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Showing 1 - 200 of 3043 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 20, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 18, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 83, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 23, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 332, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 1)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 211, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 23, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 4, SJR: 0.383, h-index: 19)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 2)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 3)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 8, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 129, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 25, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 25, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
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: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 41, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 40, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 47, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 35, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 5)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
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: 4)
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: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 60)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 2, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 345, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 7, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 30, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 15)
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: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 43, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 309, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 5, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 8, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 405, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 38, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 53, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 9, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 6)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 8, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 4, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 7, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 48, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 48, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 45, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 38, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 16, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 31, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 24, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 33, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 46, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 191, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 54, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 3)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 23, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 26, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 34, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 55, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 10)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 162, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 158, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (Followers: 1, SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Advances in Water Resources
  [SJR: 2.408]   [H-I: 94]   [43 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0309-1708
   Published by Elsevier Homepage  [3043 journals]
  • SPH modelling of multi-fluid lock-exchange over and within porous media
    • Authors: Hossein Basser; Murray Rudman; Edoardo Daly
      Pages: 15 - 28
      Abstract: Publication date: October 2017
      Source:Advances in Water Resources, Volume 108
      Author(s): Hossein Basser, Murray Rudman, Edoardo Daly
      Multi-fluid flow over and within porous media occurs frequently in nature and plays an important role in engineering applications. The modeling of these flows and validation against experimental or field observations have not been largely conducted in literature. An explicit numerical scheme for incompressible fluid using Smoothed Particle Hydrodynamics (EISPH) was employed and solved using two integration algorithms. To explore the capabilities and limitations of the model, case studies including percolation of a single fluid in a porous medium, gravity current of a single fluid over a porous medium, multi-fluid flow over an impermeable bed, and a porous medium were simulated and compared with experimental data. The EISPH method led to results overall similar to the observed experimental data. The model was able to reproduce the behaviour of the flow within media with different porosities. In addition, the model reproduced behaviour of multi-fluid flow at the interface between different fluids, such as reproducing Kelvin–Helmholtz vortices and diffusion of salt.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.07.011
      Issue No: Vol. 108 (2017)
  • Improved streamflow recession parameter estimation with attention to
           calculation of − dQ/dt
    • Authors: Clément Roques; David E. Rupp; John S. Selker
      Pages: 29 - 43
      Abstract: Publication date: October 2017
      Source:Advances in Water Resources, Volume 108
      Author(s): Clément Roques, David E. Rupp, John S. Selker
      The rate of streamflow recession can be used to assess storage-outflow properties of source aquifers. A common method of analyzing streamflow recession is to plot the time rate of change in streamflow Q as a function of Q in a log-log space. Theory predicts, for diagnostic recession regimes, a power law relationship − dQ/dt = aQb , where recession coefficients a and b are functions of the hydraulic and geometric properties of the aquifer and of boundary and initial conditions. Observational error reduces the accuracy of estimates of a and b with errors in estimating the time derivative of the late-time recession (−dQ/dt) being particularly sensitive to observational error. Here we propose a method to improve estimation of a and b with particular focus on the estimation of −dQ/dt. Compared to previously published methods we find greater robustness in estimates of −dQ/dt and recession parameters and less sensitivity to the methodological parameters employed. Previous methods result in up to 50 to 100% error when estimating the recession parameter b, while the proposed methodology produces errors below 5% in the cases analyzed.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.07.013
      Issue No: Vol. 108 (2017)
  • Sediment exchange between groin fields and main-stream
    • Authors: Jie Qin; Deyu Zhong; Teng Wu; Lingli Wu
      Pages: 44 - 54
      Abstract: Publication date: Available online 25 July 2017
      Source:Advances in Water Resources
      Author(s): Jie Qin, Deyu Zhong, Teng Wu, Lingli Wu
      Sediment exchange between groin fields and the main-stream influences the transport and distribution of polluted sediment that represents a hazard for rivers and neighboring floodplains. Despite its practical significance, little research has been done on the sediment exchange process itself, and existing studies used to estimate the sediment exchange by morphological change. The sediment exchange process, however, differs from morphological variation and includes two behaviors: the entrance of main-stream sediment into groin fields and the movement of groin field sediment out of groin fields. Therefore, this study aims at examining this exchange process and exploring the mechanisms of different exchange phenomena. Experiments were conducted in a mobile-bed laboratory flume by using a novel experimental method that successfully separates the movement of groin fields sediment from that of main-stream sediment. In addition to traditional measurements, such as measurements of morphological changes, surface flow velocities, and bed-form propagation, the deposition of main-stream sediment in groin fields is measured in detail. The results demonstrate that morphological change cannot reflect the sediment exchange process. The deposition of main-stream sediment in groin fields is determined by the dynamics of sediment movement, in which bedload- and suspended-sediment-dominated processes exhibit different deposition patterns. The movement of groin field sediment out of groin fields is determined mainly by local scouring around groins.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.07.015
      Issue No: Vol. 108 (2017)
  • Multiscale mimetic method for two-phase flow in fractured media using
           embedded discrete fracture model
    • Authors: Qingfu Zhang; Zhaoqin Huang; Jun Yao; Yueying Wang; Yang Li
      Pages: 180 - 190
