic Copula-based Non-stationary
           Intensity-Duration Model
    • Abstract: Publication date: Available online 22 June 2019Source: Advances in Water ResourcesAuthor(s): R. Vinnarasi, C.T. Dhanya Dynamic behavior of extreme rainfall characteristics heightened by the abrupt warming of the environment has affected the sustainability of the existing water resources systems and infrastructure, which were designed employing the traditional ‘stationary’ assumption. Here, we propose a realistic and efficient framework to detect non-stationarity in the observed hydrologic variables, to overcome a few limitations suffered by the traditional non-stationary approaches. The methodology is demonstrated over the short period rainfall series of four major metropolitan cities of India, where the intensity of the rainfall is reportedly increasing sharply accompanied by the changes in the pattern of rainfall. Since direct runoff is influenced by the intensity and duration of rainfall, it is important to study the joint characteristics of intensity and duration in the context of non-stationarity, especially in urban regions where the relationship is more distinct. Hence, we estimated the time-varying joint return period/return level of its extremes, utilizing a dynamic Bayesian copula. We have implemented time-varying multivariate probability frequency analysis to derive the time-varying Intensity-Duration relationship. Here we employed a Bayesian approach through Differential Evolution Markov Chain (DE-MC) algorithm to estimate the uncertainty bound of the time-varying return level. The results emphasize that the probabilistic distribution parameters vary both temporally and spatially, and recommend the incorporation of non-stationarity in the extreme event modeling, only if there is a change in the probabilistic distribution parameters. This non-stationary model can be seamlessly employed to compute return levels with better accuracy and reliability than traditional stationary/non-stationary methods. We observe that the short duration return level increases at a faster rate than the longer ones, with the credibility interval larger than that of long duration return levels. The results also highlight the importance of adopting event based non-stationary IDF curves for the design of water resource systems and to devise long-term decision-making strategies to address the changing climate. However, we do not draw any conclusion concerning climate change, in general, from the short duration rainfall records used in this study.
  • Equivalence of turbulence statistics between monodisperse and polydisperse
           turbidity currents
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Mrugesh Shringarpure, Mariano I. Cantero, S. Balachandar Turbidity currents are buoyancy driven submarine flows where the source of buoyancy is typically a polydisperse sediment suspension. Sustained propagation of such flows depend on the ability of turbulence in the flow to keep the settling sediments in suspension. Recent studies by Cantero et al. (2012b) and Shringarpure et al. (2012) have investigated the interaction of monodisperse sediment suspension and turbulence in turbidity currents on smooth sloping beds. These studies showed that stable stratification of sediment suspension damps turbulence and in some cases can be fully suppress turbulence. Furthermore, it was shown that the turbulence damping effect of a monodisperse sediment suspension can be quantified by the product of shear Richardson number and the sediment settling velocity. In this study we generalize this result for a polydisperse sediment suspension. We compare the turbulence statistics of turbidity currents driven by different polydisperse suspensions and show that as long as the total amount of sediment and the product of shear Richardson number and effective settling velocity (a value representing the polydisperse suspension) are the same, the turbulent velocity statistics of the different polydisperse suspensions nearly collapse. Furthermore, if the effective settling velocity is chosen to be depth-dependent (a function of height from the bed) then the turbulence statistics involving sediment concentration also collapses between different polydisperse suspensions. These results suggest the possibility of modeling polydisperse currents with an equivalent monodisperse suspension whose total sediment load and depth-dependent settling velocity match those of the polydisperse suspension.
  • A three-phase flow simulation of local scour caused by a submerged wall
           jet with a water-air interface
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Cheng-Hsien Lee, Conghao Xu, Zhenhua Huang Interactions between fluid and hydraulic structures and the resulting bed scouring are complex phenomena that involve three phases: water, air and sediment. This study presents a new rheology-based three-phase flow model that can (i) track the water-air interface in the presence of suspended sediment and (ii) predict the local scour caused by submerged wall jet. A modified volume-of-fluid (VOF) method was used to track the water-air interface, and a modified k-ϵ turbulence model was employed to capture important features of the turbulent flow, including turbulence modulation due to fluid-sediment interaction. The three-phase model was first used to study the sediment transport in open-channel flows in order to evaluate the performance of two models for particle response time, and then employed to simulate the scouring process downstream a submerged wall jet issued from a sluice gate. The simulated bed profiles showed good agreement with the measured. It was demonstrated that the three-phase model could capture important dynamic features such as sediment avalanche.
  • The influence of granular segregation on gravity-driven particle-fluid
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Michele Larcher, James T. Jenkins We phrase and solve boundary-value problems for the segregation of spheres with either equal density and different sizes, or the same size and different densities in flows of a clear fluid driven by gravity over an inclined, erodible bed in a wide channel. We assume that the flow is steady and uniform, collisions between particles dissipate little energy, and the sizes and masses of the particles are not too different. For particles of the same material with diameters that differ by as little as ten per cent, we find that the flow features, such as velocity, granular temperature and solid concentration profiles, are significantly different from those for a flow of a single species with a diameter equal to the average of the two diameters. In particular, the total particle flux of the mixture is significantly larger.
  • Numerical simulation for sediment transport using MPS-DEM coupling model
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Eiji Harada, Hitoshi Gotoh, Hiroyuki Ikari, Abbas Khayyer Interactions between the uprush and backwash waves around a swash zone cause a complex water surface with wave breaking. Infiltration and exfiltration on a permeable beach face produce significant effects on the bottom shear stress. Abrupt changes of the bottom shear stress induced by uprush waves onto a dry bed have a significant impact on the estimation of sediment flux. In order to simulate, with a high degree of accuracy, a violent flow with wave breaking and complex moving bed boundaries along the on-off shore direction, wave motions are solved by using an enhanced particle method based on the MPS (Moving Particle Semi-implicit) method, while the DEM (Discrete Element Method) is used for a movable bed simulation. Consequently, the high potential of a MPS-DEM coupling model to simulate the swash beach process is clearly demonstrated by comparison with previous experimental results. Furthermore, the significance of the seepage flow in the swash beach process is shown with referring the Nielsen's modified Shields number.
  • A depth-averaged two-phase model for fluvial sediment-laden flows over
           erodible beds
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Ji Li, Zhixian Cao, Honglu Qian, Qingquan Liu, Gareth Pender Fluvial sediment-laden flow represents a class of fluid-solid two-phase flows, which typically involve multi grain sizes, interphase and particle-particle interactions, and mass exchange with the bed. However, existing depth-averaged models ignore one or more of these physical aspects. Here a physically enhanced, coupled depth-averaged two-phase model is proposed for fluvial sediment-laden flow, which explicitly incorporates all these aspects and also turbulent Reynolds stresses. A well-balanced numerical algorithm is applied to solve the governing equations of the model. The present model is benchmarked against a series of typical cases, concerning refilling of a dredged trench, bed aggradation due to sediment overloading, and flood flows due to landslide dam failure. It features encouraging performance as compared to measured data and a quasi single-phase mixture model. The present model reveals that the larger the grain size, the slower the sediment fraction transports, which concurs with prior findings from experimental observations and field data. Also, the fluid phase Reynolds stresses are considerable where the flow rapidly varies, whilst the solid phase Reynolds stresses are negligible if sediment concentration is sufficiently low.
  • Wind effect on gyrotactic micro-organism surfacing in free-surface
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Maryam Mashayekhpour, Cristian Marchioli, Salvatore Lovecchio, Ebrahim Nemati Lay, Alfredo Soldati We examine the effect of wind-induced shear on the orientation and distribution of motile micro-swimmers in free-surface turbulence. Winds blowing above the air–water interface can influence the distribution and productivity of motile organisms via the shear generated just below the surface. Swimmer dynamics depend not only on the advection of the fluid but also on external stimuli like nutrient concentration, light, gravity, which are in turn coupled to and influenced by the distribution of the swimmers. Here we focus on gyrotaxis, resulting from the gravitational torque generated by an asymmetric mass distribution within the organism. The combination of such torque with the viscous torque due to shear can reorient swimmers, reducing their vertical migration and causing entrapment in horizontal fluid layers. Through DNS-based Euler–Lagrangian simulations we investigate the effect of wind-induced shear on the motion of gyrotactic swimmers in turbulent open channel flow. We consider different wind forcing and swimmers with different reorientation time (reflecting the ability to react to turbulent fluctuations). We show that only stable (high-gyrotaxis) swimmers may reach the surface and form densely concentrated filaments, the topology of which depends on the wind direction. Otherwise swimmers exhibit weaker vertical fluxes and loose segregation at the surface.
