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Publisher: Elsevier   (Total: 3163 journals)

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Showing 1 - 200 of 3163 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 9)
AASRI Procedia     Open Access   (Followers: 14)
Academic Pediatrics     Hybrid Journal   (Followers: 30, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 22, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 88, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 35, 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: 394, 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: 2)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.18, CiteScore: 1)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.128, CiteScore: 0)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 244, 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: 10, 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: 27, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access  
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: 6, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 6)
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: 16, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 8, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 9, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Cement Based Materials     Full-text available via subscription   (Followers: 3, SJR: 0.732, CiteScore: 3)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 134, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 12, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 28, 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: 10, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 14, 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: 29, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 7, 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: 3)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 27, 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: 28, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19, 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: 11)
Advances in Digestive Medicine     Open Access   (Followers: 8)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 23)
Advances in Ecological Research     Full-text available via subscription   (Followers: 42, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 27, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 43, 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: 53, 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: 15, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 8, 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: 21, 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: 22)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 8, 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: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 14, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 11, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
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: 21)
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: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 16, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 6, 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: 24, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 10)
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: 8, 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: 8)
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: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 59)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (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: 5)
Advances in Space Research     Full-text available via subscription   (Followers: 385, 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: 10, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 29, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 46, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 335, 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: 10, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 436, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 43, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 1)
Agriculture and Natural Resources     Open Access   (Followers: 2)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 56, 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: 11, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 9)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 10, 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: 9, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 50, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 50, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 51, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 44, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 10)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 32, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 26, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 34, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 43)
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: 203, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 62, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 6, 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: 27, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 27, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 37, 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: 6)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 63, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 15, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription  
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: 39, SJR: 1.512, CiteScore: 5)
Analytical Biochemistry     Hybrid Journal   (Followers: 174, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 10, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 23, 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)

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Journal Cover
Advances in Water Resources
Journal Prestige (SJR): 1.551
Citation Impact (citeScore): 3
Number of Followers: 46  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0309-1708
Published by Elsevier Homepage  [3163 journals]
  • Water residence time controls the feedback between seagrass, sediment and
           light: Implications for restoration
    • Authors: Matthew P. Adams; Marco Ghisalberti; Ryan J. Lowe; David P. Callaghan; Mark E. Baird; Eduardo Infantes; Katherine R. O’Brien
      Pages: 14 - 26
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Matthew P. Adams, Marco Ghisalberti, Ryan J. Lowe, David P. Callaghan, Mark E. Baird, Eduardo Infantes, Katherine R. O’Brien
      Feedbacks between seagrass and the local environmental conditions may hinder attempts to restore seagrass by inducing alternative stable states. A one-dimensional physical-biological model was used to identify the conditions under which a feedback between seagrass, sediment and light can yield alternative stable states of seagrass presence and absence (bistability). Based on our model results, a prediction of whether a given seagrass meadow is large enough to promote seagrass growth can now be made. If the water residence time within the spatial area of the meadow is similar to or greater than the sediment settling time, which is calculated from the ratio of water depth to sediment vertical settling velocity, the meadow is large enough for the feedback to potentially reduce the local suspended sediment concentration. This has important implications for seagrass restoration: for a proposed restoration plot, if the water residence time is similar to or greater than the sediment settling time, the scale of restoration is large enough for the feedback between seagrass, sediment and light to locally improve water clarity. More generally, this calculation can be used to identify areas where this feedback is likely to generate bistability, and to estimate the minimum suitable meadow size in such locations.
      Graphical abstract image

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.04.004
      Issue No: Vol. 117 (2018)
       
  • Metastatistical Extreme Value analysis of hourly rainfall from short
           records: Estimation of high quantiles and impact of measurement errors
    • Authors: Francesco Marra; Efthymios I. Nikolopoulos; Emmanouil N. Anagnostou; Efrat Morin
      Pages: 27 - 39
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Francesco Marra, Efthymios I. Nikolopoulos, Emmanouil N. Anagnostou, Efrat Morin
      This study expands the Metastatistical Extreme Value (MEV) framework to sub-daily rainfall frequency analysis and compares it to extreme value theory methods in presence of short records and measurement errors. Ordinary events are identified based on the temporal autocorrelation of hourly data and modeled with a Weibull distribution. MEV is compared to extreme value theory methods in the estimation of long return period quantiles from actual data (160 rain gauges with at least 60-year record in the contiguous United States) and on synthetic data perturbed with measurement errors typical of remote sensing rainfall estimation. MEV tends to underestimate the 100-year return period quantiles of hourly rainfall when 5–20 years of actual data are used, but presents diminished uncertainty. When a good model of the ordinary events and adequate number of events per year are available, MEV is able to provide information on the 100-year return period quantiles from 10–20, or even 5 years of data with significantly reduced uncertainty (<30% uncertainty for 5-year records). MEV estimates of 100-year return period quantiles from short records are much less sensitive than extreme value theory methods to additive/multiplicative errors, presence of cap values in the estimates, and missing of extreme values. Results from this study strongly support the use of MEV for rainfall frequency analyses based on remotely sensed datasets.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.001
      Issue No: Vol. 117 (2018)
       
  • Mathematical study of linear morphodynamic acceleration and derivation of
           the MASSPEED approach
    • Authors: F. Carraro; D. Vanzo; V. Caleffi; A. Valiani; A. Siviglia
      Pages: 40 - 52
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): F. Carraro, D. Vanzo, V. Caleffi, A. Valiani, A. Siviglia
      Morphological accelerators, such as the MORFAC (MORphological acceleration FACtor) approach (Roelvink, 2006), are widely adopted techniques for the acceleration of the bed evolution, which reduce the computational cost of morphodynamic numerical simulations. In this work we apply an acceleration to the one-dimensional morphodynamic problem described by the de Saint Venant–Exner model by multiplying all the spatial derivatives related to the mass or momentum flux by an acceleration factor  ≥ 1 which may be different for each equation. The goal is to identify the best combination of the accelerating factors for which (i) the bed responds linearly to hydrodynamic changes; (ii) a decrease of the computational cost is obtained. The sought combination is obtained by studying the behavior of an approximate solution of the three eigenvalues associated with the flux matrix of the accelerated system. This approach allows to derive a new linear morphodynamic acceleration technique, the MASSPEED (MASs equations SPEEDup) approach, and the a priori determination of the highest possible acceleration for a given simulation. In this new approach both mass conservation equations (water and sediment) are accelerated by the same factor, differently from the MORFAC approach where only the sediment mass equation is modified. The analysis shows that the MASSPEED gives a larger validity range for linear acceleration and requires smaller computational costs than that of the MORFAC approach. The MASSPEED approach is then implemented using an adaptive approach that applies the maximum linear acceleration similarly to the implementation of the Courant–-Friedrichs–-Lewy stability condition. Finally, numerical simulations have been performed in order to assess accuracy and efficiency of the new approach. Results obtained in the long-term propagation of a sediment hump demonstrate the advantages of the new approach. The validation of the method is performed under steady or quasi-steady flow conditions, whereas further investigation is needed to extend morphological accelerators to fully unsteady flows.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.002
      Issue No: Vol. 117 (2018)
       
  • Bayesian selection of hydro-morphodynamic models under computational time
           constraints
    • Authors: Farid Mohammadi; Rebekka Kopmann; Anneli Guthke; Sergey Oladyshkin; Wolfgang Nowak
      Pages: 53 - 64
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Farid Mohammadi, Rebekka Kopmann, Anneli Guthke, Sergey Oladyshkin, Wolfgang Nowak
      A variety of empirical formulas to predict river bed evolution with hydro-morphodynamic river models exists. Modelers lack objective guidance of how to select the most appropriate one for a specific application. Such guidance can be provided by Bayesian model selection (BMS). Its applicability is however limited by high computational costs. To transfer it to computationally expensive river modeling tasks, we propose to combine BMS with model reduction based on arbitrary Polynomial Chaos Expansion. To account for approximation errors in the reduced models, we introduce a novel correction factor that yields a reliable model ranking even under strong computational time constraints. We demonstrate our proposed approach on a case study for a 10-km stretch of the lower Rhine river. The correction factor may shield us from misleading model ranking results. In our case, the correction factor was shown to increase the confidence in model selection.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.007
      Issue No: Vol. 117 (2018)
       
  • Contaminant dilution measure for the solute transport in an estuary
    • Authors: Roko Andričević; Morena Galešić
      Pages: 65 - 74
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Roko Andričević, Morena Galešić
      The pollution pressures on coastal waters predominantly come from the river freshwater transport and loadings of contaminants into the estuary. This study presents the probabilistic model of the near field solute transport in an estuary based on the spatially integrated concentration statistics. A methodology is presented for quantifying the degree of dilution within the surface layer in terms of expected mass and volume fraction functions as a simple alternative to the point concentration probability density function. The theoretical prediction is experimentally validated using the salinity dilution as an inverse process in the field case of river Žrnovnica near the city of Split. A novel dilution measure is presented as combination of expected mass and volume fraction indicating the area of an estuary where dilution process will attenuate the concentration of a passive contaminant below any selected environmental limits. Introduced dilution measure directly corresponds to different catchment loadings through the river as a hydrological pathway of mass transport and can be used for assessing water quality status for transitional water bodies and to guide future efforts for monitoring potential eutrophication hot-spots in the coastal area.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.005
      Issue No: Vol. 117 (2018)
       