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Qingfu Zhang, Zhaoqin Huang, Jun Yao, Yueying Wang, Yang Li
      A multiscale mimetic method is developed for the simulation of multiphase flow in fractured porous media in the context of an embedded discrete fracture model (EDFM). The EDFM constructs independent grids for matrix and fracture system. Therefore, it is an efficient and practical flow model as it avoids the complicated unstructured grid subdivision and computing process. In order to extend the EDFM to field-scale applications, we integrate EDFM into a multiscale mimetic method. In this work, we use the multiscale basis functions to capture the detailed interactions between the fractures and the background. The multiscale basis functions are calculated numerically by solving EDFM on the local fine-grid with mimetic finite difference (MFD) method. The MFD method is conservative and robust, which makes it possible to deal with highly complex grid systems. Through combination of multiscale mimetic method and EDFM, this formulation can generate accurate velocity field and pressure field on the fine-scale grid more efficiently than the traditional methods. Numerical results are presented for verification of this multiscale mimetic approach for embedded discrete fracture media, and demonstrate its computational efficiency. The results show that this method is an accurate and efficient method for flow simulation in real-field fractured heterogeneous reservoirs.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.020
      Issue No: Vol. 107 (2017)
  • Dynamic pore-scale network model (PNM) of water imbibition in porous media
    • Authors: J. Li; S.R. McDougall; K.S. Sorbie
      Pages: 191 - 211
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): J. Li, S.R. McDougall, K.S. Sorbie
      A dynamic pore-scale network model is presented which simulates 2-phase oil/water displacement during water imbibition by explicitly modelling intra-pore dynamic bulk and film flows using a simple local model. A new dynamic switching parameter, λ, is proposed within this model which is able to simulate the competition between local capillary forces and viscous forces over a very wide range of flow conditions. This quantity (λ) determines the primary pore filling mechanism during imbibition; i.e. whether the dominant force is (i) piston-like displacement under viscous forces, (ii) film swelling/collapse and snap-off due to capillary forces, or (iii) some intermediate local combination of both mechanisms. A series of 2D dynamic pore network simulations is presented which shows that the λ-model can satisfactorily reproduce and explain different filling regimes of water imbibition over a wide range of capillary numbers (Ca) and viscosity ratios (M). These imbibition regimes are more complex than those presented under drainage by (Lenormand et al. (1983)), since they are determined by a wider group of control parameters. Our simulations show that there is a coupling between viscous and capillary forces that is much less important in drainage. The effects of viscosity ratio during imbibition are apparent even under conditions of very slow flow (low Ca)–displacements that would normally be expected to be completely capillary dominated. This occurs as a result of the wetting films having a much greater relative mobility in the higher M cases (e.g. M = 10) thus leading to a higher level of film swelling/snap-off, resulting in local oil cluster bypassing and trapping, and hence a poorer oil recovery. This deeper coupled viscous mechanism is the underlying reason why the microscopic displacement efficiency is lower for higher M cases in water imbibition processes. Additional results are presented from the dynamic model on the corresponding effluent fractional flows (fw ) and global pressure drops (ΔP) as functions of capillary number and viscosity ratio. These results indicate that unsteady-state (USS) relatively permeabilities in imbibition should be inherently rate dependent.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.017
      Issue No: Vol. 107 (2017)
  • A 1D–2D Shallow Water Equations solver for discontinuous porosity field
           based on a Generalized Riemann Problem
    • Authors: Alessia Ferrari; Renato Vacondio; Susanna Dazzi; Paolo Mignosa
      Pages: 233 - 249
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Alessia Ferrari, Renato Vacondio, Susanna Dazzi, Paolo Mignosa
      A novel augmented Riemann Solver capable of handling porosity discontinuities in 1D and 2D Shallow Water Equation (SWE) models is presented. With the aim of accurately approximating the porosity source term, a Generalized Riemann Problem is derived by adding an additional fictitious equation to the SWEs system and imposing mass and momentum conservation across the porosity discontinuity. The modified Shallow Water Equations are theoretically investigated, and the implementation of an augmented Roe Solver in a 1D Godunov-type finite volume scheme is presented. Robust treatment of transonic flows is ensured by introducing an entropy fix based on the wave pattern of the Generalized Riemann Problem. An Exact Riemann Solver is also derived in order to validate the numerical model. As an extension of the 1D scheme, an analogous 2D numerical model is also derived and validated through test cases with radial symmetry. The capability of the 1D and 2D numerical models to capture different wave patterns is assessed against several Riemann Problems with different wave patterns.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.023
      Issue No: Vol. 107 (2017)
  • Modelling capillary hysteresis effects on preferential flow through
           melting and cold layered snowpacks
    • Authors: Nicolas R. Leroux; John W. Pomeroy
      Pages: 250 - 264
      Abstract: Publication date: Available online 1 July 2017
      Source:Advances in Water Resources
      Author(s): Nicolas R. Leroux, John W. Pomeroy
      Accurate estimation of the amount and timing of water flux through melting snowpacks is important for runoff prediction in cold regions. Most existing snowmelt models only account for one-dimensional matrix flow and neglect to simulate the formation of preferential flow paths. Consideration of lateral and preferential flows has proven critical to improve the performance of soil and groundwater porous media flow models. A two-dimensional physically-based snowpack model that simulates snowmelt, refreezing of meltwater, heat and water flows, and preferential flow paths is presented. The model assumes thermal equilibrium between solid and liquid phases and uses recent snow physics advances to estimate snowpack hydraulic and thermal properties. For the first time, capillary hysteresis is accounted in a snowmelt model. A finite volume method is applied to solve for the 2D coupled heat and mass transfer equations. The model with capillary hysteresis provided better simulations of water suction at the wet to dry snow interface in a wetting snow sample than did a model that only accounted for the boundary drying curve. Capillary hysteresis also improved simulations of preferential flow path dynamics and the snowpack discharge hydrograph. Simulating preferential flow in a subfreezing snowpack allowed the model to generate ice layers, and increased the vertical exchange of energy, thus modelling a faster warming of the snowpack than would be possible without preferential flow. The model is thus capable of simulating many attributes of heterogeneous natural melting snowpacks. These features not only qualitatively improve water flow simulations, but improve the understanding of snowmelt flow processes for both level and sloping terrain, and illuminate how uncertainty in snowmelt-derived runoff calculations might be reduced through the inclusion of more realistic preferential flow through snowpacks.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.024
      Issue No: Vol. 107 (2017)
  • Using helicopter TEM to delineate fresh water and salt water zones in the
           aquifer beneath the Okavango Delta, Botswana
    • Authors: Joel E. Podgorski; Wolfgang K.H. Kinzelbach; Lesego Kgotlhang
      Pages: 265 - 279
      Abstract: Publication date: Available online 4 July 2017
      Source:Advances in Water Resources
      Author(s): Joel E. Podgorski, Wolfgang K.H. Kinzelbach, Lesego Kgotlhang
      The Okavango Delta is a vast wetland wilderness in the middle of the Kalahari Desert of Botswana. It is a largely closed hydrological system with most water leaving the delta by evapotranspiration. In spite of this, the channels and swamps of the delta remain surprisingly low in salinity. To help understand the hydrological processes at work, we reanalyzed a previous inversion of data collected from a helicopter transient electromagnetic (HTEM) survey of the entire delta and performed an inversion of a high resolution dataset recorded during the same survey. Our results show widespread infiltration of fresh water to as much as ∼200 m depth into the regional saline aquifer. Beneath the western delta, freshwater infiltration extends to only about 80 m depth. Hydrological modeling with SEAWAT confirms that this may be due to rebound of the regional saltwater-freshwater interface following the cessation of surface flooding over this part of the delta in the 1880s. Our resistivity models also provide evidence for active and inactive saltwater fingers to as much as ∼100 m beneath islands. These results demonstrate the great extent of freshwater infiltration across the delta and also show that all vegetated areas along the delta's channels and swamps are potential locations for transferring solutes from surface water to an aquifer at depth.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.021