  • Quasi-3D two-phase model for dam-break flow over movable bed based on a
           non-hydrostatic depth-integrated model with a dynamic rough wall law
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Tatsuhiko Uchida, Shoji Fukuoka The assumptions of equilibrium flow conditions neglecting the flow acceleration for vertical velocity distributions and of the equilibrium wall law applied to the bottom boundary condition, in which the flow acceleration is neglected in the vicinity of the bed, are questionable when used to calculate sediment transport for flows that vary rapidly over time and space. Examples of such flows include dam-break flows and flows around structures. This study proposes a two-phase depth-integrated model for large-scale geophysical flow applications involving sediment transport phenomena and bed morphology. The model for the fluid phase is based on the non-hydrostatic quasi-3D method, and uses a dynamic rough wall law that employs continuity and momentum equations for the bottom boundary conditions.It was confirmed that the proposed model reduces to the previous bedload formulae for uniform flow conditions under the weak sediment transport condition. The model was applied in an experiment involving a dam-break flow on a movable bed channel with a suddenly enlarged section. The comparison between the experimental results and the results calculated with the proposed model and previous models demonstrates the validity of the proposed model. The comparison also highlights the advantages of introducing a quasi-3D two-phase model to evaluate vertical velocity distributions and non-equilibrium sediment motions.
  • Interface-resolved large eddy simulations of hyperconcentrated flows using
           spheres and gravel particles
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Tomoo Fukuda, Shoji Fukuoka Interface-resolved large eddy simulations were performed to reproduce hyperconcentrated water-particle mixture flows in a laboratory experiment conducted by Egashira et al. (2001). The flows were simulated at sediment concentrations of 0.196 and 0.444 using spheres and gravel particles. Simulations using gravel with a suitable shape properly reproduced the discharge rates of water and particles as well as the wall-normal distributions of the particle velocities in the experiments. The study involved an examination of the effects of particle shapes and the coefficients of contact forces (coefficients of restitution and friction angles of particle surfaces) used in the discrete element method on mixture flows. Significantly different flows were obtained for spherical and gravel particles under dense conditions, whereby the particle shear stress became much greater than that for water. The simulations of spheres at different coefficients of contact forces could not adequately represent the mixture flows of nonspherical particles.
  • Quantification of spatial lag effect on sediment transport around a
           hydraulic structure using Eulerian–Lagrangian model
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Kazuyuki Ota, Takahiro Sato, Hajime Nakagawa The spatial lag effect on sediment transport around a hydraulic structure is quantified through numerical simulation using a Eulerian–Lagrangian model. The Eulerian–Lagrangian model uses a deterministic approach of bed load motion and stochastic approach of Einstein's concept, which allows for a reasonable quantification of both non-equilibrium and equilibrium bed load transport rates. Numerical simulations are conducted for local scour around a spur dyke and a weir-type structure. As pointed out in previous experimental studies on the one-dimensional problem, Eulerian–Lagrangian simulation reveals an unsaturated bed load in a scour hole around a hydraulic structure. Furthermore, an oversaturated bed load is also found in the deposition region, particularly behind the structure. The validity of the linear adaptation equation is discussed using numerical results, revealing the possibility that the linear adaptation equation does not appropriately represent the existence of the strong spatial lag effect. The present study finds there are two modes in the response of the adaptation length to the unsaturated bed load, which depend on the clear-water scour condition or the live-bed scour condition. Findings of this study will contribute to multi-dimensional sediment transport simulations that consider the spatial lag effect.
  • Wave-induced morphodynamics and sediment transport around a slender
           vertical cylinder
    • Abstract: Publication date: July 2019Source: Advances in Water Resources, Volume 129Author(s): Massimo Miozzi, Sara Corvaro, Francisco Alves Pereira, Maurizio Brocchini We study the dynamics of a sandy bed around a slender vertical cylinder forced by progressive, non-linear water waves. The seabed evolves continuously under the effects of the up-welling, down-welling and rolling events induced by vortical coherent structures. In turn, these are closely connected to the shape of the seabed, which is modified by the scouring and/or the deposition of the sand. Starting from a flat seabed, progressive waves induce a rapid and transient modification of the bottom morphology towards a dynamically stable equilibrium state, which is the focus of this work. The dynamical equilibrium state is a function of the wave period and is reached when the seabed morphology is not substantially altered. We describe such a state by an Eulerian in-phase analysis of the sand particle motion, inferred from Lagrangian data collected over a large number of wave passages. This analysis relies on the use of the defocusing digital PIV technique (DDPIV), for the first time applied to the specific flow of interest here. On the basis of the Eulerian analysis, the triggering of the key-events (up- and down-welling, rolling) over the wave phase is captured by identifying, through the Q > 0 criterion, the coherent flow structures responsible for the events. This analysis is coupled with the description of the sediment trajectories, analyzed in a Lagrangian manner and effectively assessing how and where the solid phase is transported during the key-events. Five main mobilization/transport mechanisms have been identified, three during the onshore flow and two during the offshore flow: (i) generation of a coherent structure reminiscent of a horseshoe vortex at the toe, (ii) intense scouring at the top of the flatbed region, (iii) vortex shedding in the wake during direct (onshore) flow, (iv) shear crossflow on the lee-side of the cylinder and (v) large vertical shearing in the flatbed region during the reverse (offshore) flow. At flow reversal, this shearing mechanism impacts on a significant area of sediments in the incoming region of the flow.
  • Instability analysis of the flow between two parallel plates where the
           bottom one coated with porous media
    • Abstract: Publication date: Available online 15 June 2019Source: Advances in Water ResourcesAuthor(s): Zhenxing Wu, Parisa Mirbod This study investigates the instability of pure Newtonian fluid flow between two parallel plates where the bottom one coated with various porous media with permeability K and porosity ε. We have applied normal modes to perturb the coupled flow system. Specifically, the effects of some dimensionless parameters such as depth ratio, permeability parameter, and the porosity of the porous medium on the instability have been examined. We found these parameters play a critical role in the instability. Depending on these parameters, instability is initiated and dominated either by the fluid or by the porous region. In particular, we found that there are ranges of the depth ratio and the permeability parameter for each value of the porous media porosity that affect the instability of this coupled flow. We have also determined a new parameter which specifies the potential dominance and the stability margin of each mode. To validate our calculations, we have also compared our results with the Orr-Sommerfeld equation. In addition, we have examined three special extreme conditions to study the coupled flow system in more detail.
  • A Generalized Framework for Process-informed Nonstationary Extreme Value
    • Abstract: Publication date: Available online 14 June 2019Source: Advances in Water ResourcesAuthor(s): Elisa Ragno, Amir AghaKouchak, Linyin Cheng, Mojtaba Sadegh Evolving climate conditions and anthropogenic factors, such as CO2 emissions, urbanization and population growth, can cause changes in weather and climate extremes. Most current risk assessment models rely on the assumption of stationarity (i.e., no temporal change in statistics of extremes). Most nonstationary modeling studies focus primarily on changes in extremes over time. Here, we present Process-informed Nonstationary Extreme Value Analysis (ProNEVA) as a generalized tool for incorporating different types of physical drivers (i.e., underlying processes), stationary and nonstationary concepts, and extreme value analysis methods (i.e., annual maxima, peak-over-threshold). ProNEVA builds upon a newly-developed hybrid evolution Markov Chain Monte Carlo (MCMC) approach for numerical parameters estimation and uncertainty assessment. This offers more robust uncertainty estimates of return periods of climatic extremes under both stationary and nonstationary assumptions. ProNEVA is designed as a generalized tool allowing using different types of data and nonstationarity concepts physically-based or purely statistical) into account. In this paper, we show a wide range of applications describing changes in: annual maxima river discharge in response to urbanization, annual maxima sea levels over time, annual maxima temperatures in response to CO2 emissions in the atmosphere, and precipitation with a peak-over-threshold approach. ProNEVA is freely available to the public and includes a user-friendly Graphical User Interface (GUI) to enhance its implementation.