  • Water level variability of the Mirim - São Gonçalo system, a large,
           subtropical, semi-enclosed coastal complex
    • Authors: Juliana Costi; Wiliam Correa Marques; Eduardo de Paula Kirinus; Raquel de Freitas Duarte; Jorge Arigony-Neto
      Pages: 75 - 86
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Juliana Costi, Wiliam Correa Marques, Eduardo de Paula Kirinus, Raquel de Freitas Duarte, Jorge Arigony-Neto
      Coastal lagoons, channels, and wetlands are sensitive ecosystems with high productivity and biodiversity. These systems often provide society with the valuable freshwater resources and many ecosystem services. In the subtropics, the hydrological systems inherit the typically high climatic and weather variability characteristics of these zones. Therefore, knowing the natural variability of these characteristics is crucial for the sustainable use of the water resources of these systems. In the present paper, we investigated the hydrodynamics of the Mirim-São Gonçalo system, which comprises a large, shallow coastal lake, a 78 km-long channel and their adjacent floodplains and wetlands, with a focus on water level oscillations. We used a combination of numerical simulations, gauge station data and Synthetic Aperture RADAR imaging to evaluate the influence of the incident winds and the discharges of the main tributaries on the system’s water levels and the establishment of barotropic gradients. We analyzed the water level variability of the Mirim lagoon and the São Gonçalo Channel and their overflows to the adjacent floodplains. The simulations are five years long and cover the period starting in January 2000 to December 2004. The analysis indicates that the discharge of the tributaries mainly governs the system’s temporal patterns. Wind action has two distinct influences on the systems. First, the wind dams the water at the southern portion of the Mirim Lagoon, which creates a persistent barotropic gradient in the surface. This gradient is often destroyed and dislocated northwards in a rotational fashion when the wind blows from the southern quadrant. Second, the wind perturbs the temporal variability patterns, resulting in high-frequency oscillations of the water level temporal signal. Flooding is frequent in the lands adjacent to the lagoon and the channel and results from the combination of the geomorphological and climatic settings of the region. The system is surrounded by ancient lagoon deposits with an extremely flat and low-lying topography, which favors the flooding of large extents. The large catchment area and the high precipitation rate over this region result in significant water level oscillations, causing the system to overflow and leading to subsequent floods.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.008
      Issue No: Vol. 117 (2018)
       
  • A new efficient implicit scheme for discretising the stiff friction terms
           in the shallow water equations
    • Authors: Xilin Xia; Qiuhua Liang
      Pages: 87 - 97
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Xilin Xia, Qiuhua Liang
      Discretisation of the friction terms to ensure numerical stability and accuracy remains to be challenging for the development of robust numerical schemes to solve the shallow water equations (SWEs), particularly for applications involving very shallow flows (e.g. overland flows and wet/dry fronts) over complex domain topography. The key challenge is to ensure relaxation of the flow towards an equilibrium state characterised by the balance between friction and gravity in a computationally efficient way. To overcome this numerical challenge, this paper proposes a novel approach for discretising the friction source terms in the SWEs in the context of an explicit finite volume method. The overall numerical scheme adopts the HLLC Riemann solver and surface reconstruction method (SRM) to explicitly discretise the flux and bed slope source terms. Whilst a fully implicit scheme is used to handle the friction source terms, solution to the implicit formulation is analytically derived to explicitly update the flow variables. Compared with the existing approaches, the proposed scheme effectively resolves the issue associated with stiff relaxation without necessity to use an iteration method and it supports efficient simulation using time steps controlled only by the Courant–Friedrichs–Levy (CFL) condition. The current friction term discretisation scheme is not coupled with flux and bed slope calculation and therefore may be readily implemented in any other explicit finite volume SWE models. After being successfully validated against two benchmark tests with analytical solutions, the resulting new SWE model is applied to reproduce a rainfall-flooding event in the Upper Lee catchment in the UK.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.004
      Issue No: Vol. 117 (2018)
       
  • Multi-phase SPH model for simulation of erosion and scouring by means of
           the shields and Drucker–Prager criteria.
    • Authors: Elizabeth H. Zubeldia; Georgios Fourtakas; Benedict D. Rogers; Márcio M. Farias
      Pages: 98 - 114
      Abstract: Publication date: July 2018
      Source:Advances in Water Resources, Volume 117
      Author(s): Elizabeth H. Zubeldia, Georgios Fourtakas, Benedict D. Rogers, Márcio M. Farias
      A two-phase numerical model using Smoothed Particle Hydrodynamics (SPH) is developed to model the scouring of two-phase liquid-sediments flows with large deformation. The rheology of sediment scouring due to flows with slow kinematics and high shear forces presents a challenge in terms of spurious numerical fluctuations. This paper bridges the gap between the non-Newtonian and Newtonian flows by proposing a model that combines the yielding, shear and suspension layer mechanics which are needed to predict accurately the local erosion phenomena. A critical bed-mobility condition based on the Shields criterion is imposed to the particles located at the sediment surface. Thus, the onset of the erosion process is independent on the pressure field and eliminates the numerical problem of pressure dependant erosion at the interface. This is combined with the Drucker–Prager yield criterion to predict the onset of yielding of the sediment surface and a concentration suspension model. The multi-phase model has been implemented in the open-source DualSPHysics code accelerated with a graphics processing unit (GPU). The multi-phase model has been compared with 2-D reference numerical models and new experimental data for scour with convergent results. Numerical results for a dry-bed dam break over an erodible bed shows improved agreement with experimental scour and water surface profiles compared to well-known SPH multi-phase models.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.04.011
      Issue No: Vol. 117 (2018)
       
  • On the accuracy of simulating mixing by random-walk particle-based
           mass-transfer algorithms
    • Authors: Michael J. Schmidt; Stephen D. Pankavich; David A. Benson
      Pages: 115 - 119
      Abstract: Publication date: Available online 9 May 2018
      Source:Advances in Water Resources
      Author(s): Michael J. Schmidt, Stephen D. Pankavich, David A. Benson
      Several algorithms have been used for mass transfer between particles undergoing advective and macro-dispersive random walks. The mass transfer between particles is required for general reactions on, and among, particles. The mass transfer is shown to be diffusive, and may be simulated using implicit, explicit, or mixed methods. All algorithms investigated are accurate to O ( Δ t ) . For N particles, the implicit and semi-implicit methods require inverse matrix solutions and O ( N 3 ) calculations. The explicit methods use forward matrix solves and require only O ( N 2 ) calculations. Practically, this means that naive implementations with more than about 5,000 particles run more reliably using explicit methods.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.003
      Issue No: Vol. 117 (2018)
       
  • Comparative 1D and 3D numerical investigation of open-channel junction
           flows and energy losses
    • Authors: Hao Luo; Dimitrios K. Fytanidis; Arthur R. Schmidt; Marcelo H. García
      Pages: 120 - 139
      Abstract: Publication date: Available online 21 May 2018
      Source:Advances in Water Resources
      Author(s): Hao Luo, Dimitrios K. Fytanidis, Arthur R. Schmidt, Marcelo H. García
      The complexity of open channel confluences stems from flow mixing, secondary circulation, post-confluence flow separation, contraction and backwater effects. These effects in turn result in a large number of parameters required to adequately quantify the junction induced hydraulic resistance and describe mean flow pattern and turbulent flow structures due to flow merging. The recent development in computing power advances the application of 3D Computational Fluid Dynamics (CFD) codes to visualize and understand the Confluence Hydrodynamic Zone (CHZ). Nevertheless, 1D approaches remain mainstay in large drainage network or waterway system modeling considering computational efficiency and data availability. This paper presents (i) a modified 1D nonlinear dynamic model; (ii) a fully 3D non-hydrostatic, Reynolds-averaged NavierâStokes Equations (RANS)-based, Computational Fluid Dynamics (CFD) model; (iii) an analysis of changing confluence hydrodynamics and 3D turbulent flow structure under various controls; (iv) a comparison of flow features (i.e. upstream water depths, energy losses and post-confluence contraction) predicted by 1D and 3D models; and (v) parameterization of 3D flow characteristics in 1D modeling through the computation of correction coefficients associated with contraction, energy and momentum. The present comprehensive 3D numerical investigation highlights the driving mechanisms for junction induced energy losses. Moreover, the comparative 1D and 3D study quantifies the deviation of 1D approximations and associated underlying assumptions from the ’true’ resultant flow field. The study may also shed light on improving the accuracy of the 1D large network modeling through parameterization of the complex 3D feature of the flow field and correction of interior boundary condition at junctions of larger angles and/or with substantial lateral inflows. Moreover, the enclosed numerical investigations may enhance the understanding of the primary mechanisms contributing to hydraulic structure induced turbulent flow behavior and increased hydraulic resistance.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.012
      Issue No: Vol. 117 (2018)
       
  • Evaluating the combined effects of source zone mass release rates and
           aquifer heterogeneity on solute discharge uncertainty
    • Authors: Felipe P.J. de Barros
      Pages: 140 - 150
      Abstract: Publication date: Available online 16 May 2018
      Source:Advances in Water Resources
      Author(s): Felipe P.J. de Barros
      Quantifying the uncertainty in solute mass discharge at an environmentally sensitive location is key to assess the risks due to groundwater contamination. Solute mass fluxes are strongly affected by the spatial variability of hydrogeological properties as well as release conditions at the source zone. This paper provides a methodological framework to investigate the interaction between the ubiquitous heterogeneity of the hydraulic conductivity and the mass release rate at the source zone on the uncertainty of mass discharge. Through the use of perturbation theory, we derive analytical and semi-analytical expressions for the statistics of the solute mass discharge at a control plane in a three-dimensional aquifer while accounting for the solute mass release rates at the source. The derived solutions are limited to aquifers displaying low-to-mild heterogeneity. Results illustrate the significance of the source zone mass release rate in controlling the mass discharge uncertainty. The relative importance of the mass release rate on the mean solute discharge depends on the distance between the source and the control plane. On the other hand, we find that the solute release rate at the source zone has a strong impact on the variance of the mass discharge. Within a risk context, we also compute the peak mean discharge as a function of the parameters governing the spatial heterogeneity of the hydraulic conductivity field and mass release rates at the source zone. The proposed physically-based framework is application-oriented, computationally efficient and capable of propagating uncertainty from different parameters onto risk metrics. Furthermore, it can be used for preliminary screening purposes to guide site managers to perform system-level sensitivity analysis and better allocate resources.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.010
      Issue No: Vol. 117 (2018)
       