      Issue No: Vol. 107 (2017)
  • Pore Network Extraction for Fractured Porous Media
    • Authors: Z. Jiang; M.I.J. van Dijke; S. Geiger; J. Ma; G.D. Couples; X. Li
      Pages: 280 - 289
      Abstract: Publication date: Available online 4 July 2017
      Source:Advances in Water Resources
      Author(s): Z. Jiang, M.I.J. van Dijke, S. Geiger, J. Ma, G.D. Couples, X. Li
      Although flow through fractured rocks involves many different length-scales, it is crucial for the prediction of continuum-scale single- and multi-phase flow functions to understand, at the pore-scale, the interaction between the rock matrix and fractures. Here we present a pore-network extraction method in which the pore diameters and fracture apertures are of similar size. The method involves a shrinking algorithm to extract a hybrid skeleton of medial axes and surfaces, and it includes a workflow to convert the medial surfaces of fractures into dense networks of virtual medial axes, allowing generation of an integrated pore-network for the entire pore space. Appropriate single- and two-phase flow properties are assigned to network elements representing the fractures. We validate the method via comparisons between pore network flow simulations and an analytical solution, direct flow simulations and experimental observations. The network calculations are several orders of magnitude faster than the direct simulations.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.06.025
      Issue No: Vol. 107 (2017)
  • Multivariate regional frequency analysis: Two new methods to increase the
           accuracy of measures
    • Authors: Amin Abdi; Yousef Hassanzadeh; Siamak Talatahari; Ahmad Fakheri-Fard; Rasoul Mirabbasi; Taha B.M.J. Ouarda
      Pages: 290 - 300
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Amin Abdi, Yousef Hassanzadeh, Siamak Talatahari, Ahmad Fakheri-Fard, Rasoul Mirabbasi, Taha B.M.J. Ouarda
      The accurate detection of discordant sites in a heterogeneous region and the estimation of the regional parameters of a statistical distribution are two important issues in multivariate regional frequency analysis. In this study, two new methods are proposed for increasing the accuracy of the multivariate l-moment approach. The first one, the optimization-based method (OBM) is utilized to estimate the best distribution parameters. The second one is the rank-based method (RBM), which is used in the robust discordancy measure for identifying discordant sites. In order to assess the performance of the proposed approaches on the heterogeneity measure, real and simulated regions of drought characteristics are considered. The results confirm the usefulness of the new methods in comparison with some well-established techniques.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.006
      Issue No: Vol. 107 (2017)
  • A generalized Forchheimer radial flow model for constant-rate tests
    • Authors: Ming-Ming Liu; Yi-Feng Chen; Hongbin Zhan; Ran Hu; Chuang-Bing Zhou
      Pages: 317 - 325
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Ming-Ming Liu, Yi-Feng Chen, Hongbin Zhan, Ran Hu, Chuang-Bing Zhou
      Models used for data interpretation of constant-rate tests (CRTs) are commonly derived with the assumption of Darcian flow in an idealized integer flow dimension, where the non-Darcian nature of fluid flow and the complexity of flow geometry are disregarded. In this study, a Forchheimer's law-based analytical model is proposed with the assumption of buildup (or drawdown) decomposition for characterizing the non-Darcian flow in a generalized radial formation where the flow dimension n may become non-integer. The proposed model immediately reduces to Barker's (1988) model for Darcian flow in the generalized radial formation and to Mathias et al.'s (2008) model for non-Darcian flow in a two-dimensional confined aquifer. A comparison with numerical simulations shows that the proposed model behaves well at late times for flow dimension n > 1.5. The proposed model is finally applied for data interpretation of the constant-rate pumping tests performed at Ploemeur (Le Borgne et al., 2004), showing that the intrinsic hydraulic conductivity of formations will be underestimated and the specific storage will be overestimated if the non-Darcian effect is ignored. The proposed model is an extension of the generalized radial flow (GRF) model based on Forchheimer's law, which would be of significance for data interpretation of CRTs in aquifers of complex flow geometry in which non-Darcian flow occurs.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.004
      Issue No: Vol. 107 (2017)
  • Coastal morphodynamical modelling in nonlinear shallow water framework
           using a coordinate transformation method
    • Authors: Van Long Huynh; Nicholas Dodd; Fangfang Zhu
      Pages: 326 - 335
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Van Long Huynh, Nicholas Dodd, Fangfang Zhu
      A 1D numerical model of Nonlinear Shallow Water Equations (NSWEs) coupled to an advection equation for suspended sediment and a bed evolution equation is developed. The moving boundary at the shoreline is treated by a coordinate transformation method (CTM). An absorbing-generating seaward boundary condition in the transformed variables is also developed. The purely hydrodynamic component (NSWEs) is verified against analytical results. The NSWEs plus advection equation is verified quasi-analytical results. The fully-coupled model with bed change due to bed-load is verified against a single swash event and long-term numerical simulation. Excellent agreement is observed in all verifications.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.003
      Issue No: Vol. 107 (2017)
  • Integrated meteorological and hydrological drought model: A management
           tool for proactive water resources planning of semi-arid regions
    • Authors: Arash Modaresi Rad; Bijan Ghahraman; Davar Khalili; Zahra Ghahremani; Samira Ahmadi Ardakani
      Pages: 336 - 353
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Arash Modaresi Rad, Bijan Ghahraman, Davar Khalili, Zahra Ghahremani, Samira Ahmadi Ardakani
      Conventionally, drought analysis has been limited to single drought category. Utilization of models incorporating multiple drought categories, can relax this limitation. A copula-based model is proposed, which uses meteorological and hydrological drought characteristics to assess drought events for ultimate management of water resources, at small scales, i.e., sub-watersheds. The chosen study area is a sub-basin located at Karkheh watershed (western Iran), with five raingauge stations and one hydrometric station, located upstream and at the outlet, respectively, which represent 41-year of data. Prior to drought analysis, time series of precipitation and streamflow records are investigated for possible dependency/significant trend. Considering semi-arid nature of the study area, boxplots are utilized to graphically capture the rainy months, which are used to evaluate the degree of correlation between streamflow and precipitation records via nonparametric correlations. Time scales of 3- and 12-month are considered, which are used to study vulnerability of early vegetation establishment and long-term ecosystem resilience, respectively. Among four common goodness of fit (GOF) tests, Anderson–Darling is found preferable for defining copula distribution functions through GOF measures, i.e., Akaike and Bayesian information criteria and normalized root mean square error. Furthermore, a GOF method is proposed to evaluate the uncertainty associated with different copula models using the concept of entropy. A new bivariate drought modeling approach is proposed through copulas. The proposed index named standardized precipitation-streamflow index (SPSI) unlike common indices which are used in conjunction with station data, can be applied on a regional basis. SPDI is compared with widely applied streamflow drought index (SDI) and standardized precipitation index (SPI). To assess the homogeneity of the dependence structure of SPSI regionally, Kendall-τ and upper tail coefficient relation is investigated for all stations located within the region. According to results, SPSI similar to nonparametric multivariate standardized drought index (NMSDI) was able to detect both onset of droughts dominated by precipitation as is similarly indicated by SPI and persistence of droughts dominated by streamflow as is similarly indicated by SDI. It also captures discordant case of normal period precipitation with dry period streamflow and vice versa. This makes SPSI a powerful tool for estimating a more practical and realistic drought condition. Finally, combination of severity–duration–frequency (SDF) of drought events through copulas resulted in SDF curves that can be used to obtain the recurrence of extreme droughts and assess drought related ecosystem failure or to aid in optimization of water resources allocation. Results indicated that the newly proposed index (SPSI) is able to represent two main characteristics of meteorological and hydrological drought (drought onset and persistency) and also providing an accurate estimation of the recurrence interval of extreme droughts. The procedures can be used to undertake proactive water resource management and planning to assure water security and sustainable agriculture and ecosystem survival for regions experiencing extreme droughts.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.007