  • Water sorptivity of unsaturated fractured sandstone: fractal modeling and
           neutron radiography experiment
    • Abstract: Publication date: Available online 10 June 2019Source: Advances in Water ResourcesAuthor(s): Yixin Zhao, Yang Wu, Songbai Han, Shanbin Xue, Guowei Fan, Zhongwei Chen, A. El Abd The spontaneous imbibition of water into the matrix and gas-filled fractures of unsaturated porous media is an important phenomenon in many geotechnical applications. Previous studies have focused on the imbibition behavior of water in the matrix, but few works have considered spontaneous imbibition along fractures. In this work, a new fractal model, considering the water losses from the fracture to the matrix, was established to predict the sorptivity of rough-walled fracture. A fractal model, considering the fractal dimension of tortuosity, was modified to estimate the sorptivity of the matrix. Both of the models have a time exponent α and can be simplified to the classical Lucas–Washburn (L–W) equation with α = 0.50. To verify the proposed models, quantitative data on the imbibition of water in both the matrix and the fracture of unsaturated sandstone were acquired by neutron radiography. The results show that the motion of the wetting front in both the matrix and the fracture does not obey the L–W equation. Both theory and experimental observations indicate that fracture can significantly increase spontaneous imbibition in unsaturated sandstone by capillary action. Compared with the classical L–W equation, the models proposed in this study offers a better description of the dynamic imbibition behaviour of water in unsaturated fractured sandstone and, thus, more reliable predictions of the sorptivity of the matrix and the fracture. Moreover, a new method to estimate the time exponent of rough-walled fracture in sandstone was also provided.
  • Multivariate Calibration of Large Scale Hydrologic Models: The Necessity
           and Value of a Pareto Optimal Approach
    • Abstract: Publication date: Available online 9 June 2019Source: Advances in Water ResourcesAuthor(s): Akash Koppa, Mekonnen Gebremichael, William W-G Yeh Multivariate calibration using measurements of multiple water balance components has emerged as a potential solution for improving the performance and realism of large scale hydrologic models. In this study we develop a novel multivariate calibration framework to rigorously test whether incorporation of multiple water balance components into calibration can result in sufficiently accurate (behavioral) solutions for all model responses. Unlike previous studies, we use Bayesian calibration to formally define limits of acceptability or error thresholds in order to distinguish behavioral solutions for each of the incorporated fluxes. We apply the framework in the Mississippi river basin for the calibration of a large scale distributed hydrologic model (Noah-MP) with different combinations of model responses - evapotranspiration (ET), soil moisture (SM), and streamflow (SF). The results of the study show that incorporation of additional fluxes and soil moisture (a storage variable) is not always valuable due to significant trade-offs in accuracy among the model responses. In our experiments, only ET and SF could be simulated simultaneously to a reasonable degree of accuracy. In addition, we quantify the trade-offs in accuracy between the model responses using the concept of Pareto optimality. We find that combining ET with other fluxes entails higher trade-offs in accuracy compared to either SM or SF. Unlike deterministic calibration, with the developed framework we are able to identify deficiencies in model parameterization that lead to significant trade-offs in accuracy, especially between ET and SM. We find that the parameters which are insensitive to individual model responses can influence the trade-off relationship between them.
  • Development and evaluation of a hydrologic data-assimilation scheme for
           short-range flow and inflow forecasts in a data-sparse high-latitude
           region using a distributed model and ensemble Kalman filtering
    • Abstract: Publication date: Available online 8 June 2019Source: Advances in Water ResourcesAuthor(s): Jos Samuel, Alain N Rousseau, Kian Abbasnezhadi, Stéphane Savary A forecasting system combining a physically-based distributed hydrological model (HYDROTEL), an Ensemble Kalman Filtering (EnKF) of Data Assimilation (DA), and forecasted meteorological data (obtained from the North American Ensemble Forecast System; NAEFS) is developed to forecast short-range (0-14 days lead) flows and inflows in the Aishihik and Mayo basins in Yukon Territory, Canada. The system was assessed at three sites, including at the outlet of the Sekulmun River subbasin of the Aishihik basin for river flow forecasting, as well as at Aishihik Lake and Mayo Lake for reservoir inflow forecasting. Model development and evaluation was performed systematically to ensure accuracy of forecasting outputs by: (i) investigating the use of coupled EnKF and HYDROTEL models for improved flow and inflow estimations, (ii) evaluating NAEFS data for short-range flow and inflow forecasts, and (iii) using probabilistic and deterministic criteria to evaluate the forecast performance of the HYDROTEL-EnKF-NAEFS model at each site. Results illustrate DA significantly improve flow and inflow forecasts, and raw NAEFS data need to be spatially and temporally corrected to be used for hydrological forecasts. Based on probabilistic and deterministic scores, it was found that the developed forecasting system can provide flow and inflow forecasts at the Sekulmun River subbasin, Mayo Lake, Aishihik Lake sites with high, medium, and low accuracies, respectively. Differences in forecast accuracies at each site are possibly associated with: (i) uncertainties of forecasted meteorological data, (ii) ability of HYDROTEL to capture daily flow and inflow variation, (iii) DA algorithm used, (iv) heterogeneity in basin attributes, and (v) limited availability of sources of information or data particularly in the lake areas.
  • Characterization of mixing and reaction between chemical species during
           cycles of drainage and imbibition in porous media
    • Abstract: Publication date: Available online 6 June 2019Source: Advances in Water ResourcesAuthor(s): Pei Li, Brian Berkowitz Mixing and reaction between chemical species during cycles of drainage and imbibition in porous media are investigated using a coupled lattice Boltzmann model (LBM). This coupled LBM is able to simulate advection-diffusion processes with homogeneous reactions under dynamic (immiscible) multiphase flow conditions. A feature of the model is that there is no need to track the interface specifically for the transport domain, which improves the computational efficiency significantly. Transport simulations of non-reactive tracers in a natural pore domain show that some tracers can be trapped with the resident wetting fluid, with the tracers in these stagnant regions (defined here as regions where Pé  
  • Numerical Investigation of Viscous Flow Instabilities in Multiphase
           Heterogeneous Porous Media
    • Abstract: Publication date: Available online 5 June 2019Source: Advances in Water ResourcesAuthor(s): K. Christou, W.C. Radünz, B. Lashore, F.B.S. de Oliveira, J.L.M.A. Gomes A critical aspect of multiphase flow in porous media is the displacement efficiency, which measures the amount of fluid that can be pushed by another fluid driven by pressure gradient. Migration of contaminants and reservoir waterflooding are typical applications where understanding the dynamics of immiscible fluid displacement helps mitigating water resources contamination and improving hydrocarbons production, respectively. Due to large viscosity ratios, flow instabilities at fluids’ interface may arise leading to the formation of fingers, i.e., uneven fronts with elongation at the outside edge of fluids interface with strong impact on the displacement efficiency. Initial studies of viscous instabilities indicated that the development of fingers mostly depends on mobility and capillary forces, however heterogeneity of the porous domain may also affect the onset of instabilities. Therefore, the main aim of this work is to numerically investigate formation and growth of viscous fingers in heterogeneous porous media. The model used here is based on a novel control volume finite element method (CVFEM) formulation with families of FE-pairs, PnDG-Pm and PnDG-PmDG, specially tailored for Darcean flows. Dynamic mesh adaptivity enables capturing fingers development whilst saving computational overheads. Numerical experiments were performed to investigate the impact of viscosity ratio and heterogeneity on Saffmann-Taylor instabilities. Numerical simulations demonstrated that the heterogeneity of the domain triggers the early-onset formation of fingers under prescribed viscosity ratio conditions. Also, effective numerical capture of growth (in particular tip-splitting) and coalescence of dendritic finger branching induced by large viscosity ratio largely depends on mesh resolution at the fluids interface.