  • Modelling coupled microbial processes in the subsurface: Model
           development, verification, evaluation and application
    • Authors: Shakil A. Masum; Hywel R. Thomas
      Pages: 1 - 17
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Shakil A. Masum, Hywel R. Thomas
      To study subsurface microbial processes, a coupled model which has been developed within a Thermal-Hydraulic-Chemical-Mechanical (THCM) framework is presented. The work presented here, focuses on microbial transport, growth and decay mechanisms under the influence of multiphase flow and bio-geochemical reactions. In this paper, theoretical formulations and numerical implementations of the microbial model are presented. The model has been verified and also evaluated against relevant experimental results. Simulated results show that the microbial processes have been accurately implemented and their impacts on porous media properties can be predicted either qualitatively or quantitatively or both. The model has been applied to investigate biofilm growth in a sandstone core that is subjected to a two-phase flow and variable pH conditions. The results indicate that biofilm growth (if not limited by substrates) in a multiphase system largely depends on the hydraulic properties of the medium. When the change in porewater pH which occurred due to dissolution of carbon dioxide gas is considered, growth processes are affected. For the given parameter regime, it has been shown that the net biofilm growth is favoured by higher pH; whilst the processes are considerably retarded at lower pH values. The capabilities of the model to predict microbial respiration in a fully coupled multiphase flow condition and microbial fermentation leading to production of a gas phase are also demonstrated.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.015
      Issue No: Vol. 116 (2018)
       
  • Resilience-based performance metrics for water resources management under
           uncertainty
    • Authors: Tom Roach; Zoran Kapelan; Ralph Ledbetter
      Pages: 18 - 28
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Tom Roach, Zoran Kapelan, Ralph Ledbetter
      This paper aims to develop new, resilience type metrics for long-term water resources management under uncertain climate change and population growth. Resilience is defined here as the ability of a water resources management system to ‘bounce back’, i.e. absorb and then recover from a water deficit event, restoring the normal system operation. Ten alternative metrics are proposed and analysed addressing a range of different resilience aspects including duration, magnitude, frequency and volume of related water deficit events. The metrics were analysed on a real-world case study of the Bristol Water supply system in the UK and compared with current practice. The analyses included an examination of metrics’ sensitivity and correlation, as well as a detailed examination into the behaviour of metrics during water deficit periods. The results obtained suggest that multiple metrics which cover different aspects of resilience should be used simultaneously when assessing the resilience of a water resources management system, leading to a more complete understanding of resilience compared with current practice approaches. It was also observed that calculating the total duration of a water deficit period provided a clearer and more consistent indication of system performance compared to splitting the deficit periods into the time to reach and time to recover from the worst deficit events.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.016
      Issue No: Vol. 116 (2018)
       
  • Attributing uncertainty in streamflow simulations due to variable inputs
           via the Quantile Flow Deviation metric
    • Authors: Syed Abu Shoaib; Lucy Marshall; Ashish Sharma
      Pages: 40 - 55
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Syed Abu Shoaib, Lucy Marshall, Ashish Sharma
      Every model to characterise a real world process is affected by uncertainty. Selecting a suitable model is a vital aspect of engineering planning and design. Observation or input errors make the prediction of modelled responses more uncertain. By way of a recently developed attribution metric, this study is aimed at developing a method for analysing variability in model inputs together with model structure variability to quantify their relative contributions in typical hydrological modelling applications. The Quantile Flow Deviation (QFD) metric is used to assess these alternate sources of uncertainty. The Australian Water Availability Project (AWAP) precipitation data for four different Australian catchments is used to analyse the impact of spatial rainfall variability on simulated streamflow variability via the QFD. The QFD metric attributes the variability in flow ensembles to uncertainty associated with the selection of a model structure and input time series. For the case study catchments, the relative contribution of input uncertainty due to rainfall is higher than that due to potential evapotranspiration, and overall input uncertainty is significant compared to model structure and parameter uncertainty. Overall, this study investigates the propagation of input uncertainty in a daily streamflow modelling scenario and demonstrates how input errors manifest across different streamflow magnitudes.

      PubDate: 2018-04-15T13:33:42Z
      DOI: 10.1016/j.advwatres.2018.01.022
      Issue No: Vol. 116 (2018)
       
  • Elucidating the impact of micro-scale heterogeneous bacterial distribution
           on biodegradation
    • Authors: Susanne I. Schmidt; Jan-Ulrich Kreft; Rae Mackay; Cristian Picioreanu; Martin Thullner
      Pages: 67 - 76
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Susanne I. Schmidt, Jan-Ulrich Kreft, Rae Mackay, Cristian Picioreanu, Martin Thullner
      Groundwater microorganisms hardly ever cover the solid matrix uniformly–instead they form micro-scale colonies. To which extent such colony formation limits the bioavailability and biodegradation of a substrate is poorly understood. We used a high-resolution numerical model of a single pore channel inhabited by bacterial colonies to simulate the transport and biodegradation of organic substrates. These high-resolution 2D simulation results were compared to 1D simulations that were based on effective rate laws for bioavailability-limited biodegradation. We (i) quantified the observed bioavailability limitations and (ii) evaluated the applicability of previously established effective rate concepts if microorganisms are heterogeneously distributed. Effective bioavailability reductions of up to more than one order of magnitude were observed, showing that the micro-scale aggregation of bacterial cells into colonies can severely restrict the bioavailability of a substrate and reduce in situ degradation rates. Effective rate laws proved applicable for upscaling when using the introduced effective colony sizes.

      PubDate: 2018-04-26T22:20:20Z
      DOI: 10.1016/j.advwatres.2018.01.013
      Issue No: Vol. 116 (2018)
       
  • Revisiting analytical solutions for steady interface flow in subsea
           aquifers: Aquitard salinity effects
    • Authors: Adrian D. Werner; Neville I. Robinson
      Pages: 117 - 126
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Adrian D. Werner, Neville I. Robinson
      Existing analytical solutions for the distribution of fresh groundwater in subsea aquifers presume that the overlying offshore aquitard, represented implicitly, contains seawater. Here, we consider the case where offshore fresh groundwater is the result of freshwater discharge from onshore aquifers, and neglect paleo-freshwater sources. A recent numerical modeling investigation, involving explicit simulation of the offshore aquitard, demonstrates that offshore aquitards more likely contain freshwater in areas of upward freshwater leakage to the sea. We integrate this finding into the existing analytical solutions by providing an alternative formulation for steady interface flow in subsea aquifers, whereby the salinity in the offshore aquitard can be chosen. The new solution, taking the aquitard salinity as that of freshwater, provides a closer match to numerical modeling results in which the aquitard is represented explicitly.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.01.002
      Issue No: Vol. 116 (2018)
       
  • Ecological and soil hydraulic implications of microbial responses to
           stress – A modeling analysis
    • Authors: Albert C. Brangarí; Daniel Fernàndez-Garcia; Xavier Sanchez-Vila; Stefano Manzoni
      Pages: 178 - 194
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Albert C. Brangarí, Daniel Fernàndez-Garcia, Xavier Sanchez-Vila, Stefano Manzoni
      A better understanding of microbial dynamics in porous media may lead to improvements in the design and management of a number of technological applications, ranging from the degradation of contaminants to the optimization of agricultural systems. To this aim, there is a recognized need for predicting the proliferation of soil microbial biomass (often organized in biofilms) under different environments and stresses. We present a general multi-compartment model to account for physiological responses that have been extensively reported in the literature. The model is used as an explorative tool to elucidate the ecological and soil hydraulic consequences of microbial responses, including the production of extracellular polymeric substances (EPS), the induction of cells into dormancy, and the allocation and reuse of resources between biofilm compartments. The mechanistic model is equipped with indicators allowing the microorganisms to monitor environmental and biological factors and react according to the current stress pressures. The feedbacks of biofilm accumulation on the soil water retention are also described. Model runs simulating different degrees of substrate and water shortage show that adaptive responses to the intensity and type of stress provide a clear benefit to microbial colonies. Results also demonstrate that the model may effectively predict qualitative patterns in microbial dynamics supported by empirical evidence, thereby improving our understanding of the effects of pore-scale physiological mechanisms on the soil macroscale phenomena.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2017.11.005
      Issue No: Vol. 116 (2018)
       