      Issue No: Vol. 107 (2017)
  • Characterising the dynamics of surface water-groundwater interactions in
           intermittent and ephemeral streams using streambed thermal signatures
    • Authors: Gabriel C. Rau; Landon J.S. Halloran; Mark O. Cuthbert; Martin S. Andersen; R. Ian Acworth; John H. Tellam
      Pages: 354 - 369
      Abstract: Publication date: September 2017
      Source:Advances in Water Resources, Volume 107
      Author(s): Gabriel C. Rau, Landon J.S. Halloran, Mark O. Cuthbert, Martin S. Andersen, R. Ian Acworth, John H. Tellam
      Ephemeral and intermittent flow in dryland stream channels infiltrates into sediments, replenishes groundwater resources and underpins riparian ecosystems. However, the spatiotemporal complexity of the transitory flow processes that occur beneath such stream channels are poorly observed and understood. We develop a new approach to characterise the dynamics of surface water-groundwater interactions in dryland streams using pairs of temperature records measured at different depths within the streambed. The approach exploits the fact that the downward propagation of the diel temperature fluctuation from the surface depends on the sediment thermal diffusivity. This is controlled by time-varying fractions of air and water contained in streambed sediments causing a contrast in thermal properties. We demonstrate the usefulness of this method with multi-level temperature and pressure records of a flow event acquired using 12 streambed arrays deployed along a  ∼ 12 km dryland channel section. Thermal signatures clearly indicate the presence of water and characterise the vertical flow component as well as the occurrence of horizontal hyporheic flow. We jointly interpret thermal signatures as well as surface and groundwater levels to distinguish four different hydrological regimes: [A] dry channel, [B] surface run-off, [C] pool-riffle sequence, and [D] isolated pools. The occurrence and duration of the regimes depends on the rate at which the infiltrated water redistributes in the subsurface which, in turn, is controlled by the hydraulic properties of the variably saturated sediment. Our results have significant implications for understanding how transitory flows recharge alluvial sediments, influence water quality and underpin dryland ecosystems.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.005
      Issue No: Vol. 107 (2017)
  • Hydrology of soils and aquifers: A special issue in honor of Garrison
    • Authors: WeiCheng Lo; Philippe C. Baveye; Laurent Charlet
      Pages: 1 - 2
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): WeiCheng Lo, Philippe C. Baveye, Laurent Charlet

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.05.008
      Issue No: Vol. 106 (2017)
  • Global land surface evaporation trend during the past half century:
           Corroboration by Clausius-Clapeyron scaling
    • Authors: Wilfried Brutsaert
      Pages: 3 - 5
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Wilfried Brutsaert
      Analyses of satellite data mainly over the world's ocean surfaces have shown that during 1986–2006 global average values of atmospheric water vapor, precipitation and evaporation have increased at a relative rate of 0.0013 a − 1 ; this is roughly in accordance with the Clausius-Clapeyron equation for the average temperature trend during this period, and amounts to 0.065 K − 1 at the average temperature of T = 14 ∘ C . Application of this concept over the world's land surfaces yields an average global evaporation trend during the past half century of around 0.4 to 0.5 mm a − 2 ; this confirms the values obtained in previous studies with totally different methods.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2016.08.014
      Issue No: Vol. 106 (2017)
  • Solute plumes mean velocity in aquifer transport: Impact of injection and
           detection modes
    • Authors: Gedeon Dagan
      Pages: 6 - 10
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Gedeon Dagan
      Flow of mean velocity U takes place in a heterogeneous aquifer of random spatially variable conductivity K. A solute plume is injected instantaneously along a plane normal to U, over a large area relative to the logconductivity integral scale I (ergodic plume). Transport is by advection by the spatially variable Eulerian velocity. The study is focused on the derivation of the mean plume velocity in the four modes set forth by Kreft and Zuber [1978] for one dimensional flow in a homogeneous medium. In the resident injection mode the mass is initially distributed uniformly in space while in the flux mode it is proportional to the local velocity. In the resident detection mode the mean velocity pertains to the plume centroid, whereas in flux detection it is quantified with the aid of the BTC and the corresponding mean arrival time. In agreement with the literature, it is shown that URR and UFF , pertaining to same injection and detection modes, either resident or flux, are equal to U. In contrast, in the mixed modes the solute velocity may differ significantly from U near the injection plane, approaching it at large distances relative to I. These effects are explained qualitatively with the aid of the exact solution for stratified aquifers.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2016.09.014
      Issue No: Vol. 106 (2017)
  • Teaching and communicating dispersion in hydrogeology, with emphasis on
           the applicability of the Fickian model
    • Authors: P.K. Kitanidis
      Pages: 11 - 23
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): P.K. Kitanidis
      The process of dispersion in porous media is the effect of combined variability in fluid velocity and concentration at scales smaller than the ones resolved that contributes to spreading and mixing. It is usually introduced in textbooks and taught in classes through the Fick-Scheidegger parameterization, which is introduced as a scientific law of universal validity. This parameterization is based on observations in bench-scale laboratory experiments using homogeneous media. Fickian means that dispersive flux is proportional to the gradient of the resolved concentration while the Scheidegger parameterization is a particular way to compute the dispersion coefficients. The unresolved scales are thus associated with the pore-grain geometry that is ignored when the composite pore-grain medium is replaced by a homogeneous continuum. However, the challenge faced in practice is how to account for dispersion in numerical models that discretize the domain into blocks, often cubic meters in size, that contain multiple geologic facies. Although the Fick-Scheidegger parameterization is by far the one most commonly used, its validity has been questioned. This work presents a method of teaching dispersion that emphasizes the physical basis of dispersion and highlights the conditions under which a Fickian dispersion model is justified. In particular, we show that Fickian dispersion has a solid physical basis provided that an equilibrium condition is met. The issue of the Scheidegger parameterization is more complex but it is shown that the approximation that the dispersion coefficients should scale linearly with the mean velocity is often reasonable, at least as a practical approximation, but may not necessarily be always appropriate. Generally in Hydrogeology, the Scheidegger feature of constant dispersivity is considered as a physical law and inseparable from the Fickian model, but both perceptions are wrong. We also explain why Fickian dispersion fails under certain conditions, such as dispersion inside and directly upstream of a contaminant source. Other issues discussed are the relevance of column tests and confusion regarding the meaning of terms dispersion and Fickian.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.01.006
      Issue No: Vol. 106 (2017)
  • Sugar-influenced water diffusion, interaction, and retention in clay
           interlayer nanopores probed by theoretical simulations and experimental
    • Authors: Ludmilla Aristilde; Stephen M. Galdi; Sabrina E. Kelch; Thalia G. Aoki
      Pages: 24 - 38
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Ludmilla Aristilde, Stephen M. Galdi, Sabrina E. Kelch, Thalia G. Aoki