  • A comparative analysis of capacity and non-capacity formulations for the
           simulation of unsteady flows over finite-depth erodible beds
    • Abstract: Publication date: Available online 5 June 2019Source: Advances in Water ResourcesAuthor(s): S. Martínez-Aranda, J. Murillo, P. García-Navarro Finite-depth sediment layers are common in natural water bodies. The presence of underlying bedrock strata covered by erodible bed layers is ubiquitous in rivers and estuaries. In the last years, the development of models based on the non-capacity sediment transport assumption, also called non-equilibrium assumption, has offered a new theoretical background to deal with complex non-erodible bed configurations and the associated numerical problems. Bedload non-capacity sediment transport models consider that the actual solid transport state can be different from the equilibrium state and depending on the temporal evolution of the flow. The treatment of finite-depth erodible bed layers, i.e. partially erodible beds, in bedload models based on the equilibrium approach has usually been made using numerical fixes, which correct the unphysical results obtained in some cases. Generally, the presence of a finite-depth erodible layer implies the introduction of a kind of non-equilibrium condition in the bedload transport state. Nevertheless, this common natural bed configuration has not been previously considered in the development of numerical models. In this work, a finite volume model (FVM) for bedload transport based on non-capacity approach and dealing with finite-depth erodible layers is proposed. New expressions for the actual bedload transport rate and the net exchange flux through the static-moving bed layers interface are used to develop a numerical scheme which solves the coupled shallow water and non-capacity bedload transport system of equations. The reconstruction of the intermediate states for the local Riemann problem at each intercell edge is designed to correctly model the presence of non-erodible strata, avoiding the appearance of unphysical results in the approximate solution without reducing the time step. The new coupled scheme is tested against laboratory benchmarking experiments in order to demonstrate its stability and accuracy, pointing out the properties of both equilibrium and non-equilibrium formulations.
  • Nonlinear model reduction of solute transport models
    • Abstract: Publication date: Available online 5 June 2019Source: Advances in Water ResourcesAuthor(s): Zachary P. Stanko, William W.-G. Yeh Computer simulations of groundwater flow and solute transport are often burdened by long runtimes. The simulations are necessarily complex to capture the system dynamics and finely discretized spatial and temporal domains are often needed for solution accuracy and stability. Model reduction allows for the approximation of system state by solving equations in a reduced dimensional space. Proper orthogonal decomposition (POD) is an effective way to reduce the dimensionality of systems of differential equations that are discretized by finite difference or finite element methods. If the problems are nonlinear in nature, the discrete empirical interpolation method (DEIM) has been shown to supplement POD by further reducing the dimension of nonlinear calculations. Here, the combined POD-DEIM approach is shown to work on a problem of 2-dimensional groundwater flow with solute transport exhibiting nonlinear sorption. The application is restricted to largely dispersive problems (low Peclet number). Results show areas of high concentration are effectively identified with mean errors less than 2% of the full model.
  • Analytical Pore-Network Approach (APNA): A Novel Method for Rapid
           Prediction of Capillary Pressure-Saturation Relationship in Porous Media
    • Abstract: Publication date: Available online 1 June 2019Source: Advances in Water ResourcesAuthor(s): Harris Sajjad Rabbani, Thomas Daniel Seers, Dominique Guerillot The relationship between capillary pressure and wetting fluid saturation is one of the most important functions required for the modelling of immiscible displacement within porous media. Commonly, time consuming laboratory experiments or computationally expensive pore-scale numerical simulations are performed to estimate capillary pressure− saturation relationships for a given porous media. In this research, we introduce Analytical Pore-Network Approach (APNA): a new method to forecast capillary pressure-saturation relationships in porous media. APNA is a fully coupled analytical model, that is derived using the concept of Representative Elementary Volume (REV), and underpinned by geometrical analysis of the studied pore network using pore-scale images collected by a range of imaging modalities (e.g. thin section photomicrograph, x-ray micro computed tomography, confocal microscopy, etc.). In comparison to conventional laboratory measurements and numerical simulation techniques, APNA is trivial to implement, and is capable of providing rapid estimates of capillary pressure− saturation relationships for a broad range of porous materials. We validated APNA against empirical capillary pressure− saturation data published in the literature, revealing satisfactory agreement between APNA and the experimental studies.
  • Two-site colloid transport with reversible and irreversible attachment:
           Analytical solutions
    • Abstract: Publication date: Available online 31 May 2019Source: Advances in Water ResourcesAuthor(s): Vasileios E. Katzourakis, Constantinos V. Chrysikopoulos Analytical solutions for colloid transport in water saturated, one-dimensional, homogeneous porous media, under fully developed uniform flow are presented. The colloids can be either suspended in the aqueous phase or attached reversibly and/or irreversibly onto the solid matrix. Both attachment rates are assumed linear, and any possible blocking or ripening effects are neglected. The colloids can be either of neutral density or denser than the water. For dense colloids, gravity effects are accounted for. Gravity may enhance or hinder the migration of dense colloids, depending on the flow direction. Upstream boundary conditions for both instantaneous and broad-pulse colloid injections are accounted for. The new analytical solutions were used to successfully fit available experimental data.
  • Improving flood inundation forecasts through the assimilation of in situ
           floodplain water level measurements based on alternative observation
           network configurations.
    • Abstract: Publication date: Available online 31 May 2019Source: Advances in Water ResourcesAuthor(s): Alexandra Van Wesemael, Lisa Landuyt, Hans Lievens, Niko E.C. Verhoest Reliable flood forecasting systems are the prerequisite for proper flood warning systems. Currently, satellite remote sensing (SRS) observations are widely used to improve model forecasts. Although they provide distributed information, they are sometimes unable to satisfy flood modellers’ needs due to low overpass frequencies and high measuring uncertainties. This paper assesses the potential of sparsely distributed, in situ floodplain water level sensors to provide accurate, near-real time flood information as a means to enhance flood predictions. A synthetic twin experiment evaluates the assimilation of different sensor network configurations, designed through time series clustering and Voronoi spacing. With spatio-temporal RMSEs reaching up to 1 cm, the study demonstrates great potential. Adequate sensor placement proved crucial for improved performance. In practice, observation locations should be chosen such that they are located rather close to the river, to increase the likelihood of early flooding and thus acquiring valuable information at an early stage of flooding. Furthermore, high measuring frequencies benefit the simulations, though one should be careful not to overcorrect water levels as these may result in inconsistencies. Lastly, a network size of 5 to 7 observations yields good results, while an increasing number of observations generally diminishes the importance of extra observations. Our findings could greatly contribute to future flood observing systems to either compensate for ungauged areas, or complement current SRS practices.
  • Pore Scale Study of the Influence of Particle Geometry on Soil
    • Abstract: Publication date: Available online 30 May 2019Source: Advances in Water ResourcesAuthor(s): Y.F Liu, D-S Jeng The permeability of a saturated porous medium is an important parameter in the field of water resources and geotechnical engineering. The geometric characteristics of a porous medium are key factors in the prediction of its permeability. In this paper, particles of different shapes are constructed by Cellular Automata (CA) random growth model, and particles with different surface characteristics are constructed by the spherical harmonic function. Then, porous media of different porosities, shapes, surface features, and particle size distributions are generated on the basis of the constructed particles. Three-dimensional Lattice Boltzmann Method is used for the pore-scale simulation of the seepage flow in a porous medium. The numerical results show that the effects of the particle shape and surface characteristics on the permeability are too obvious to be ignored. Using strict univariate analysis, the sensitivity of the various factors to the permeability, ordered from large to small, is as follows: porosity > particle size distribution > particle surface > particle shape. Based on numerical studies, a modified Kozeny–Carman (KC) formula is proposed by considering all the geometrical factors. All the parameters (the Wadell sphericity Sw, Cox roundness Rc, coefficient of non-uniformity Cu, the curve coefficient of curvature Cc, and effective particle size d10) in it are easily obtained in engineering practice and the accuracy of the formula is verified. Although It has been proven that the KC formula is applicable to multi-dispersed spherical particles and non-spherical particles whose surfaces are not very rough, its applicability to rough particles is limited. The modified KC formula does not have this limitation; therefore, it has a wider scope of application than the conventional KC formula.
  • Spatio-temporal analysis of compound hydro-hazard extremes across the UK.
    • Abstract: Publication date: Available online 29 May 2019Source: Advances in Water ResourcesAuthor(s): Annie Visser-Quinn, Lindsay Beevers, Lila Collet, Guiseppe Formetta, Katie Smith, Niko Wanders, Stephan Thober, Ming Pan, Rohini Kumar There exists an increasing need to understand the impact of climate change on the hydrological extremes of flood and drought, collectively referred to as ‘hydro-hazards’. At present, current methodology are limited in their scope, particularly with respect to inadequate representation of the uncertainty in the hydroclimatological modelling chain.This paper proposes spatially consistent comprehensive impact and uncertainty methodological framework for the identification of compound hydro-hazard hotspots – hotspots of change where concurrent increase in mean annual flood and drought events is projected. We apply a quasi-ergodic analysis of variance (QE-ANOVA) framework, to detail both the magnitude and the sources of uncertainty in the modelling chain for the mean projected mean change signal whilst accounting for non-stationarity. The framework is designed for application across a wide geographical range and is thus readily transferable. We illustrate the ability of the framework through application to 239 UK catchments based on hydroclimatological projections from the EDgE project (5 CMIP5-GCMs and 3 HMs, forced under RCP8.5).The results indicate that half of the projected hotspots are temporally concurrent or temporally successive within the year, exacerbating potential impacts on society. The north-east of Scotland and south-west of the UK were identified as spatio-temporally compound hotspot regions and are of particular concern. This intensification of the hydrologic dynamic (timing and seasonality of hydro-hazards) over a limited time frame represents a major challenge for future water management.Hydrological models were identified as the largest source of variability, in some instances exceeding 80% of the total variance. Critically, clear spatial variability in the sources of modelling uncertainty were also observed; highlighting the need to apply a spatially consistent methodology, such as that presented. This application raises important questions regarding the spatial variability of hydroclimatological modelling uncertainty. In terms of water management planning, such findings allow for more focussed studies with a view to improving the projections which inform the adaptation process.