  • Accounting for model error in Bayesian solutions to hydrogeophysical
           inverse problems using a local basis approach
    • Authors: Corinna Köpke; James Irving; Ahmed H. Elsheikh
      Pages: 195 - 207
      Abstract: Publication date: June 2018
      Source:Advances in Water Resources, Volume 116
      Author(s): Corinna Köpke, James Irving, Ahmed H. Elsheikh
      Bayesian solutions to geophysical and hydrological inverse problems are dependent upon a forward model linking subsurface physical properties to measured data, which is typically assumed to be perfectly known in the inversion procedure. However, to make the stochastic solution of the inverse problem computationally tractable using methods such as Markov-chain-Monte-Carlo (MCMC), fast approximations of the forward model are commonly employed. This gives rise to model error, which has the potential to significantly bias posterior statistics if not properly accounted for. Here, we present a new methodology for dealing with the model error arising from the use of approximate forward solvers in Bayesian solutions to hydrogeophysical inverse problems. Our approach is geared towards the common case where this error cannot be (i) effectively characterized through some parametric statistical distribution; or (ii) estimated by interpolating between a small number of computed model-error realizations. To this end, we focus on identification and removal of the model-error component of the residual during MCMC using a projection-based approach, whereby the orthogonal basis employed for the projection is derived in each iteration from the K-nearest-neighboring entries in a model-error dictionary. The latter is constructed during the inversion and grows at a specified rate as the iterations proceed. We demonstrate the performance of our technique on the inversion of synthetic crosshole ground-penetrating radar travel-time data considering three different subsurface parameterizations of varying complexity. Synthetic data are generated using the eikonal equation, whereas a straight-ray forward model is assumed for their inversion. In each case, our developed approach enables us to remove posterior bias and obtain a more realistic characterization of uncertainty.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2017.11.013
      Issue No: Vol. 116 (2018)
       
  • Micro-positron emission tomography for measuring sub-core scale single and
           multiphase transport parameters in porous media
    • Authors: Christopher Zahasky; Sally M. Benson
      Pages: 1 - 16
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Christopher Zahasky, Sally M. Benson
      Accurate descriptions of heterogeneity in porous media are important for understanding and modeling single phase (e.g. contaminant transport, saltwater intrusion) and multiphase (e.g. geologic carbon storage, enhanced oil recovery) transport problems. Application of medical imaging to experimentally quantify these processes has led to significant progress in material characterization and understanding fluid transport behavior at laboratory scales. While widely utilized in cancer diagnosis and management, cardiology, and neurology, positron emission tomography (PET) has had relatively limited applications in earth science. This study utilizes a small-bore micro-PET scanner to image and quantify the transport behavior of pulses of a conservative aqueous radiotracer injected during single and multiphase flow experiments in two heterogeneous Berea sandstone cores. The cores are discretized into axial-parallel streamtubes, and using the reconstructed micro-PET data, expressions are derived from spatial moment analysis for calculating sub-core tracer flux and pore water velocity. Using the flux and velocity measurements, it is possible to calculate porosity and saturation from volumetric flux balance, and calculate permeability and water relative permeability from Darcy’s law. Second spatial moment analysis enables measurement of sub-core solute dispersion during both single phase and multiphase experiments. A numerical simulation model is developed to verify the assumptions of the streamtube dimension reduction technique. A variation of the reactor ratio is presented as a diagnostic metric to efficiently determine the validity of the streamtube approximation in core and column-scale experiments. This study introduces a new method to quantify sub-core permeability, relative permeability, and dispersion. These experimental and analytical methods provide a foundation for future work on experimental measurements of differences in transport behavior across scales.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.002
      Issue No: Vol. 115 (2018)
       
  • Entrainment, transport and deposition of sediment by saline gravity
           currents
    • Authors: Jessica Zordan; Carmelo Juez; Anton J. Schleiss; Mário J. Franca
      Pages: 17 - 32
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Jessica Zordan, Carmelo Juez, Anton J. Schleiss, Mário J. Franca
      Few studies have addressed simultaneously the feedback between the hydrodynamics of a gravity current and the geomorphological changes of a mobile bed. Hydrodynamic quantities such as turbulent and mean velocities, bed shear stress and turbulent stresses undoubtedly govern the processes of entrainment, transport and deposition. On the other hand, the incorporation of entrained sediment in the current may change its momentum by introducing extra internal stresses, introducing thus a feedback process. These two main questions are here investigated. Laboratory experiments of saline gravity currents, produced by lock-exchange, flowing over a mobile bed channel reach, are here reported. Different initial buoyancies of the current in the lock are tested together with three different grain sizes of the non-coherent sediment that form the erodible bed. Results from velocity measurements are combined with the visualization of the sediment movement in the mobile reach and with post-test topographic and photo surveys of the geomorphology modifications of the channel bed. Mean and turbulent velocities are measured and bed shear stress and Reynolds stresses are estimated. We show that the mean vertical component of the velocity and bed shear stress are highly correlated with the first instants of sediment entrainment. Vertical turbulent velocity is similarly related to entrainment, although with lower correlation values, contributing as well to the sediment movement. Bed shear stress and Reynolds shear stress measured near the bed are correlated with sediment entrainment for longer periods, indicating that these quantities are associated to distal transport as well. Geomorphological changes in the mobile bed are strongly related to the impulse caused by the bed shear stress on the sediment. On the other hand, we show that the nature of the grain of the mobile bed reach influences the hydrodynamics of the current which means that a feedback mechanisms between both occurs during the passage of the unsteady gravity current. The signature of this geomorphological changes, which is visible in the form of longitudinal steaks of accumulated sediment downstream the mobile bed, is related to the flow initial buoyancy and to the size of the mobile bed sediment. It is argued that the bed material and near-bed turbulent coherent motion interact and mutually influence each other. The geometry of the front of the gravity currents changes with the incorporation of the sediment, indicating that with the presence of sediment extra energy losses occur in the front of the current.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.02.017
      Issue No: Vol. 115 (2018)
       
  • Visualization of gas dissolution following upward gas migration in porous
           media: Technique and implications for stray gas
    • Authors: C.J.C. Van De Ven; Kevin G. Mumford
      Pages: 33 - 43
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): C.J.C. Van De Ven, Kevin G. Mumford
      The study of gas-water mass transfer in porous media is important in many applications, including unconventional resource extraction, carbon storage, deep geological waste storage, and remediation of contaminated groundwater, all of which rely on an understanding of the fate and transport of free and dissolved gas. The novel visual technique developed in this study provided both quantitative and qualitative observations of gas-water mass transfer. Findings included interaction between free gas architecture and dissolved plume migration, plume geometry and longevity. The technique was applied to the injection of CO2 in source patterns expected for stray gas originating from oil and gas operations to measure dissolved phase concentrations of CO2 at high spatial and temporal resolutions. The data set is the first of its kind to provide high resolution quantification of gas-water dissolution, and will facilitate an improved understanding of the fundamental processes of gas movement and fate in these complex systems.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.02.015
      Issue No: Vol. 115 (2018)
       
  • Morphological resilience to flow fluctuations of fine sediment deposits in
           bank lateral cavities
    • Authors: C. Juez; M. Thalmann; A.J. Schleiss; M.J. Franca
      Pages: 44 - 59
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): C. Juez, M. Thalmann, A.J. Schleiss, M.J. Franca
      Lateral cavities are built in the banks of rivers for several purposes: to create harbors, to capture sediment, to keep a central navigable channel (i.e., Casiers de Girardon in the Rhone river) or to promote the formation of aquatic habitats if a limited amount of sediment is captured, providing hydraulic and morphologic diversity (i.e., the case of Japanese Wandos). This work is focused on this latter purpose: promotion of hydraulic and morphologic diversity. In these scenarios, an increase in the flow discharge in the main channel may, however, re-mobilize the deposit of sediment inside these lateral embayments and cause a sudden increase of the sediment concentration and turbidity in the main channel. It is thus of interest to characterize the resistance and resilience of these sedimentary deposits when the main channel is subjected to high flow or flushing events. Laboratory tests were carried out for five different normalized geometries of the cavities installed in the banks of an open channel and for five hydrographs with different levels of unsteadiness. Water depth, sediment deposit mass, sediment concentration and area covered by the settled sediments were recorded throughout each experiment. Although sediment deposits established at equilibrium before the flushing events are different depending on the geometry of the cavities, generally, they are recovered after being flushed by the high flow events. It is shown that the resistance and resilience of the sediment deposits are strongly dependent on the flow field and the mass exchange between the main channel and the cavities. This mass exchange is governed by the geometry of the cavities and the magnitude of the hydrographs applied.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.004
      Issue No: Vol. 115 (2018)
       
  • Determination of the diffusivity, dispersion, skewness and kurtosis in
           heterogeneous porous flow. Part I: Analytical solutions with the extended
           method of moments.
    • Authors: Irina Ginzburg; Alexander Vikhansky
      Pages: 60 - 87
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Irina Ginzburg, Alexander Vikhansky
      The extended method of moments (EMM) is elaborated in recursive algorithmic form for the prediction of the effective diffusivity, the Taylor dispersion dyadic and the associated longitudinal high-order coefficients in mean-concentration profiles and residence-time distributions. The method applies in any streamwise-periodic stationary d-dimensional velocity field resolved in the piecewise continuous heterogeneous porosity field. It is demonstrated that EMM reduces to the method of moments and the volume-averaging formulation in microscopic velocity field and homogeneous soil, respectively. The EMM simultaneously constructs two systems of moments, the spatial and the temporal, without resorting to solving of the high-order upscaled PDE. At the same time, the EMM is supported with the reconstruction of distribution from its moments, allowing to visualize the deviation from the classical ADE solution. The EMM can be handled by any linear advection-diffusion solver with explicit mass-source and diffusive-flux jump condition on the solid boundary and permeable interface. The prediction of the first four moments is decisive in the optimization of the dispersion, asymmetry, peakedness and heavy-tails of the solute distributions, through an adequate design of the composite materials, wetlands, chemical devices or oil recovery. The symbolic solutions for dispersion, skewness and kurtosis are constructed in basic configurations: diffusion process and Darcy flow through two porous blocks in “series”, straight and radial Poiseuille flow, porous flow governed by the Stokes–Brinkman–Darcy channel equation and a fracture surrounded by penetrable diffusive matrix or embedded in porous flow. We examine the moments dependency upon porosity contrast, aspect ratio, Péclet and Darcy numbers, but also for their response on the effective Brinkman viscosity applied in flow modeling. Two numerical Lattice Boltzmann algorithms, a direct solver of the microscopic ADE in heterogeneous structure and a novel scheme for EMM numerical formulation, are called for validation of the constructed analytical predictions.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2017.12.005
      Issue No: Vol. 115 (2018)
       