      Understanding the hydrodynamics in clay nanopores is important for gaining insights into the trapping of water, nutrients, and contaminants in natural and engineered soils. Previous investigations have focused on the interlayer organization and molecular diffusion coefficients (D) of cations and water molecules in cation-saturated interlayer nanopores of smectite clays. Little is known, however, about how these interlayer dynamic properties are influenced by the ubiquitous presence of small organic compounds such as sugars in the soil environment. Here we probed the effects of glucose molecules on montmorillonite interlayer properties. Molecular dynamics simulations revealed re-structuring of the interlayer organization of the adsorptive species. Water-water interactions were disrupted by glucose-water H-bonding interactions. “Dehydration” of the glucose-populated nanopore led to depletion in the Na solvation shell, which resulted in the accumulation of both Na ions (as inner-sphere complexes) and remaining hydrated water molecules at the mineral surface. This accumulation led to a decrease in both D Na and D water. In addition, the reduction in D glucose as a function of increasing glucose content can be explained by the aggregation of glucose molecules into organic clusters H-bonded to the mineral surface on both walls of the nanopore. Experimental nuclear magnetic resonance and X-ray diffraction data were consistent with the theoretical predictions. Compared to clay interlayers devoid of glucose, increased intensities and new peaks in the 23Na nuclear magnetic resonance spectra confirmed increasing immobilization of Na as a function of increasing glucose content. And, the X-ray diffraction data indicated a reduced collapse of glucose-populated interlayers exposed to decreasing moisture conditions, which led to the maintenance of hydrated clay nanopores. The coupling of theoretical and experimental findings sheds light on the molecular to nanoscale mechanisms that control the enhanced trapping of water molecules and solutes within sugar-enriched clay nanopores.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.014
      Issue No: Vol. 106 (2017)
  • Diffusive transport and reaction in clay rocks: A storage (nuclear waste,
           CO2, H2), energy (shale gas) and water quality issue
    • Authors: Laurent Charlet; Peter Alt-Epping; Paul Wersin; Benjamin Gilbert
      Pages: 39 - 59
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Laurent Charlet, Peter Alt-Epping, Paul Wersin, Benjamin Gilbert
      Clay rocks are low permeability sedimentary formations that provide records of Earth history, influence the quality of water resources, and that are increasingly used for the extraction or storage of energy resources and the sequestration of waste materials. Informed use of clay rock formations to achieve low-carbon or carbon-free energy goals requires the ability to predict the rates of diffusive transport processes for chemically diverse dissolved and gaseous species over periods up to thousands of years. We survey the composition, properties and uses of clay rock and summarize fundamental science challenges in developing confident conceptual and quantitative gas and solute transport models.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.019
      Issue No: Vol. 106 (2017)
  • Water infiltration into prewetted porous media: Dynamic capillary pressure
           and Green-Ampt modeling
    • Authors: Shao-Yiu Hsu; Vincent Huang; Sang Woo Park; Markus Hilpert
      Pages: 60 - 67
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Shao-Yiu Hsu, Vincent Huang, Sang Woo Park, Markus Hilpert
      Experimental studies have shown that the modified Green-Ampt (GA) model, which accounts for a velocity-dependent capillary pressure, can describe water infiltration into dry sand columns better than the classical GA model. In this study, we performed a series of downward water infiltration experiments in prewetted sand columns for four different initial water contents (0, 3.3, 6.5 and 13.8%) and three different ponding heights (10, 20 and 40 cm). As expected, an increase in ponding height resulted in a monotonic increase in the infiltration rate. The infiltration rate decreased monotonically as the initial water content increased for initial water contents of 3.3, 6.5 and 13.8%. However, the infiltration rate in the dry sand columns was significantly smaller than in the prewetted sand columns. We linked this anomalous behavior to the strong dynamic effect of the capillary pressure on water infiltration into dry sand columns. The series of downward infiltration experiments were modeled by both the classical and modified GA models. The modified GA model can describe better the experimental results than the classical GA model for infiltration into both dry and prewetted sand columns. The modeling and parameter fitting results show that the magnitude of the dynamic effect on the capillary pressure depends on the initial water content and decreases exponentially as the initial water content increases. Consequently, the classical GA model significantly underestimates the equilibrium suction heads for the infiltration experiments in the dry sand columns.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.02.017
      Issue No: Vol. 106 (2017)
  • Flow dynamics in vadose zones with and without vegetation in an arid
    • Authors: Wenke Wang; Zaiyong Zhang; Tian-chyi Jim Yeh; Gang Qiao; Wenmin Wang; Lei Duan; Shao-Yang Huang; Jet-Chau Wen
      Pages: 68 - 79
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Wenke Wang, Zaiyong Zhang, Tian-chyi Jim Yeh, Gang Qiao, Wenmin Wang, Lei Duan, Shao-Yang Huang, Jet-Chau Wen
      Flow dynamics in a thick vadose zone in an arid region, China was investigated using a field experiment at plots with bare soils and vegetated soils. Detailed pressure head profile along a depth of 8m, groundwater level, soil moisture content at surface, air temperature, and precipitation were observed over one year's time span. The temporal and spatial variations of pressure heads and hydraulic gradients over the time span elucidate the role of air temperature, precipitation, and soil stratification, the growth of vegetation, on the flow dynamics in the vadose zone. The dynamics includes freezing and thawing of surface soils, infiltration, evapotranspiration, distribution of moisture, and groundwater recharge. Estimated hydraulic gradients based on the observed pressure heads suggest that vegetation affected flow dynamics even at 3m below land surface during its growth seasons. The pressure head distributions at the vadose zone over the time span were found correlated well with soil stratification or heterogeneity. Afterward, we estimated the land-atmosphere interface flux, water uptake rate by the plants, and we then discussed the relationship between seasonal variation of temperature, precipitation, evaporation, plant growth, soil stratification (heterogeneity) and the flow dynamics in the vadose zone of the region.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.011
      Issue No: Vol. 106 (2017)
  • Anomalous transport in disordered fracture networks: Spatial Markov model
           for dispersion with variable injection modes
    • Authors: Peter K. Kang; Marco Dentz; Tanguy Le Borgne; Seunghak Lee; Ruben Juanes
      Pages: 80 - 94
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Peter K. Kang, Marco Dentz, Tanguy Le Borgne, Seunghak Lee, Ruben Juanes
      We investigate tracer transport on random discrete fracture networks that are characterized by the statistics of the fracture geometry and hydraulic conductivity. While it is well known that tracer transport through fractured media can be anomalous and particle injection modes can have major impact on dispersion, the incorporation of injection modes into effective transport modeling has remained an open issue. The fundamental reason behind this challenge is that—even if the Eulerian fluid velocity is steady—the Lagrangian velocity distribution experienced by tracer particles evolves with time from its initial distribution, which is dictated by the injection mode, to a stationary velocity distribution. We quantify this evolution by a Markov model for particle velocities that are equidistantly sampled along trajectories. This stochastic approach allows for the systematic incorporation of the initial velocity distribution and quantifies the interplay between velocity distribution and spatial and temporal correlation. The proposed spatial Markov model is characterized by the initial velocity distribution, which is determined by the particle injection mode, the stationary Lagrangian velocity distribution, which is derived from the Eulerian velocity distribution, and the spatial velocity correlation length, which is related to the characteristic fracture length. This effective model leads to a time-domain random walk for the evolution of particle positions and velocities, whose joint distribution follows a Boltzmann equation. Finally, we demonstrate that the proposed model can successfully predict anomalous transport through discrete fracture networks with different levels of heterogeneity and arbitrary tracer injection modes.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.024
      Issue No: Vol. 106 (2017)
  • Quasi-steady state conditions in heterogeneous aquifers during pumping