  • Dispersion effects on the freshwater-seawater interface in subsea aquifers
    • Abstract: Publication date: Available online 29 May 2019Source: Advances in Water ResourcesAuthor(s): S.C. Solórzano-Rivas, A.D. Werner, D.J. Irvine Recent recognition of the widespread occurrence of freshwater beneath the ocean has renewed interest in approaches to understand and predict its extent. The most straightforward methodologies are based on the sharp-interface approximation, which neglects dispersive mechanisms. The understanding of dispersion effects on freshwater extents in coastal aquifers is based almost entirely on onshore aquifer situations. This study explores dispersion in offshore coastal aquifers, in terms of the steady-state freshwater extent, seawater circulation and freshwater discharge, through numerical experimentation. Results show that increasing dispersion causes a seaward shift in the interface toe location, as expected, whereas the interface tip shows a non-monotonic relationship with dispersion that depends on the contrast between aquifer and aquitard hydraulic conductivities. Higher dispersion leads to enhanced seawater recirculation rates and freshwater discharge, as opposed to non-monotonic relationships obtained previously for onshore aquifers. The mixing zone at the toe widens as dispersion increases, similar to onshore cases, whereas the mixing zone at the tip has a surprisingly non-monotonic relationship with dispersion. The dispersion relationships revealed in this study can be explained by counteractions between dispersion, density and advective forces, and refraction across the aquifer-aquitard interface, which in combination produce offshore aquifer behaviour that differs, in some ways, to the manner in which onshore aquifers respond to dispersive processes. Consequently, previous empirical corrections to sharp-interface methods (to account for dispersive effects) applied to onshore coastal aquifers are ineffective in their application to offshore settings.
  • Flow and bed morphology response to the introduction of wood logs for
           sediment management
    • Abstract: Publication date: Available online 29 May 2019Source: Advances in Water ResourcesAuthor(s): Judith Y. Poelman, A.J.F. (Ton) Hoitink, Timo V. de Ruijsscher Submerged vanes alter sediment transport by inducing a secondary circulation without significantly compromising the conveyance capacity of the river. Here, a laboratory study is conducted to investigate whether wood logs or trunks can be used for sediment management. The effectivity of a traditional vane field is compared to set-ups with screens of stacked logs, and large individual trunks. Results indicate that all three set-ups redistribute sediment but that the trunks are least effective in inducing a secondary circulation and cause higher turbulence and drag, leading to a stronger decrease in streamwise velocity. We conclude that a field of trunks acts as a sediment trap because of a strong reduction of the streamwise velocity, without a strong secondary flow such as dominant in the other configurations. Screens of stacked logs can be successfully implemented in rivers, as they are only slightly less effective than traditional vanes. The risk of piping underneath objects and the associated scour are points of concern.
  • Flood risk and its reduction in China
    • Abstract: Publication date: Available online 28 May 2019Source: Advances in Water ResourcesAuthor(s): ZW Kundzewicz, Buda Su, Yanjun Wang, Jun Xia, Jinlong Huang, Tong Jiang Despite massive flood protection efforts in China, undertaken since the ancient times, disastrous floods continue to plague the country. In this paper, we discuss changes in flood hazard and flood risk in China. First, we review published results (including our own works) on change detection in observed records of intense precipitation, high river flow and flood damage in China. We provide information on essential features of extreme floods in last decades - floods on large rivers, urban floods, and flash floods. Next, we review available projections for the future (including our own results), related to intense precipitation, high river flow and flood damage in China. We try to interpret the difference in flood hazard projections obtained in various publications. Since the spread of river flood hazard projections is large, projections have to be interpreted with caution, because of the impact on decisions related to climate change adaptation, flood risk reduction, and water resources management. We review flood risk reduction strategies in China, focusing on the present situation and division of responsibilities. China has embarked upon an ambitious and vigorous task to improve flood preparedness, by both structural (“hard”) defences, such as: dikes, dams and flood control reservoirs, and diversions, as well as non-structural (“soft”) measures: spatial planning and zoning; watershed management (source control), flood forecasting and warning systems; and awareness raising. The strategy of flood mitigation includes flood retention and urban water management to alleviate the burden of flash and urban flooding.
  • In-situ investigation of the impact of spreading on matrix-fracture
           interactions during three-phase flow in fractured porous media
    • Abstract: Publication date: Available online 28 May 2019Source: Advances in Water ResourcesAuthor(s): Mohammd J. Sabti, Amir H. Alizadeh, Mohammad Piri This paper presents the results of a detailed experimental study performed to examine fluid flow in a water-wet fractured sandstone rock. Using high-resolution X-ray micro computed tomography technique, we systematically investigate the pore-scale displacement mechanisms and governing interactions between the matrix and fracture during gas injection. We perform two sets of flow experiments using brine/Soltrol 170 (spreading oil)/nitrogen and brine/decalin (nonspreading oil)/nitrogen fluid systems to probe the possible beneficial role of spreading phenomena in transferring oil from the matrix to the fracture during gas injection. Gas injection after primary oil drainage was used to generate a wide range of oil saturations and pore fluid arrangements with both fluid systems. Direct visualization of the pore fluid occupancies at different oil saturations in the medium reveals the significant role that the spreading oil layers play in maintaining the hydraulic conductivity of the oil phase between the matrix and the fracture. This mainly takes place at low remaining oil saturations under the spreading condition where layer drainage, in the presence of stable and connected spreading oil layers, is the dominant displacement mechanism. In the case of high remaining oil saturations, it is observed that the oil movement is primarily governed by piston-like displacements as well as the ability of the gas phase to access the pore elements adjacent to the fracture. Under the nonspreading condition, oil cannot maintain its connectivity due to the absence of the spreading layers, leading to higher residual oil saturations in the matrix and lower ultimate oil recovery.
  • Characterising Uncertainty in Precipitation Downscaling using a Bayesian
    • Abstract: Publication date: Available online 25 May 2019Source: Advances in Water ResourcesAuthor(s): Ahmad Hasan Nury, Ashish Sharma, Lucy Marshall, Raj Mehrotra Statistical downscaling of GCM simulations is widely used for examining future changes in precipitation at different spatial and temporal scales. However, the downscaling process is affected by uncertainty associated with the downscaling model, its parameters, and also the use of different reanalysis products for model calibration. This study develops a Bayesian approach to calibrating a statistical downscaling model. The study investigates the impact of using two different reanalysis products, the National Centre for Environmental Prediction/National Centre for Atmospheric Research Reanalysis 2 (NCEP2) and the European Centre for Medium-Range Forecasts Interim Reanalysis (ERAI), in precipitation downscaling over the Tibetan plateau, a region with sparse ground precipitation coverage. The selected reanalysis products are used for modelling precipitation at selected locations with long, high quality records and diverse geographic characteristics. An assessment of the downscaled precipitation results using atmospheric variables from the ACCESS 1.3 GCM to drive the downscaling model calibrated using a reanalysis dataset is also performed and the impact of calibration uncertainty quantified. The outcomes of this study reveal that the choice of the data length used and the type of Reanalysis product adopted have a significant effect in downscaled precipitation characteristics and their uncertainties, such as the wetness fraction and average annual precipitations over the study locations. These findings point to a common problem in statistical downscaling applications and one that has not been recognised until now. The results show that downscaling model considering ERAI reproduce observed precipitation attributes to a better extent than NCEP2.