  • Estimation of relative permeability and capillary pressure from mass
           imbibition experiments
    • Authors: Nayef Alyafei; Martin J. Blunt
      Pages: 88 - 94
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Nayef Alyafei, Martin J. Blunt
      We perform spontaneous imbibition experiments on three carbonates - Estaillades, Ketton, and Portland - which are three quarry limestones that have very different pore structures and span wide range of permeability. We measure the mass of water imbibed in air saturated cores as a function of time under strongly water-wet conditions. Specifically, we perform co-current spontaneous experiments using a highly sensitive balance to measure the mass imbibed as a function of time for the three rocks. We use cores measuring 37 mm in diameter and three lengths of approximately 76 mm, 204 mm, and 290 mm. We show that the amount imbibed scales as the square root of time and find the parameter C, where the volume imbibed per unit cross-sectional area at time t is Ct 1/2. We find higher C values for higher permeability rocks. Employing semi-analytical solutions for one-dimensional flow and using reasonable estimates of relative permeability and capillary pressure, we can match the experimental data. We finally discuss how, in combination with conventional measurements, we can use theoretical solutions and imbibition measurements to find or constrain relative permeability and capillary pressure.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.003
      Issue No: Vol. 115 (2018)
       
  • Fluid flow simulation and permeability computation in deformed porous
           carbonate grainstones
    • Authors: Miller Zambrano; Emanuele Tondi; Lucia Mancini; Gabriele Lanzafame; F. Xavier Trias; Fabio Arzilli; Marco Materazzi; Stefano Torrieri
      Pages: 95 - 111
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Miller Zambrano, Emanuele Tondi, Lucia Mancini, Gabriele Lanzafame, F. Xavier Trias, Fabio Arzilli, Marco Materazzi, Stefano Torrieri
      In deformed porous carbonates, the architecture of the pore network may be modified by deformation or diagenetic processes altering the permeability with respect to the pristine rock. The effects of the pore texture and morphology on permeability in porous rocks have been widely investigated due to the importance during the evaluation of geofluid reservoirs. In this study, these effects are assessed by combining synchrotron X-ray computed microtomography (SR micro-CT) and computational fluid dynamics. The studied samples pertain to deformed porous carbonate grainstones highly affected by deformation bands (DBs) exposed in Northwestern Sicily and Abruzzo regions, Italy. The high-resolution SR micro-CT images of the samples, acquired at the SYRMEP beamline of the Elettra - Sincrotrone Trieste laboratory (Italy), were used for simulating a pressure-driven flow by using the lattice-Boltzmann method (LBM). For the experiments, a multiple relaxation time (MRT) model with the D3Q19 scheme was used to avoid viscosity-dependent results of permeability. The permeability was calculated using Darcy's law once steady conditions were reached. After the simulations, the pore-network properties (effective porosity, specific surface area, and geometrical tortuosity) were calculated using 3D images of the velocity fields. These images were segmented considering a velocity threshold value higher than zero. The study showed that DBs may generate significant heterogeneity and anisotropy of the permeability of the evaluated rock samples. Cataclasis and cementation process taking place within the DBs reduce the effective porosity and therefore the permeability. Contrary to this, pressure dissolution and faulting may generate connected channels which contribute to the permeability only parallel to the DB.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.02.016
      Issue No: Vol. 115 (2018)
       
  • Optimization of image quality and acquisition time for lab-based X-ray
           microtomography using an iterative reconstruction algorithm
    • Authors: Qingyang Lin; Matthew Andrew; William Thompson; Martin J. Blunt; Branko Bijeljic
      Pages: 112 - 124
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Qingyang Lin, Matthew Andrew, William Thompson, Martin J. Blunt, Branko Bijeljic
      Non-invasive laboratory-based X-ray microtomography has been widely applied in many industrial and research disciplines. However, the main barrier to the use of laboratory systems compared to a synchrotron beamline is its much longer image acquisition time (hours per scan compared to seconds to minutes at a synchrotron), which results in limited application for dynamic in situ processes. Therefore, the majority of existing laboratory X-ray microtomography is limited to static imaging; relatively fast imaging (tens of minutes per scan) can only be achieved by sacrificing imaging quality, e.g. reducing exposure time or number of projections. To alleviate this barrier, we introduce an optimized implementation of a well-known iterative reconstruction algorithm that allows users to reconstruct tomographic images with reasonable image quality, but requires lower X-ray signal counts and fewer projections than conventional methods. Quantitative analysis and comparison between the iterative and the conventional filtered back-projection reconstruction algorithm was performed using a sandstone rock sample with and without liquid phases in the pore space. Overall, by implementing the iterative reconstruction algorithm, the required image acquisition time for samples such as this, with sparse object structure, can be reduced by a factor of up to 4 without measurable loss of sharpness or signal to noise ratio.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.007
      Issue No: Vol. 115 (2018)
       
  • An adaptive Gaussian process-based iterative ensemble smoother for data
           assimilation
    • Authors: Lei Ju; Jiangjiang Zhang; Long Meng; Laosheng Wu; Lingzao Zeng
      Pages: 125 - 135
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Lei Ju, Jiangjiang Zhang, Long Meng, Laosheng Wu, Lingzao Zeng
      Accurate characterization of subsurface hydraulic conductivity is vital for modeling of subsurface flow and transport. The iterative ensemble smoother (IES) has been proposed to estimate the heterogeneous parameter field. As a Monte Carlo-based method, IES requires a relatively large ensemble size to guarantee its performance. To improve the computational efficiency, we propose an adaptive Gaussian process (GP)-based iterative ensemble smoother (GPIES) in this study. At each iteration, the GP surrogate is adaptively refined by adding a few new base points chosen from the updated parameter realizations. Then the sensitivity information between model parameters and measurements is calculated from a large number of realizations generated by the GP surrogate with virtually no computational cost. Since the original model evaluations are only required for base points, whose number is much smaller than the ensemble size, the computational cost is significantly reduced. The applicability of GPIES in estimating heterogeneous conductivity is evaluated by the saturated and unsaturated flow problems, respectively. Without sacrificing estimation accuracy, GPIES achieves about an order of magnitude of speed-up compared with the standard IES. Although subsurface flow problems are considered in this study, the proposed method can be equally applied to other hydrological models.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.010
      Issue No: Vol. 115 (2018)
       
  • Porous gravity currents: Axisymmetric propagation in horizontally graded
           medium and a review of similarity solutions
    • Authors: I. Lauriola; G. Felisa; D. Petrolo; V. Di Federico; S. Longo
      Pages: 136 - 150
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): I. Lauriola, G. Felisa, D. Petrolo, V. Di Federico, S. Longo
      We present an investigation on the combined effect of fluid rheology and permeability variations on the propagation of porous gravity currents in axisymmetric geometry. The fluid is taken to be of power-law type with behaviour index n and the permeability to depend from the distance from the source as a power-law function of exponent β. The model represents the injection of a current of non-Newtonian fluid along a vertical bore hole in porous media with space-dependent properties. The injection is either instantaneous ( α = 0 ) or continuous (α > 0). A self-similar solution describing the rate of propagation and the profile of the current is derived under the assumption of small aspect ratio between the current average thickness and length. The limitations on model parameters imposed by the model assumptions are discussed in depth, considering currents of increasing/decreasing velocity, thickness, and aspect ratio, and the sensitivity of the radius, thickness, and aspect ratio to model parameters. Several critical values of α and β discriminating between opposite tendencies are thus determined. Experimental validation is performed using shear-thinning suspensions and Newtonian mixtures in different regimes. A box filled with ballotini of different diameter is used to reproduce the current, with observations from the side and bottom. Most experimental results for the radius and profile of the current agree well with the self-similar solution except at the beginning of the process, due to the limitations of the 2-D assumption and to boundary effects near the injection zone. The results for this specific case corroborate a general model for currents with constant or time-varying volume of power-law fluids propagating in porous domains of plane or radial geometry, with uniform or varying permeability, and the possible effect of channelization. All results obtained in the present and previous papers for the key parameters governing the dynamics of power-law gravity currents are summarized and compared to infer the combinations of parameters leading to the fastest/lowest rate of propagation, and of variation of thickness and aspect ratio.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.008
      Issue No: Vol. 115 (2018)
       