    • Authors: Yuanyuan Zha; Tian-Chyi J. Yeh; Liangsheng Shi; Shao-Yang Huang; Wenke Wang; Jet-Chau Wen
      Pages: 95 - 110
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Yuanyuan Zha, Tian-Chyi J. Yeh, Liangsheng Shi, Shao-Yang Huang, Wenke Wang, Jet-Chau Wen
      Classical Thiem's well hydraulic theory, other aquifer test analyses, and flow modeling efforts often assume the existence of “quasi-steady” state conditions. That is, while drawdowns due to pumping continue to grow, the hydraulic gradient in the vicinity of the pumping well does not change significantly. These conditions have built upon two-dimensional and equivalent homogeneous conceptual models, but few field data have been available to affirm the existence of these conditions. Moreover, effects of heterogeneity and three-dimensional flow on this quasi-steady state concept have not been thoroughly investigated and discussed before. In this study, we first present a quantitative definition of quasi-steady state (or steady-shape conditions) and steady state conditions based on the analytical solution of two- or three-dimensional flow induced by pumping in unbounded, homogeneous aquifers. Afterward, we use a stochastic analysis to investigate the influence of heterogeneity on the quasi-steady state concept in heterogeneous aquifers. The results of the analysis indicate that the time to reach an approximate quasi-steady state in a heterogeneous aquifer could be quite different from that estimated based on a homogeneous model. We find that heterogeneity of aquifer properties, especially hydraulic conductivity, impedes the development of the quasi-steady state condition before the flow reaching steady state. Finally, 280 drawdown-time data from the hydraulic tomographic survey conducted at a field site corroborate our finding that the quasi-steady state condition likely would not take place in heterogeneous aquifers unless pumping tests last a long period. Research significance (1) Approximate quasi-steady and steady state conditions are defined for two- or three-dimensional flow induced by pumping in unbounded, equivalent homogeneous aquifers. (2) Analysis demonstrates effects of boundary condition, well screen interval, and heterogeneity of parameters on the existence of the quasi-steady, and validity of approximate quasi-steady concept. (3) Temporal evaluation of information content about heterogeneity in head observations are analyzed in heterogeneous aquifer. (4) 280 observed drawdown-time data corroborate the stochastic analysis that quasi-steady is difficult to reach in highly heterogeneous aquifers.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.017
      Issue No: Vol. 106 (2017)
  • Detecting dynamic causal inference in nonlinear two-phase fracture flow
    • Authors: Boris Faybishenko
      Pages: 111 - 120
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Boris Faybishenko
      Identifying dynamic causal inference involved in flow and transport processes in complex fractured-porous media is generally a challenging task, because nonlinear and chaotic variables may be positively coupled or correlated for some periods of time, but can then become spontaneously decoupled or non-correlated. In his 2002 paper (Faybishenko, 2002), the author performed a nonlinear dynamical and chaotic analysis of time-series data obtained from the fracture flow experiment conducted by Persoff and Pruess (1995), and, based on the visual examination of time series data, hypothesized that the observed pressure oscillations at both inlet and outlet edges of the fracture result from a superposition of both forward and return waves of pressure propagation through the fracture. In the current paper, the author explores an application of a combination of methods for detecting nonlinear chaotic dynamics behavior along with the multivariate Granger Causality (G-causality) time series test. Based on the G-causality test, the author infers that his hypothesisis correct, and presents a causation loop diagram of the spatial-temporal distribution of gas, liquid, and capillary pressures measured at the inlet and outlet of the fracture. The causal modeling approach can be used for the analysis of other hydrological processes, for example, infiltration and pumping tests in heterogeneous subsurface media, and climatic processes, for example, to find correlations between various meteorological parameters, such as temperature, solar radiation, barometric pressure, etc.
      Graphical abstract image

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.02.011
      Issue No: Vol. 106 (2017)
  • Poroelastic theory of consolidation in unsaturated soils incorporating
           gravitational body forces
    • Authors: Wei-Cheng Lo; Nan-Chieh Chao; Chu-Hui Chen; Jhe-Wei Lee
      Pages: 121 - 131
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): Wei-Cheng Lo, Nan-Chieh Chao, Chu-Hui Chen, Jhe-Wei Lee
      The generalization of the poroelasticity theory of consolidation in unsaturated soils to well represent gravitational body forces is presented in the current study. Three partial differential equations featuring the displacement vector of the solid phase, along with the excess pore water and air pressures as dependent variables are derived, with coupling that occurs in the first-order temporal- and spatial- derivative terms. The former arises from viscous drag between solid and fluid, whereas the latter is attributed to the presence of gravity. Given the physically-consistent initial and boundary conditions, these coupled equations are numerically solved under uniaxial strain as a representative example. Our results reveal that variations in the excess pore water pressure due to the existence of gravitational forces increase with soil depth, but these variations are not significant if the soil layer is not sufficiently long. A dimensionless parameter is defined theoretically to quantify the impact of those forces on the final total settlement. This impact is shown to become greater as the soil layer is less stiff and has more length, and bears an inversely-proportional trend with initial water saturation.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.03.006
      Issue No: Vol. 106 (2017)
  • Wave propagation in double-porosity dual-permeability materials: Velocity
           and attenuation
    • Authors: M.D. Sharma
      Pages: 132 - 143
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): M.D. Sharma
      This study considers the propagation of harmonic plane waves in a double-porosity solid saturated by a viscous fluid. Two different porosities are supported with different permeabilities to facilitate the wave-induced fluid-flow in this composite material. The variation of the fluid content in the pores due to the wave-induced flow is expressed in terms of the dilatation of constituent particles in the porous aggregate. This fluid-flow can be considered through the constitutive relations with modified anelastic coefficients. The modified coefficients, being frequency dependent and complex, illustrate the dispersive and anelastic behaviour of double-porosity dual-permeability materials. Relevant equations of motion are solved to explain the propagation of three longitudinal waves and one transverse wave in double-porosity dual-permeability medium. A numerical example is considered to illustrate dispersion in velocity and attenuation of the four waves. Effect of wave-induced fluid-flow is analysed with changes in wave-inhomogeneity, pore-fluid viscosity and double-porosity structure.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.02.016
      Issue No: Vol. 106 (2017)
  • Modeling the release of Escherichia coli from soil into overland flow
           under raindrop impact
    • Authors: C. Wang; J.-Y. Parlange; E.W. Rasmussen; X. Wang; M. Chen; H.E. Dahlke; M.T. Walter
      Pages: 144 - 153
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): C. Wang, J.-Y. Parlange, E.W. Rasmussen, X. Wang, M. Chen, H.E. Dahlke, M.T. Walter
      Pathogen transport through the environment is complicated, involving a variety of physical, chemical, and biological processes. This study considered the transfer of microorganisms from soil into overland flow under rain-splash conditions. Although microorganisms are colloidal particles, they are commonly quantified as colony-forming units (CFUs) per volume rather than as a mass or number of particles per volume, which poses a modeling challenge. However, for very small particles that essentially remain suspended after being ejected into ponded water and for which diffusion can be neglected, the Gao model, originally derived for solute transfer from soil, describes particle transfer into suspension and is identical to the Hairsine–Rose particle erosion model for this special application. Small-scale rainfall experiments were conducted in which an Escherichia coli (E. coli) suspension was mixed with a simple soil (9:1 sand-to-clay mass ratio). The model fit the experimental E. coli data. Although re-conceptualizing the Gao solute model as a particle suspension model was convenient for accommodating the unfortunate units of CFU ml−1, the Hairsine–Rose model is insensitive to assumptions about E. coli per CFU as long as the assumed initial mass concentration of E. coli is very small compared to that of the soil particle classes. Although they undoubtedly actively interact with their environment, this study shows that transport of microorganisms from soil into overland storm flows can be reasonably modeled using the same principles that have been applied to small mineral particles in previous studies.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2016.10.016