  • Permeability Sensitivity Functions and Rapid Simulation of Multi-Point
           Pressure Measurements Using Perturbation Theory
    • Abstract: Publication date: Available online 24 May 2019Source: Advances in Water ResourcesAuthor(s): J.D. Escobar Gómez, C. Torres-Verdín We introduce a perturbation method for the forward modeling of transient diffusion phenomena in aquifers with pressure measurements acquired at arbitrary observation points. Our numerical approach requires only two simulations to compute the Permeability Sensitivity Function (PSF) at an observation point under multi-source and multi-rate conditions; one simulation captures the pressure solution due to the flow history of the sources, while the second simulation is required to extract the Green's function of the groundwater system. The PSF is calculated on the spatial-temporal domain by convolving the gradients of the pressure solution and of the Green's function. The first-order term in the perturbation expansion is obtained by weighting the spatial variations of permeability with a flow-history-dependent PSF.Our work confirms the flexibility and reliability of the method after successful validation with forward numerical simulations in cylindrical and Cartesian coordinates. Multidimensional synthetic studies including multi-well and formation testing conditions, were examined for diverse anisotropy-dominated fluid-flow regimes. Against perturbations of more than one order of magnitude in background permeability, results show that first-order approximations can be computed in tens of CPU seconds with relative errors in pressure of < 7%. Results indicate that sensitivity functions enable improved qualitative understanding of permeability-pressure correlations and local Darcy flow dynamics.
  • Iterative Multiscale Gradient Computation for Heterogeneous Subsurface
    • Abstract: Publication date: Available online 23 May 2019Source: Advances in Water ResourcesAuthor(s): Rafael J. de Moraes, Wessel de Zeeuw, José Roberto P. Rodrigues, Hadi Hajibeygi, Jan Dirk Jansen We introduce a semi-analytical iterative multiscale derivative computation methodology that allows for error control and reduction to any desired accuracy, up to fine-scale precision. The model responses are computed by the multiscale forward simulation of flow in heterogeneous porous media. The derivative computation method is based on the augmentation of the model equation and state vectors with the smoothing stage defined by the iterative multiscale method. In the formulation, we avoid additional complexity involved in computing partial derivatives associated to the smoothing step. We account for it as an approximate derivative computation stage. The numerical experiments illustrate how the newly introduced derivative method computes misfit objective function gradients that converge to fine-scale one as the iterative multiscale residual converges. The robustness of the methodology is investigated for test cases with high contrast permeability fields. The iterative multiscale gradient method casts a promising approach, with minimal accuracy-efficiency tradeoff, for large-scale heterogeneous porous media optimization problems.
  • Impact of climate change on European winter and summer flood losses
    • Abstract: Publication date: Available online 21 May 2019Source: Advances in Water ResourcesAuthor(s): Maximiliano Sassi, Ludovico Nicotina, Pardeep Pall, Dáithí Stone, Arno Hilberts, Michael Wehner, Stephen Jewson Climate change is expected to alter European floods and associated economic losses in various ways. Here we investigate the impact of precipitation change on European average winter and summer financial losses due to flooding under a 1.5°C warming scenario (reflecting a projected climate in the year 2115 according to RCP2.6) and for a counterfactual current-climate scenario where the climate has evolved without anthropogenic influence (reflecting a climate corresponding to pre-industrial conditions). Climate scenarios were generated with the Community Atmospheric Model (CAM) version 5. For each scenario, we derive a set of weights that when applied to the current climate's precipitation results in a climatology that approximates that of the scenario. We apply the weights to annual losses from a well-calibrated (to the current climate) flood loss model that spans 50,000 years and re-compute the average annual loss to assess the impact of precipitation changes induced by anthropogenic climate change. The method relies on a large stochastic set of physically based flood model simulations and allows quick assessment of potential loss changes due to change in precipitation based on two statistics, namely total precipitation, and total precipitation of very wet days (defined here as the total precipitation of days above the 95th percentile of daily precipitation). We compute the statistics with the raw CAM precipitation and bias-corrected precipitation. Our results show that for both raw and bias-corrected statistics i) average flood loss in Europe generally tend to increase in winter and decrease in summer for the future scenario, and consistent with that change we also show that ii) average flood losses have increased (decreased) for winter (summer) from pre-industrial conditions to the current day. The magnitude of the change varies among scenarios and statistics chosen.
  • The solution of the Riemann problem in rectangular channels with
           constrictions and obstructions
    • Abstract: Publication date: Available online 21 May 2019Source: Advances in Water ResourcesAuthor(s): Veronica Pepe, Luigi Cimorelli, Giovanni Pugliano, Renata Della Morte, Domenico Pianese, Luca Cozzolino Usually, the rapid geometric transitions that are of negligible length with respect to the channel are treated in one-dimensional Saint Venant models as internal boundary conditions, assuming that an instantaneous equilibrium is attained between the flow characteristics through the structure and the flow characteristics in the channel. In the present paper, a different point of view is assumed by considering rapid transients at channel constrictions and obstructions that are caused by the lack of instantaneous equilibrium between the flow conditions immediately upstream and downstream of the structure. These transients are modelled as a Riemann problem, assuming that the flow through the geometric transition is described by a stationary weak solution of the Saint Venant equations without friction. For this case, it is demonstrated that the solution of the Riemann problem exists and it is unique for a wide class of initial flow conditions, including supercritical flows. The solutions of the Riemann problem supplied by the one-dimensional mathematical model compare well with the results of a two-dimensional Shallow Water Equations numerical model when the head loss through the structure is negligible. The inspection of the exact solutions structure shows that the flow conditions immediately to the left and to the right of the geometric discontinuity may be very different from the initial conditions, and this contributes to explain the numerical issues that are reported in the literature for the rapid transients at internal boundary conditions in finite difference models. The solution of the Riemann problem has been coded, and the corresponding exact fluxes have been used as numerical fluxes in a one-dimensional Finite Volume scheme for the solution of the Shallow water Equations. The results demonstrate that spurious oscillations and instability phenomena are completely eliminated, ensuring the robustness of the approach. In the case that the energy loss is not negligible, the exact solutions capture the essential features of the two-dimensional model numerical results, ensuring that the mathematical procedure is generalizable to realistic conditions. This generalization is presented in the final part of the paper.
  • Floating treatment islands in series along a channel: the impact of island
           spacing on the velocity field and estimated mass removal.
    • Abstract: Publication date: Available online 18 May 2019Source: Advances in Water ResourcesAuthor(s): Chao Liu, Yuqi Shan, Jiarui Lei, Heidi Nepf Floating treatment islands (FTIs) consist of emergent vegetation grown on floating structures. The submerged roots beneath the island and the biofilm they support filter nutrients and particulates from water passing through the roots. FTIs are often deployed in series within a channel, but an optimum spacing between FTIs has not yet been determined. The goal of the present study is to identify an optimum spacing for maximum mass removal per channel length. A series of scaled FTI models were deployed in a water channel with the spacing between FTIs ranging from 0.5 to 11 times the length of an individual root zone. A Nortek Vectrino was used to measure the velocity field to determine the flow rate into and residence time within each root zone. The measured flow distribution was used within a control volume analysis to estimate the mass removed per channel length, assuming that removal within the root zone followed a first-order reaction. As the spacing between the FTIs decreased, the flow entering each FTI root zone also decreased, which decreased the mass removal of each individual FTI. However, as the spacing between FTIs was decreased, the number of FTIs per channel length increased, which tended to increase the mass removal of the system of FTI in series. These competing trends produced a maximum mass removal for FTIs spaced between one and three times the root zone length. The maximum spacing was weakly dependent on the assumed first-order reaction rate. The present study can help designers choose an optimal spacing for FTIs in series to achieve the maximum mass removal per river length.
  • From patch to channel scale: the evolution of emergent vegetation in a
    • Abstract: Publication date: Available online 18 May 2019Source: Advances in Water ResourcesAuthor(s): Taís N. Yamasaki, Paulo H.S. de Lima, Diego F. Silva, Cristiane G de A. Preza, Johannes G. Janzen, Heidi M. Nepf Computational fluid dynamics was used to study the evolution of small patches of vegetation into a vegetated landscape in a channel. The growth of new vegetation occurred in regions where the flow velocity was reduced below a threshold value defined as a fraction of the channel-average velocity (U0). Two threshold values, or limiting velocity values (LV), were used: LV = 0.5 and 0.7. Two initial blockage factors (percentage vegetation coverage of the channel) were considered, 3% and 0.3%, chosen to represent cases with and without, respectively, hydrodynamic interaction between the initial patches. The simulation illustrated both positive feedbacks between flow and vegetation, which enhanced vegetation expansion, and negative feedbacks, which led to patch erosion and limited patch growth. The most rapid expansion of the vegetated area occurred during the initial simulation steps, when the flow blockage due to vegetation was small. A higher velocity threshold (higher LV) produced more rapid initial growth and a higher final coverage of vegetation. The patches evolved to one or a few elongated islands extending along the channel.