  • Impact of microstructure evolution on the difference between geometric and
           reactive surface areas in natural chalk
    • Authors: Y. Yang; S. Bruns; S.L.S. Stipp; H.O. Sørensen
      Pages: 151 - 159
      Abstract: Publication date: May 2018
      Source:Advances in Water Resources, Volume 115
      Author(s): Y. Yang, S. Bruns, S.L.S. Stipp, H.O. Sørensen
      The coupling between flow and mineral dissolution drives the evolution of many natural and engineered flow systems. Pore surface changes as microstructure evolves but this transient behaviour has traditionally been difficult to model. We combined a reactor network model with experimental, greyscale tomography data to establish the morphological grounds for differences among geometric, reactive and apparent surface areas in dissolving chalk. This approach allowed us to study the effects of initial geometry and macroscopic flow rate independently. The simulations showed that geometric surface, which represents a form of local transport heterogeneity, increases in an imposed flow field, even when the porous structure is chemically homogeneous. Hence, the fluid-reaction coupling leads to solid channelisation, which further results in fluid focusing and an increase in geometric surface area. Fluid focusing decreases the area of reactive surface and the residence time of reactant, both contribute to the over-normalisation of reaction rate. In addition, the growing and merging of microchannels, near the fluid entrance, contribute to the macroscopic, fast initial dissolution rate of rocks.
      Graphical abstract image

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.005
      Issue No: Vol. 115 (2018)
       
  • Wake structure and sediment deposition behind models of submerged
           vegetation with and without flexible leaves
    • Abstract: Publication date: Available online 15 June 2018
      Source:Advances in Water Resources
      Author(s): Zhenghong Hu, Jiarui Lei, Chao Liu, Heidi Nepf
      This laboratory study explored the flow structure and pattern of the deposition directly downstream of submerged patches of vegetation, focusing on whether, or not, the presence of flexible trailing leaves enhanced deposition. Both leaves of different length and patches of different geometry (circular and channel-spanning) were considered. The study defined the length of wake within which the velocity was diminished and net deposition was enhanced. The model sediment represented an organic or mineral solid smaller than fine sand. For a channel-spanning, submerged patch, recirculation or turbulent diffusion in the x-z (streamwise-vertical) plane set the wake length within which velocity was diminished and deposition was enhanced. This length was greater for patches with lower stem densities, because greater flow through the patch displaced the recirculating eddy farther downstream. In addition, for a channel-spanning patch, the presence of flexible trailing leaves extended the wake length, which in turn increased the length of the deposition region. In contrast, for a circular patch, the wake contained oscillations in the x-y (streamwise – lateral) plane. The onset of the wake unsteadiness set the length of the deposition region. Because the presence of flexible trailing leaves on a circular patch did not affect the formation distance for the wake oscillation, the length of the deposition region was unchanged with the addition of the flexible trailing leaves. For both circular and channel-spanning patches, a longer deposition region was associated with a larger deposition mass.

      PubDate: 2018-06-18T23:06:04Z
       
  • Considering the utility of backward-in-time simulations of multi-component
           reactive transport in porous media
    • Abstract: Publication date: Available online 15 June 2018
      Source:Advances in Water Resources
      Author(s): Nicholas B. Engdahl, Tomás Aquino
      Indirect inversion has been the predominant method for matching models and data in geochemical systems, typically using observations of chemical concentrations as calibration targets. This reserves the data with the highest confidence (observed concentrations) for the final comparison but does little to constrain the initial state of the system on which the indirect inversion is based. An alternative approach to inverse modeling is to start with the observations to reconstruct a concentration field, but it is unclear if this is feasible for reactive transport in heterogeneous systems. The purpose of this article is to consider the applicability of backward-in-time (BIT) techniques as tools for simulating reactive transport in porous media. A multi-component reaction system is considered in a variety of systems of increasing complexity and we show that complex, non-linear systems can be simulated backward in time, given a sufficiently robust integration scheme. Recent advances in reactive random walk particle tracking are employed to investigate simple flow systems with spatially variable reactions, as well as 2-d heterogeneous flows, and we show that some level of time reversibility exists in both cases. Under a uniform injection scheme, the total masses generated in forward and backward simulations of the 2-d models were all within 3.5% of each other for all the species considered, indicating good overall agreement between the models. This suggests that BIT techniques may have yet unrealized applications to inverse modeling; however, further research on the sensitivity of the approach to measurement errors and on how to efficiently apply BIT methods to transient problems is needed.

      PubDate: 2018-06-18T23:06:04Z
       
  • Effective permeability of three-dimensional porous media containing
           anisotropic distributions of oriented elliptical disc-shaped fractures
           with uniform aperture
    • Authors: Minh-Ngoc Vu; Amade Pouya; Darius M. Seyedi
      Abstract: Publication date: Available online 1 June 2018
      Source:Advances in Water Resources
      Author(s): Minh-Ngoc Vu, Amade Pouya, Darius M. Seyedi
      Solution for the fluid potential within a fractured porous medium is described. This solution is derived numerically for the particular case of a Pouseuille's elliptical fracture plane with uniform aperture. A closed-form solution of total flow integrated over a single fracture is obtained as a function of matrix permeability, fracture permeability and fracture geometry parameters. This solution allows firstly the comparison between two approaches: Poiseuille's fracture and Darcy's flattened ellipsoidal inclusion. This shows the difference of pressure and flow fields in the fractures and the equivalence of total flow transported by fractures. Then, a semi-analytical solution is used to establish an effective permeability model based on the self-consistent scheme for a porous medium containing an anisotropic distribution of oriented elliptical plane fractures. The proposed model is in good agreement with numerical solutions reported in the literature for a random distribution of oriented fractures. The present model exhibits a percolation threshold for a three-dimensional fractured network. The percolation threshold is a critical value of fracture density, beyond which the effective permeability is greater than zero for the case of an impermeable parent material.

      PubDate: 2018-06-04T09:30:37Z
      DOI: 10.1016/j.advwatres.2018.05.014
       
  • A Learning-based Data-driven Forecast Approach for Predicting Future
           Reservoir Performance
    • Authors: Hoonyoung Jeong; Alexander Y. Sun; Jonghyun Lee; Baehyun Min
      Abstract: Publication date: Available online 31 May 2018
      Source:Advances in Water Resources
      Author(s): Hoonyoung Jeong, Alexander Y. Sun, Jonghyun Lee, Baehyun Min
      Quantification of the predictive uncertainty of subsurface models has long been investigated. The traditional workflow is to calibrate prior models to match observed data, and then use the posterior models to simulate future system performance. Not only are these procedures computationally expensive, but they also have issues in maintaining geological model constraints during the calibration step. Data space inversion (DSI) was introduced recently to predict future system performance without the iterative history matching or model calibration step. In general, DSI approaches seek to establish a statistical relationship between the observed and forecast variables, as well as to quantify the predictive uncertainty of the forecast variables, by using an ensemble of uncalibrated prior models. Existing DSI approaches all require a number of complex transformation and mapping operations, which may deter their widespread use. In this study, we introduce a new and simpler DSI approach, the learning-based, data-driven forecast approach (LDFA), by combining dimension reduction and machine learning techniques to quickly provide accurate forecast results and reliably quantify corresponding uncertainty in the results. Our LDFA framework is demonstrated using two supervised learning algorithms, artificial neural network (ANN) and support vector regression (SVR), on two representative examples from reservoir engineering and geological carbon storage. Results suggest that our approach provides accurate forecast results (e.g., future oil production rate or cumulative injected CO2) and reasonable predictive uncertainty intervals. Our framework is generic and may be applied to other surface and subsurface problems.

      PubDate: 2018-06-01T09:25:15Z
      DOI: 10.1016/j.advwatres.2018.05.015
       
  • Event-based model calibration approaches for selecting representative
           distributed parameters in semi-urban watersheds
    • Authors: Frezer Seid Awol; Paulin Coulibaly; Bryan A. Tolson
      Abstract: Publication date: Available online 24 May 2018
      Source:Advances in Water Resources
      Author(s): Frezer Seid Awol, Paulin Coulibaly, Bryan A. Tolson
      The objective of this study is to propose an event-based calibration approach for selecting representative semi-distributed hydrologic model parameters and to enhance peak flow prediction at multiple sites of a semi-urban catchment. The performance of three multi-site calibration approaches (multi-site simultaneous (MS-S), multi-site average objective function (MS-A) and multi-event multi-site (ME-MS)) and a benchmark at-catchment outlet (OU) calibration method, are compared in this study. Additional insightful contributions include assessing the nature of the spatio-temporal parameter variability among calibration events and developing an advanced event-based calibration approach to identify skillful model parameter-sets. This study used a SWMM5 hydrologic model in the Humber River Watershed located in Southern Ontario, Canada. For MS-S and OU calibration methods, the multi-objective calibration formulation is solved with the Pareto Archived Dynamically Dimensioned Search (PA-DDS) algorithm. For the MS-A and ME-MS methods, the single objective calibration formulation is solved with the Dynamically Dimensioned Search (DDS) algorithm. The results indicate that the MS-A calibration approach achieved better performance than other considered methods. Comparison between optimized model parameter sets showed that the DDS optimization in MS-A approach improved the model performance at multiple sites. The spatial and temporal variability analysis indicates a presence of uncertainty on sensitive parameters and most importantly on peak flow responses in an event-based calibration process. This finding implied the need to evaluate potential model parameters sets with a series of calibration steps as proposed herein. The proposed calibration and optimization formulation successfully identified representative model parameter set, which is more skillful than what is attainable when using simultaneous multi-site (MS-S), multi-event multi-site (MS-ME) or at basin outlet (OU) approach.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.013
       