      Issue No: Vol. 106 (2017)
  • Effects of trees on mean wind, turbulence and momentum exchange within and
           above a real urban environment
    • Authors: M.G. Giometto; A. Christen; P.E. Egli; M.F. Schmid; R.T. Tooke; N.C. Coops; M.B. Parlange
      Pages: 154 - 168
      Abstract: Publication date: August 2017
      Source:Advances in Water Resources, Volume 106
      Author(s): M.G. Giometto, A. Christen, P.E. Egli, M.F. Schmid, R.T. Tooke, N.C. Coops, M.B. Parlange
      Large-eddy simulations (LES) are used to gain insight into the effects of trees on turbulence, aerodynamic parameters, and momentum transfer rates characterizing the atmosphere within and above a real urban canopy. Several areas are considered that are part of a neighborhood in the city of Vancouver, BC, Canada where a small fraction of trees are taller than buildings. In this area, eight years of continuous wind and turbulence measurements are available from a 30 m meteorological tower. Data from airborne light detection and ranging (LiDAR) are used to represent both buildings and vegetation at the LES resolution. In the LES algorithm, buildings are accounted through an immersed boundary method, whereas vegetation is parameterized via a location-specific leaf area density. LES are performed including and excluding vegetation from the considered urban areas, varying wind direction and leaf area density. Surface roughness lengths (z 0) from both LES and tower measurements are sensitive to the 0 ≤ LAI / λ f b < 3 parameter, where LAI is the leaf area index and λ f b is the frontal area fraction of buildings characterizing a given canopy. For instance, tower measurements predict a 19% seasonal increase in z 0, slightly lower than the 27% increase featured by LES for the most representative canopy (leaves-off LAI / λ f b = 0.74 , leaves-on LAI / λ f b = 2.24 ). Removing vegetation from such a canopy would cause a dramatic drop of approximately 50% in z 0 when compared to the reference summer value. The momentum displacement height (d) from LES also consistently increases as LAI / λ f b increases, due in large part to the disproportionate amount of drag that the (few) relatively taller trees exert on the flow. LES and measurements both predict an increase in the ratio of turbulent to mean kinetic energy (TKE/MKE) at the tower sampling height going from winter to summer, and LES also show how including vegetation results in a more (positive) negatively skewed (horizontal) vertical velocity distribution – reflecting a more intermittent velocity field which favors sweep motions when compared to ejections. Within the urban canopy, the effects of trees are twofold: on one hand, they act as a direct momentum sink for the mean flow; on the other, they reduce downward turbulent transport of high-momentum fluid, significantly reducing the wind intensity at the heights where people live and buildings consume energy.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.06.018
      Issue No: Vol. 106 (2017)
  • Estimation of sub-core permeability statistical properties from
           coreflooding data
    • Authors: Avinoam Rabinovich
      Abstract: Publication date: Available online 26 July 2017
      Source:Advances in Water Resources
      Author(s): Avinoam Rabinovich
      Knowledge of sub-core permeability is necessary for accurate numerical modeling of coreflooding experiments and for investigation of sub-core flow phenomenon. A new method for estimating sub-core permeability geometric mean (kG ) and log-permeability variance ( σ y 2 ) is presented. The method is based on matching coreflooding experiment measurements of wetting phase relative permeability with semi-analytical calculations of effective relative permeability. The semi-analytical solution is formulated assuming log-normal permeability (k), steady state and capillary-limit conditions. It is based on the geometric mean and log-phase-permeability variance for isotropic k and power law averaging for anisotropic correlations. The solution is validated on synthetic k realizations by comparison with numerical calculations. Then, the estimation method is tested on synthetic data assuming various types of core capillary pressure relationships, relative permeability functions and k anisotropies. Results demonstrate high accuracy in almost all of the cases except for small anisotropy ratios lh /lv between horizontal (lh ) and vertical (lv ) dimensionless correlation lengths, where flow is in the horizontal direction, and when σ y 2 is large. The method is also validated using data from CO2-brine coreflooding experiments conducted on two different cores. It is found that the estimation method remains accurate in these realistic settings, however, accuracy of kG is reduced when the core permeability departs from a log-normal distribution.

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.07.012
  • Identifying three-dimensional nested groundwater flow systems in a
           Tóthian basin
    • Authors: Xu-Sheng Wang; Li Wan; Xiao-Wei Jiang; Hailong Li; Yangxiao Zhou; Junzhi Wang; Xiaohui Ji
      Abstract: Publication date: Available online 25 July 2017
      Source:Advances in Water Resources
      Author(s): Xu-Sheng Wang, Li Wan, Xiao-Wei Jiang, Hailong Li, Yangxiao Zhou, Junzhi Wang, Xiaohui Ji
      Nested groundwater flow systems have been revealed in Tóth's theory as the structural property of basin-scale groundwater circulation but were only well known with two-dimensional (2D) profile models. The method of searching special streamlines across stagnation points for partitioning flow systems, which has been successfully applied in the 2D models, has never been implemented for three-dimensional (3D) Tóthian basins because of the difficulty in solving the dual stream functions. Alternatively, a new method is developed to investigate 3D nested groundwater flow systems without determination of stagnation points. Connective indices are defined to quantify the connection between individual recharge and discharge zones along streamlines. Groundwater circulation cells (GWCCs) are identified according to the distribution of the connective indices and then grouped into local, intermediate and regional flow systems. This method requires existing solution of the flow velocity vector and is implemented via particle tracking technique. It is applied in a hypothetical 3D Tóthian basin with an analytical solution of the flow field and in a real-world basin with a numerical modeling approach. Different spatial patterns of flow systems compared to 2D profile models are found. The outcrops boundaries of GWCCs on water table may significantly deviate from and are not parallel to the nearby water table divides. Topological network is proposed to represent the linked recharge-discharge zones through closed and open GWCCs. Sensitivity analysis indicates that the development of GWCCs depends on the basin geometry, hydraulic parameters and water table shape.
      Graphical abstract image

      PubDate: 2017-07-27T17:49:23Z
      DOI: 10.1016/j.advwatres.2017.07.016
  • Pore-scale modeling of capillary trapping in water-wet porous media: A new
           cooperative pore-body filling model
    • Authors: L.C. Ruspini; R. Farokhpoor; P.E. Øren
      Abstract: Publication date: Available online 13 July 2017
      Source:Advances in Water Resources
      Author(s): L.C. Ruspini, R. Farokhpoor, P.E. Øren
      We present a pore-network model study of capillary trapping in water-wet porous media. The amount and distribution of trapped non-wetting phase is determined by the competition between two trapping mechanisms - snap-off and cooperative pore-body filling. We develop a new model to describe the pore-body filling mechanism in geologically realistic pore-networks. The model accounts for the geometrical characteristics of the pore, the spatial location of the connecting throats and the local fluid topology at the time of the displacement. We validate the model by comparing computed capillary trapping curves with published data for four different water-wet rocks. Computations are performed on pore-networks extracted from micro-CT images and process-based reconstructions of the actual rocks used in the experiments. Compared with commonly used stochastic models, the new model describes more accurately the experimental measurements, especially for well connected porous systems where trapping is controlled by subtleties of the pore structure. The new model successfully predicts relative permeabilities and residual saturation for Bentheimer sandstone using in-situ measured contact angles as input to the simulations. The simulated trapped cluster size distributions are compared with predictions from percolation theory.