  • An Extension of Darcy’s Law Incorporating Dynamic Length Scales
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Water ResourcesAuthor(s): Yuhang Wang, Saman A. Aryana, Myron B. Allen We propose a physics-based, macroscale formulation of multiphase porous-media flows that both honors the validity of Darcy’s law in steady or near-steady flows and accommodates the effects of heterogeneities and nonlinearities in unsteady flows. The new formulation recognizes that parameters characterizing the system operate at different length-scales. In particular, the use of Darcy’s law, predicated on the assumption of near-steady flows, requires dynamic length scales, owing to the possibility of rapid fluctuations in rock properties and fluid saturations attributable to heterogeneity and nonlinearity. We accommodate these dynamic length-scales through dynamic spatial averaging. The length and position of the averaging window are characterized by the length of the mixing zone and the direction of propagation of information in the transport process. We validate the proposed formulation by comparing highly accurate, two-dimensional numerical solutions against core-scale displacement experiments. The proposed paradigm is consistent with the classical multiphase Darcy formulation, in the sense that the latter also represents the results of an averaging approach.
  • Green-blue water accounting in a soil water balance
    • Abstract: Publication date: Available online 17 May 2019Source: Advances in Water ResourcesAuthor(s): Arjen Y. Hoekstra It has become common practice to speak about ‘green’ versus ‘blue’ water consumption, in order to distinguish between consumption of rainwater versus groundwater or surface water. The two sources of water differ in terms of possibilities for storage and use. Whereas industrial, municipal and livestock water supply primarily depend on blue water, crop cultivation relies on both green and blue water. Discriminating between green and blue water consumption in a crop field is not straightforward: consumption refers to evapotranspiration (ET) and water contained in the harvested crop, which both appear in undifferentiated form. One cannot see which part of ET or the water in a plant originates from rainwater and which part from irrigation water. In this paper I propose a generic and physically based method to differentiate green and blue evaporation (E) and green and blue transpiration (T) by daily accounting of the fractions green and blue water in each soil and vegetation layer. The green and blue fractions of all water fluxes leaving a soil or vegetation layer in a day depend on the average green and blue water fractions in that soil or vegetation layer during that day. This method allows for an accurate assessment of irrigation efficiency (the ratio of blue water transpiration to the irrigation water applied), and for a precise estimation of green and blue water footprints of crop production (the ratio of either green ET or blue ET to the crop yield).
  • A general Beerkan Estimation of Soil Transfer parameters method predicting
           hydraulic parameters of any unimodal water retention and hydraulic
           conductivity curves: application to the Kosugi soil hydraulic model
           without using particle size distribution data
    • Abstract: Publication date: Available online 16 May 2019Source: Advances in Water ResourcesAuthor(s): J. Fernández-Gálvez, J.A.P. Pollacco, L. Lassabatere, R. Angulo-Jaramillo, S. Carrick Soil hydraulic characterization is crucial to describe the retention and transport of water in soil, but current methodologies limit its spatial applicability. This paper presents a cost-effective general Beerkan Estimation of Soil Transfer parameters (BEST) methodology using single ring infiltration experiments to derive soil hydraulic parameters for any unimodal water retention and hydraulic conductivity functions. The proposed method relies on the BEST approach. The novelty lies in the use of Kosugi hydraulic parameters without need for textural information. In addition, the method uses a quasi-exact formulation that is valid for all times, which avoids the use of approximate expansions and related inaccuracy. The new BEST methods were tested against numerically generated data for several contrasting synthetic soils, and the results show that these methods provide consistent hydraulic functions close to the target functions. The new BEST method is accurate and can use any water retention and hydraulic conductivity functions.
  • Evaluation of Water Permeability of Rough Fractures Based on a Self-affine
           Fractal Model and Optimized Segmentation Algorithm
    • Abstract: Publication date: Available online 16 May 2019Source: Advances in Water ResourcesAuthor(s): Yang Ju, Jiabin Dong, Feng Gao, Jianguo Wang The water permeability of natural fractures is highly related to their morphological characteristics. For fractures with irregular profiles and variable apertures, it is challenging to define an appropriate aperture to apply the traditional cubic law for evaluating permeability. In this study, we propose a novel approach that integrates the standard deviation and the Hurst exponent of a self-affine fracture profile to characterise the effects of fracture morphology on permeability using Cuckoo search algorithms. A modified local cubic law was derived to evaluate permeability, considering the roughness and Hurst exponent of fractures. The required number of segments for a fracture was obtained by comparing simulation results using Lattice Boltzmann methods. The proposed permeability model and segment strategy were validated by experiments on rough fractures. The results show that the number of segments required for the model can be directly derived from the dimensionless aperture (i.e., mechanical aperture/length of fracture media).
  • Combining a land surface model with groundwater model calibration to
           assess the impacts of groundwater pumping in a mountainous desert basin
    • Abstract: Publication date: Available online 16 May 2019Source: Advances in Water ResourcesAuthor(s): Kuai Fang, Xinye Ji, Chaopeng Shen, Noel Ludwig, Peter Godfrey, Tasnuva Mahjabin, Christine Doughty The quantification of recharge and trans-valley underflow is needed in arid regions to estimate the impacts of new water withdrawals on the water table. However, for mountainous desert areas, such estimates are highly challenging, due to data scarcity, heterogeneous soils, and long residence times. Conventional assessment employs isolated groundwater models configured with simplified uniform estimates of recharge. Here, we employed a data-constrained surface-subsurface process model to provide an ensemble of spatially distributed recharge and underflow estimates using perturbed parameters. Then, the Model-Independent Parameter Estimation and Uncertainty Quantification (PEST) package was used to calibrate the aquifer hydraulic conductivity field in MODFLOW for this ensemble and reject implausible recharge values. This novel dual-model approach, broadly applicable to mountainous arid regions, was designed to maximally exploit available data sources. It can assimilate groundwater head observations, reject unrealistic parameters, and narrow the range of estimated drawdowns due to pumping. We applied this approach to the Chuckwalla basin in California, USA to determine natural recharge. Simulated recharge concentrates along alluvial fans at the mountain fronts and ephemeral washes where run-off water infiltrates. If an evenly distributed recharge was employed as in conventional studies, it would result in regional biases in estimated drawdown and larger uncertainty bounds. We also note that the speed of groundwater recovery does not guarantee sustainability: heavy pumping induces large hydraulic gradients that initially recover quickly when pumping is halted, but the system may not ultimately recover to pre-pumping levels.
  • Modeling subgrid-scale topographic effects on shallow marsh hydrodynamics
           and salinity transport
    • Abstract: Publication date: Available online 10 May 2019Source: Advances in Water ResourcesAuthor(s): Zhi Li, Ben R. Hodges A 2D depth-integrated subgrid hydrodynamic model (FrehdC) is designed to simulate effects of subgrid-scale topography on flow and scalar transport in shallow coastal marshes using computationally-efficient grid cells that are coarser than many of the channelized paths through the marsh. The subgrid-scale topography is parametrized into four depth-dependent variables (subgrid cell volume and three subgrid face areas) that characterize the high-resolution features of coarse grid cells. These variables are pre-stored in a table and embedded into the governing equations as model inputs to scale cell storage, mass and momentum fluxes across cell faces. A block-checking procedure is designed to automatically preserve high-resolution surface connectivity during grid-coarsening. By testing on both synthetic domain and real marshes, this new model is able to approximate fine-grid simulation results of surface elevation, inundation area, flow rate and salinity with less computational cost.
  • Unconditional and Conditional Solute Concentrations as Sampled in Natural
    • Abstract: Publication date: Available online 10 May 2019Source: Advances in Water ResourcesAuthor(s): Shayan Maleki, Virgilio Fiorotto The aim of this paper is to analyze the statistical properties of non-reactive solute concentrations in natural aquifers, taking into account the hydraulic conductivity heterogeneity. Quantifying the uncertainty in the evaluation of solute concentrations in aquifers is an important issue for human health and in ecological risk analysis. In particular, the concentration Cumulative Distribution Function (CDF) is a key element, as it informs the decision makers of the probability that the concentration at an environmental target is below a maximum contaminant level. The analysis presented in this paper is performed in a Lagrangian framework. According to the “reverse formulation”, the origin of the particle being sampled is sought instead of considering the destination of the injected particles. Based on this formulation, a closed form for the unconditioned concentration CDF is derived. The same procedure is applied to obtain a closed form for the concentration conditioned by measurements at sampling points in an aquifer.