  • Adaptive Water Infrastructure Planning for Nonstationary Hydrology
    • Authors: Rui Hui; Jonathan Herman; Jay Lund; Kaveh Madani
      Abstract: Publication date: Available online 18 May 2018
      Source:Advances in Water Resources
      Author(s): Rui Hui, Jonathan Herman, Jay Lund, Kaveh Madani
      The uncertainty of a changing climate raises challenges for water infrastructure planning and design. Not accounting for nonstationarity may result in under-designed structures that fail too frequently, or over-designed structures that are economically inefficient. This concern is magnified by uncertainty in the long-term frequency and magnitude of future extreme events. Planning strategies that allow adaptations over a structure's life could improve both reliability and economic efficiency. This study develops a method to inform adaptive water infrastructure planning with uncertain hydrologic and other forms of nonstationarity, applied to levee system planning. A stochastic dynamic programming model including a Markov process is developed for infrastructure planning with uncertain nonstationarity in flood frequency. Bayes' theorem is used to update peak flow probabilities conditioned on observed past peak flows and to update expected residual flood damages over time. A levee system planning problem with a numerical example from California illustrates the approach to derive optimal levee heights over time, and economic values of adapting to uncertain nonstationary flood risk. The projected range of probabilistic hydrology scenarios affects the optimal results, particularly in later planning stages as hydrology scenarios diverge with time. Adaptive planning strategies allowing more levee upgrades over time slightly lowers the overall cost and provides better flood protection than one-time construction under nonstationary hydrology for any climate in the example. Compared to a known future nonstationary hydrology, incorporating uncertain nonstationary climate results in higher levees being planned for observed severe hydrology scenarios in later stages. The overall present value cost with uncertain nonstationary climate depends on rates of change in peak flow distribution parameters in future hydrology scenarios.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.009
       
  • RIVER PROCESSES AND LINKS BETWEEN FLUVIAL AND COASTAL SYSTEMS IN A
           CHANGING CLIMATE
    • Authors: Donatella Termini
      Abstract: Publication date: Available online 17 May 2018
      Source:Advances in Water Resources
      Author(s): Donatella Termini


      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.05.011
       
  • Pattern-Based Calibration of Complex Subsurface Flow Models against
           Dynamic Response Data
    • Authors: Azarang Golmohammadi; Mohammad-Reza M. Khaninezhad; Behnam Jafarpour
      Abstract: Publication date: Available online 6 May 2018
      Source:Advances in Water Resources
      Author(s): Azarang Golmohammadi, Mohammad-Reza M. Khaninezhad, Behnam Jafarpour
      Calibration of heterogeneous subsurface flow models usually leads to ill-posed nonlinear inverse problems, where too many unknown parameters are estimated from limited response measurements. When the underlying parameters form complex (non-Gaussian) structured spatial connectivity patterns, classical variogram-based geostatistical techniques cannot describe the underlying distributions. Modern pattern-based geostatistical methods that incorporate higher-order spatial statistics are more suitable for describing such complex spatial patterns. Moreover, when the unknown parameters are discrete (e.g., geologic facies distribution), conventional model calibration techniques that are designed for continuous parameters cannot be applied directly. In this paper, we introduce a novel pattern-based model calibration method to reconstruct spatially complex facies distributions from dynamic flow response data. To reproduce complex connectivity patterns during model calibration, we impose a geologic feasibility constraint that ensures the solution honors the expected higher-order spatial statistics. For model calibration, we adopt a regularized least-squares formulation, involving (i) data mismatch, (ii) pattern connectivity, and (iii) feasibility constraint terms. Using an alternating directions optimization algorithm, the regularized objective function is divided into a parameterized model calibration sub-problem, which is solved via gradient-based optimization. The resulting parameterized solution is then mapped onto the feasible set, using the k nearest neighbors (kNN) as a supervised machine learning approach, to honor the expected spatial statistics. The two steps of the model calibration formulation are repeated until the convergence criterion is met. Several numerical examples are used to evaluate the performance of the developed method.

      PubDate: 2018-05-28T16:50:14Z
      DOI: 10.1016/j.advwatres.2018.04.007
       
  • Pore scale study of multiphase multicomponent reactive transport during
           CO2 dissolution trapping
    • Authors: Li Chen; Mengyi Wang; Qinjun Kang; Wenquan Tao
      Abstract: Publication date: Available online 26 April 2018
      Source:Advances in Water Resources
      Author(s): Li Chen, Mengyi Wang, Qinjun Kang, Wenquan Tao
      Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3 −, CO3 2− and OH−) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.

      PubDate: 2018-04-26T22:20:20Z
      DOI: 10.1016/j.advwatres.2018.04.010
       
  • Investigating the Influence of Flow Rate on Biofilm Growth in Three
           Dimensions using Microimaging
    • Authors: Sassan Ostvar; Gabriel Iltis; Yohan Davit; Steffen Schlüter; Linnéa Andersson; Brian D. Wood; Dorthe Wildenschild
      Abstract: Publication date: Available online 26 April 2018
      Source:Advances in Water Resources
      Author(s): Sassan Ostvar, Gabriel Iltis, Yohan Davit, Steffen Schlüter, Linnéa Andersson, Brian D. Wood, Dorthe Wildenschild
      We explore how X-ray computed microtomography can be used to generate highly-resolved 3D biofilm datasets on length scales that span multiple pore bodies. The data is integrated into a study of the effects of flow rate on three-dimensional growth of biofilm in porous media. Three flow rates were investigated in model packed-bed columns. Biofilm growth was monitored during an 11-day growth period using a combination of differential pressure and effluent dissolved oxygen measurements. At the end of the growth period, all columns were scanned using X-ray computed microtomography and a barium sulfate-based contrast agent. The resulting images were prepared for quantitative analysis using a novel image processing workflow that was tailored to this specific system. The reduction in permeability due to biofilm growth was studied using both transducer-based pressure drop measurements and image-based calculations using the Kozeny-Carman model. In addition, a set of structural measures related to the spatial distribution of biofilms were computed and analyzed for the different flow rates. We generally observed 1 to 2 orders of magnitude decrease in permeability as a result of bioclogging for all columns (i.e, across flow rates). The greatest average permeability and porosity reduction was observed for the intermediate flow rate (4.5 ml/hr). A combination of results from different measurements all suggest that biofilm growth was oxygen limited at the lowest flow rate, and affected by shear stresses at the highest flow rate. We hypothesize that the interplay between these two factors drives the spatial distribution and quantity of biofilm growth in the class of porous media studied here. Our approach opens the way to more systematic studies of the structure-function relationships involved in biofilm growth in porous media and the impact that such growth may have on physical properties such as hydraulic conductivity.

      PubDate: 2018-04-26T22:20:20Z
      DOI: 10.1016/j.advwatres.2018.03.018
       
  • A lattice Boltzmann investigation of steady-state fluid distribution,
           capillary pressure and relative permeability of a porous medium: effects
           of fluid and geometrical properties
    • Authors: Zi Li; Sergio Galindo-Torres; Guanxi Yan; Alexander Scheuermann; Ling Li
      Abstract: Publication date: Available online 24 April 2018
      Source:Advances in Water Resources
      Author(s): Zi Li, Sergio Galindo-Torres, Guanxi Yan, Alexander Scheuermann, Ling Li
      Simulations of simultaneous steady-state two-phase flow in the capillary force-dominated regime were conducted using the state-of-the-art Shan-Chen multi-component lattice Boltzmann model (SCMC-LBM) based on two-dimensional porous media. We focused on analysing the fluid distribution (i.e., WP fluid-solid, NP fluid-solid and fluid-fluid interfacial areas) as well as the capillary pressure versus saturation curve which was affected by fluid and geometrical properties (i.e., wettability, adhesive strength, pore size distribution and specific surface area). How these properties influenced the relative permeability versus saturation relation through apparent effective permeability and threshold pressure gradient was also explored. The SCMC-LBM simulations showed that, a thin WP fluid film formed around the solid surface due to the adhesive fluid-solid interaction, resulting in discrete WP fluid distributions and reduction of the WP fluid mobility. Also, the adhesive interaction provided another source of capillary pressure in addition to capillary force, which, however, did not affect the mobility of the NP fluid. The film fluid effect could be enhanced by large adhesive strength and fine pores in heterogeneous porous media. In the steady-state infiltration, not only the NP fluid but also the WP fluid were subjected to the capillary resistance. The capillary pressure effect could be alleviated by decreased wettability, large average pore radius and improved fluid connectivity in heterogeneous porous media. The present work based on the SCMC-LBM investigations elucidated the role of film fluid as well as capillary pressure in the two-phase flow system. The findings have implications for ways to improve the macroscopic flow equation based on balance of force for the steady-state infiltration.