  • Using a simple post-processor to predict residual uncertainty for multiple
           hydrological model outputs
    • Abstract: Publication date: Available online 8 May 2019Source: Advances in Water ResourcesAuthor(s): L.B. Ehlers, O. Wani, J. Koch, T.O. Sonnenborg, J.C. Refsgaard Regardless of the complexity of the hydrological model employed, uncertainty assessment (UA) is predominantly performed for the aggregated catchment response discharge. For coupled integrated models that simulate various hydrological states and fluxes on a grid cell basis, this represents a severe shortcoming. We test a simple data-driven technique (k-NN resampling) to evaluate its ability to provide reliable residual uncertainty estimates for the multi-variable (discharge, hydraulic head, soil moisture and actual evapotranspiration), deterministic output of two coupled groundwater-surface water models with different complexities. Being a nonparametric method, no explicit prior assumptions about the error distribution of different hydrological variables are required. When conditioning the algorithm, we propose to limit the number of error lags to be included based on inspection of the partial autocorrelation function (PACF). Our results confirm previous findings regarding reliability and robustness of the k-NN technique for discharge simulations and conclude that k-NN resampling also provides reliable and robust results for other variables like hydraulic head, soil moisture and actual evapotranspiration, even for underlying hydrological models with varying levels of performance. The 90 % prediction intervals (PI) capture the observations in the testing period satisfactorily for all hydrological variables (92.6–97.3 %), while Alpha indices (0.84–0.95) indicate very reliable PIs for all error quantiles. Differences in error structure between hydrological variables are successfully inferred from historical data and reflected in the results. We conclude that k-NN resampling represents a potent, cost-efficient UA technique for applications in operational hydrology, facilitating a near-simultaneous, easy uncertainty assessment for various outputs of computationally heavy hydrological models.
  • (Multi)wavelets increase both accuracy and efficiency of standard
           Godunov-type hydrodynamic models
    • Abstract: Publication date: Available online 30 April 2019Source: Advances in Water ResourcesAuthor(s): Georges Kesserwani, James Shaw, Mohammad K Sharifian, Domenico Bau, Christopher J Keylock, Paul D Bates, Jennifer K Ryan This paper presents a scaled reformulation of a robust second-order Discontinuous Galerkin (DG2) solver for the Shallow Water Equations (SWE), with guiding principles on how it can be naturally extended to fit into the multiresolution analysis of multiwavelets (MW). Multiresolution analysis applied to the flow and topography data enables the creation of an adaptive MWDG2 solution on a non-uniform grid. The multiresolution analysis also permits control of the adaptive model error by a single user-prescribed parameter. This results in an adaptive MWDG2 solver that can fully exploit the local (de)compression of piecewise-linear modelled data, and from which a first-order finite volume version (FV1) is directly obtainable based on the Haar wavelet (HFV1) for local (de)compression of piecewise-constant modelled data. The behaviour of the adaptive HFV1 and MWDG2 solvers is systematically studied on a number of well-known hydraulic tests that cover all elementary aspects relevant to accurate, efficient and robust modelling. The adaptive solvers are run starting from a baseline mesh with a single element, and their accuracy and efficiency are measured referring to standard FV1 and DG2 simulations on the uniform grid involving the finest resolution accessible by the adaptive solvers. Our findings reveal that the MWDG2 solver can achieve the same accuracy as the DG2 solver but with a greater efficiency than the FV1 solver due to the smoothness of its piecewise-linear basis, which enables more aggressive coarsening than with the piecewise-constant basis in the HFV1 solver. This suggests a great potential for the MWDG2 solver to efficiently handle the depth and breadth in resolution variability, while also being a multiresolution mesh generator. Accompanying model software and simulation data are openly available online.
  • Derivation of canonical total-sequences triggering landslides and
           floodings in complex terrain
    • Abstract: Publication date: Available online 26 April 2019Source: Advances in Water ResourcesAuthor(s): Katharina Enigl, Christoph Matulla, Matthias Schlögl, Franz Schmid Floodings and landslides are amongst the most devastating damage-processes worldwide. Associated risk levels are particularly high in topographically complex terrain. Along with the increase in climate-change induced extreme-events, research devoted to the identification of so-called Climate Indices (CIs) describing weather phenomena triggering hazard-occurrences and intensities gain rising emphasis.In this study we accomplish the first-time unification of the three most comprehensive cadastres on weather-induced hazard-processes, compiled and maintained by federal authorities. The therefrom resulting ‘event space’ stretches seven decades from 1950 onwards and contains more than 20.000 hazard occurrences, classified into different process-categories. Event data are analyzed together with a high-quality, daily-based dataset providing temperatures and precipitation totals on a 1 km grid across the Austrian part of the European Alps.On the resulting unprecedented extent of extreme-weather triggered hazard-processes and gridded weather observations we are able to examine the hypothesis that daily sequences of precipitation-totals preceding damage-events allow for detecting temporal weather sequences uniquely allocatable to various hazard-categories in three orographically distinct regions in the European Alps. We pursue this research aim by analyzing for each hazard-category its quadratic form representing the physics contained in the observations. Resulting eigen-directions, invariant under its inherent second order tensor, are the sought-for total-sequences (CIs) and hence reject the alternative hypothesis. Therefore, precipitation total-sequences can be uniquely assigned to hazard categories within each region.It is important to note that findings based on this novel, objective approach do not contradict, but rather add to attained research achievements by introducing this new perspective on the subject.Obtained CIs have substantial potential in research and applications. In civil defense, safeguarding critical infrastructure, early warning systems and the development of sustainable protection strategies, findings are in implementation by responsible decision-makers and in intense discussion with the European Freight and Logistics Leaders’ Forum.
  • Pore Occupancy, Relative Permeability and Flow Intermittency Measurements
           Using X-Ray Micro-tomography in a Complex Carbonate
    • Abstract: Publication date: Available online 10 April 2019Source: Advances in Water ResourcesAuthor(s): Ying Gao, Ali Q. Raeini, Martin J. Blunt, Branko Bijeljic We imaged the steady-state flow of brine and decane (oil) at different fractional flows during dual injection in a micro-porous limestone, Estaillades, using X-ray micro-tomography. We applied differential imaging to (a) distinguish micro-porous regions from macro-pores, and (b) determine fluid pore occupancy in both regions, and relative permeability at a capillary number, Ca = 7.3 × 10−6. The sample porosity was approximately 28%, with 7% in macro-pores and 21% in pores that could not be directly resolved (micro-porosity). Fluid occupancy in micro-porosity was classified into three sub-phases: micro-pore space with oil, micro-pore space with brine, and micro-pores partially filled with oil and brine. Our method indicated an initially higher oil recovery from micro-porosity, consistent with waterflooding in a water-wet rock. The fractional flow and relative permeabilities of the two fluids were obtained from measurements of the pressure differential across the sample and the saturation calculated from the images. The brine saturation and relative permeabilities are impacted by the presence of water-wet micro-porosity which provides additional connectivity to the phases. Furthermore, we find that in addition to brine and decane, a fraction of the macroscopic pore space contains an intermittent phase, which is occupied either by brine or decane during the hour-long scan time. Pore and throat occupancy of oil, brine and intermittent phase were obtained from images at different fractional flows using the generalized pore network extracted from the image of macro-pores. The intermittent phase, where the occupancy fluctuated between oil-filled and brine-filled, was predominantly located in the small and intermediate size pores and throats. Overall, we establish a new experimental methodology to (i) quantify initial and recovered oil in micro-pores, (ii) characterise intermittent flow, and (iii) measure steady-state relative permeability in carbonates, which is shown to be greatly influenced by micro-porosity.
  • Corrigendum to “A new upscaling method for fractured porous media”
           [Advances in Water Resources 80 (2015): 60-68.]
    • Abstract: Publication date: Available online 11 January 2019Source: Advances in Water ResourcesAuthor(s): Tao Chen, Christoph Clauser, Gabriele Marquart, Karen Willbrand, Darius Mottaghy
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