      PubDate: 2018-04-26T22:20:20Z
      DOI: 10.1016/j.advwatres.2018.04.009
       
  • Evaluating Drywells for Stormwater Management and Enhanced Aquifer
           Recharge
    • Authors: Salini Sasidharan; Scott A. Bradford; Jiří Šimůnek; Bill DeJong; Stephen R. Kraemer
      Abstract: Publication date: Available online 14 April 2018
      Source:Advances in Water Resources
      Author(s): Salini Sasidharan, Scott A. Bradford, Jiří Šimůnek, Bill DeJong, Stephen R. Kraemer
      Drywells are increasingly used for stormwater management and enhanced aquifer recharge, but only limited research has quantitatively determined the performance of drywells. Numerical and field scale experiments were, therefore, conducted to improve our understanding and ability to characterize the drywell behavior. In particular, HYDRUS (2D/3D) was modified to simulate transient head boundary conditions for the complex geometry of the Maxwell Type IV drywell; i.e., a sediment chamber, an overflow pipe, and the variable geometry and storage of the drywell system with depth. Falling-head infiltration experiments were conducted on drywells located at the National Training Center in Fort Irwin, California (CA) and a commercial complex in Torrance, CA to determine in situ soil hydraulic properties (the saturated hydraulic conductivity, Ks , and the retention curve shape parameter, α) for an equivalent uniform soil profile by inverse parameter optimization. A good agreement between the observed and simulated water heights in wells was obtained for both sites as indicated by the Pearson correlation coefficients of 95-99%, unique parameter fits, and small standard errors. Fort Irwin and Torrance drywells had very distinctive soil hydraulic characteristics. The fitted value of Ks =1.01 × 10−3 m min−1 at the Torrance drywell was consistent with the sandy soil texture at this site and the default value for sand in the HYDRUS soil catalog. The drywell with this Ks = 1.01 × 10−3 m min−1 could easily infiltrate predicted surface runoff from a design rain event (∼51.3 m3) within 5760 min (4 d). In contrast, the fitted value of Ks=2.25 × 10−6 m min−1 at Fort Irwin was very low compared to the Torrance drywell and more than an order of magnitude smaller than the default value reported in the HYDRUS soil catalog for sandy clay loam at this site, likely due to clogging. These experiments and simulations provide useful information to characterize effective soil hydraulic properties in situ, and to improve the design of drywells for enhanced recharge.
      Graphical abstract image

      PubDate: 2018-04-15T13:33:42Z
      DOI: 10.1016/j.advwatres.2018.04.003
       
  • Joint analysis of input and parametric uncertainties in watershed water
           quality modeling: a formal Bayesian approach
    • Authors: Feng Han; Yi Zheng
      Abstract: Publication date: Available online 13 April 2018
      Source:Advances in Water Resources
      Author(s): Feng Han, Yi Zheng
      Significant Input uncertainty is a major source of error in watershed water quality (WWQ) modeling. It remains challenging to address the input uncertainty in a rigorous Bayesian framework. This study develops the Bayesian Analysis of Input and Parametric Uncertainties (BAIPU), an approach for the joint analysis of input and parametric uncertainties through a tight coupling of Markov Chain Monte Carlo (MCMC) analysis and Bayesian Model Averaging (BMA). The formal likelihood function for this approach is derived considering a lag-1 autocorrelated, heteroscedastic, and Skew Exponential Power (SEP) distributed error model. A series of numerical experiments were performed based on a synthetic nitrate pollution case and on a real study case in the Newport Bay Watershed, California. The Soil and Water Assessment Tool (SWAT) and Differential Evolution Adaptive Metropolis (DREAM(ZS)) were used as the representative WWQ model and MCMC algorithm, respectively. The major findings include the following: 1) the BAIPU can be implemented and used to appropriately identify the uncertain parameters and characterize the predictive uncertainty; 2) the compensation effect between the input and parametric uncertainties can seriously mislead the modeling based management decisions, if the input uncertainty is not explicitly accounted for; 3) the BAIPU accounts for the interaction between the input and parametric uncertainties and therefore provides more accurate calibration and uncertainty results than a sequential analysis of the uncertainties; and 4) the BAIPU quantifies the credibility of different input assumptions on a statistical basis and can be implemented as an effective inverse modeling approach to the joint inference of parameters and inputs.

      PubDate: 2018-04-15T13:33:42Z
      DOI: 10.1016/j.advwatres.2018.04.006
       
  • A Series Solution for Horizontal Infiltration in an Initially Dry Aquifer
    • Authors: Eden Furtak-Cole; Aleksey S. Telyakovskiy; Clay A. Cooper
      Abstract: Publication date: Available online 12 April 2018
      Source:Advances in Water Resources
      Author(s): Eden Furtak-Cole, Aleksey S. Telyakovskiy, Clay A. Cooper
      The porous medium equation (PME) is a generalization of the traditional Boussinesq equation for hydraulic conductivity as a power law function of height. We analyze the horizontal recharge of an initially dry unconfined aquifer of semi-infinite extent, as would be found in an aquifer adjacent a rising river. If the water level can be modeled as a power law function of time, similarity variables can be introduced and the original problem can be reduced to a boundary value problem for a nonlinear ordinary differential equation. The position of the advancing front is not known ahead of time and must be found in the process of solution. We present an analytical solution in the form of a power series, with the coefficients of the series given by a recurrence relation. The analytical solution compares favorably with a highly accurate numerical solution, and only a small number of terms of the series are needed to achieve high accuracy in the scenarios considered here. We also conduct a series of physical experiments in an initially dry wedged Hele-Shaw cell, where flow is modeled by a special form of the PME. Our analytical solution closely matches the hydraulic head profiles in the Hele-Shaw cell experiment.

      PubDate: 2018-04-15T13:33:42Z
      DOI: 10.1016/j.advwatres.2018.04.005
       
  • Hydro-Power Production and Fish Habitat Suitability: Assessing Impact and
           Effectiveness of Ecological Flows at Regional Scale
    • Authors: Serena Ceola; Alessio Pugliese; Matteo Ventura; Giorgio Galeati; Alberto Montanari; Attilio Castellarin
      Abstract: Publication date: Available online 5 April 2018
      Source:Advances in Water Resources
      Author(s): Serena Ceola, Alessio Pugliese, Matteo Ventura, Giorgio Galeati, Alberto Montanari, Attilio Castellarin
      Anthropogenic activities along streams and rivers may be of major concern for fluvial ecosystems, e.g. abstraction and impoundment of surface water resources may profoundly alter natural streamflow regimes. An established approach aimed at preserving the behavior and distribution of fluvial species relies on the definition of ecological flows (e-flows) downstream of dams and diversion structures. E-flow prescriptions are usually set by basin authorities at regional scale, often without a proper assessment of their impact and effectiveness. On the contrary, we argue that e-flows should be identified on the basis of (i) regional and (ii) quantitative assessments. We focus on central Italy and evaluate the effects on habitat suitability of two near-threatened fish species (i.e. Barbel and Chub) and an existing hydro-power network when shifting from the current time-invariant e-flow policy to a tighter and seasonally-varying soon-to-be-enforced one. Our example clearly shows that: (a) quantitative regional scale assessments are viable even when streamflow observations are entirely missing at study sites; (b) aprioristic e-flows policies may impose releases that exceed natural streamflows for significantly long time intervals (weeks, or months); (c) unduly tightening e-flow policies may heavily impact regional hydro-power productivity (15% and 42% losses on annual and seasonal basis, respectively), yet resulting in either marginal or negligible improvements of fluvial ecosystem.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.04.002
       
  • IMAGING & COMPUTATIONAL CONSIDERATIONS FOR IMAGE COMPUTED
           PERMEABILITY: OPERATING ENVELOPE OF DIGITAL ROCK PHYSICS
    • Authors: Nishank Saxena; Amie Hows; Ronny Hofmann; Faruk O. Alpak; Justin Freeman; Sander Hunter; Matthias Appel
      Abstract: Publication date: Available online 4 April 2018
      Source:Advances in Water Resources
      Author(s): Nishank Saxena, Amie Hows, Ronny Hofmann, Faruk O. Alpak, Justin Freeman, Sander Hunter, Matthias Appel
      This study defines the optimal operating envelope of the Digital Rock technology from the perspective of imaging and numerical simulations of transport properties. Imaging larger volumes of rocks for Digital Rock Physics (DRP) analysis improves the chances of achieving a Representative Elementary Volume (REV) at which flow-based simulations (1) do not vary with change in rock volume, and (2) is insensitive to the choice of boundary conditions. However, this often comes at the expense of image resolution. This trade-off exists due to the finiteness of current state-of-the-art imaging detectors. Imaging and analyzing digital rocks that sample the REV and still sufficiently resolve pore throats is critical to ensure simulation quality and robustness of rock property trends for further analysis. We find that at least 10 voxels are needed to sufficiently resolve pore throats for single phase fluid flow simulations. If this condition is not met, additional analyses and corrections may allow for meaningful comparisons between simulation results and laboratory measurements of permeability, but some cases may fall outside the current technical feasibility of DRP. On the other hand, we find that the ratio of field of view and effective grain size provides a reliable measure of the REV for siliciclastic rocks. If this ratio is greater than 5, the coefficient of variation for single-phase permeability simulations drops below 15 %. These imaging considerations are crucial when comparing digitally computed rock flow properties with those measured in the laboratory. We find that the current imaging methods are sufficient to achieve both REV (with respect to numerical boundary conditions) and required image resolution to perform digital core analysis for coarse to fine-grained sandstones.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.04.001
       
  • A Numerical Study of the Complex Flow Structure in a Compound Meandering
           Channel
    • Authors: Ignacio J. Moncho-Esteve; Guillermo Palau-Salvador; Manuel García-Villalba; Yasu Muto; Koji Shiono
      Abstract: Publication date: Available online 21 March 2018
      Source:Advances in Water Resources
      Author(s): Ignacio J. Moncho-Esteve, Guillermo Palau-Salvador, Manuel García-Villalba, Yasu Muto, Koji Shiono
      In this study, we report large eddy simulations of turbulent flow in a periodic compound meandering channel for three different depth conditions: one in-bank and two overbank conditions. The flow configuration corresponds to the experiments of Shiono and Muto (1998). The predicted mean streamwise velocities, mean secondary motions, velocity fluctuations, turbulent kinetic energy as well as mean flood flow angle to meandering channel are in good agreement with the experimental measurements. We have analyzed the flow structure as a function of the inundation level, with particular emphasis on the development of the secondary motions due to the interaction between the main channel and the floodplain flow. Bed shear stresses have been also estimated in the simulations. Floodplain flow has a significant impact on the flow structure leading to significantly different bed shear stress patterns within the main meandering channel. The implications of these results for natural compound meandering channels are also discussed.

      PubDate: 2018-04-11T01:51:15Z
      DOI: 10.1016/j.advwatres.2018.03.013
       
 
 
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