      PubDate: 2017-07-20T17:39:18Z
      DOI: 10.1016/j.advwatres.2017.07.008
  • Assessing sequential data assimilation techniques for integrating GRACE
           data into a hydrological model
    • Authors: M. Khaki; I. Hoteit; M. Kuhn; J. Awange; E. Forootan; A. van Dijk; M. Schumacher; C. Pattiaratchi
      Abstract: Publication date: Available online 6 July 2017
      Source:Advances in Water Resources
      Author(s): M. Khaki, I. Hoteit, M. Kuhn, J. Awange, E. Forootan, A. van Dijk, M. Schumacher, C. Pattiaratchi
      The time-variable terrestrial water storage (TWS) products from the Gravity Recovery And Climate Experiment (GRACE) have been increasingly used in recent years to improve the simulation of hydrological models by applying data assimilation techniques. In this study, for the first time, we assess the performance of the most popular data assimilation sequential techniques for integrating GRACE TWS into the World-Wide Water Resources Assessment (W3RA) model. We implement and test stochastic and deterministic ensemble-based Kalman filters (EnKF), as well as Particle filters (PF) using two different resampling approaches of Multinomial Resampling and Systematic Resampling. These choices provide various opportunities for weighting observations and model simulations during the assimilation and also accounting for error distributions. Particularly, the deterministic EnKF is tested to avoid perturbing observations before assimilation (that is the case in an ordinary EnKF). Gaussian-based random updates in the EnKF approaches likely do not fully represent the statistical properties of the model simulations and TWS observations. Therefore, the fully non-Gaussian PF is also applied to estimate more realistic updates. Monthly GRACE TWS are assimilated into W3RA covering the entire Australia. To evaluate the filters performances and analyze their impact on model simulations, their estimates are validated by independent in-situ measurements. Our results indicate that all implemented filters improve the estimation of water storage simulations of W3RA. The best results are obtained using two versions of deterministic EnKF, i.e. the Square Root Analysis (SQRA) scheme and the Ensemble Square Root Filter (EnSRF), respectively improving the model groundwater estimations errors by 34% and 31% compared to a model run without assimilation. Applying the PF along with Systematic Resampling successfully decreases the model estimation error by 23%.

      PubDate: 2017-07-08T03:00:22Z
      DOI: 10.1016/j.advwatres.2017.07.001
  • Formation factor in Bentheimer and Fontainebleau sandstones: Theory
           compared with pore-scale numerical simulations
    • Authors: Behzad Ghanbarian; Carl F. Berg
      Abstract: Publication date: Available online 19 June 2017
      Source:Advances in Water Resources
      Author(s): Behzad Ghanbarian, Carl F. Berg
      Accurate quantification of formation resistivity factor F (also called formation factor) provides useful insight into connectivity and pore space topology in fully saturated porous media. In particular the formation factor has been extensively used to estimate permeability in reservoir rocks. One of the widely applied models to estimate F is Archie's law (F =φ − m in which φ is total porosity and m is cementation exponent) that is known to be valid in rocks with negligible clay content, such as clean sandstones. In this study we compare formation factors determined by percolation and effective-medium theories as well as Archie's law with numerical simulations of electrical resistivity on digital rock models. These digital models represent Bentheimer and Fontainebleau sandstones and are derived either by reconstruction or directly from micro-tomographic images. Results show that the universal quadratic power law from percolation theory accurately estimates the calculated formation factor values in network models over the entire range of porosity. However, it crosses over to the linear scaling from the effective-medium approximation at the porosity of 0.75 in grid models. We also show that the effect of critical porosity, disregarded in Archie's law, is nontrivial, and the Archie model inaccurately estimates the formation factor in low-porosity homogeneous sandstones.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.016
  • A General Mixture Model for Sediment Laden Flows
    • Authors: Lixin Liang; Xiping Yu; Fabián Bombardelli
      Abstract: Publication date: Available online 17 June 2017
      Source:Advances in Water Resources
      Author(s): Lixin Liang, Xiping Yu, Fabián Bombardelli
      A mixture model for general description of sediment-laden flows is developed based on an Eulerian-Eulerian two-phase flow theory, with the aim at gaining computational speed in the prediction, but preserving the accuracy of the complete two-fluid model. The basic equations of the model include the mass and momentum conservation equations for the sediment-water mixture, and the mass conservation equation for sediment. However, a newly-obtained expression for the slip velocity between phases allows for the computation of the sediment motion, without the need of solving the momentum equation for sediment. The turbulent motion is represented for both the fluid and the particulate phases. A modified k-ε model is used to describe the fluid turbulence while an algebraic model is adopted for turbulent motion of particles. A two-dimensional finite difference method based on the SMAC scheme was used to numerically solve the mathematical model. The model is validated through simulations of fluid and suspended sediment motion in steady open-channel flows, both in equilibrium and non-equilibrium states, as well as in oscillatory flows. The computed sediment concentrations, horizontal velocity and turbulent kinetic energy of the mixture are all shown to be in good agreement with available experimental data, and importantly, this is done at a fraction of the computational efforts required by the complete two-fluid model.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.012
  • Sampling design optimisation for rainfall prediction using a
           non-stationary geostatistical model
    • Authors: Alexandre M.J-C. Wadoux; Dick J. Brus; Miguel A. Rico-Ramirez; Gerard B.M. Heuvelink
      Abstract: Publication date: Available online 16 June 2017
      Source:Advances in Water Resources
      Author(s): Alexandre M.J-C. Wadoux, Dick J. Brus, Miguel A. Rico-Ramirez, Gerard B.M. Heuvelink
      The accuracy of spatial predictions of rainfall by merging rain-gauge and radar data is partly determined by the sampling design of the rain-gauge network. Optimising the locations of the rain-gauges may increase the accuracy of the predictions. Existing spatial sampling design optimisation methods are based on minimisation of the spatially averaged prediction error variance under the assumption of intrinsic stationarity. Over the past years, substantial progress has been made to deal with non-stationary spatial processes in kriging. Various well-documented geostatistical models relax the assumption of stationarity in the mean, while recent studies show the importance of considering non-stationarity in the variance for environmental processes occurring in complex landscapes. We optimised the sampling locations of rain-gauges using an extension of the Kriging with External Drift (KED) model for prediction of rainfall fields. The model incorporates both non-stationarity in the mean and in the variance, which are modelled as functions of external covariates such as radar imagery, distance to radar station and radar beam blockage. Spatial predictions are made repeatedly over time, each time recalibrating the model. The space-time averaged KED variance was minimised by Spatial Simulated Annealing (SSA). The methodology was tested using a case study predicting daily rainfall in the north of England for a one-year period. Results show that (i) the proposed non-stationary variance model outperforms the stationary variance model, and (ii) a small but significant decrease of the rainfall prediction error variance is obtained with the optimised rain-gauge network. In particular, it pays off to place rain-gauges at locations where the radar imagery is inaccurate, while keeping the distribution over the study area sufficiently uniform.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.005
  • A data driven model for the impact of IFT and density variations on CO2
           storage capacity in geologic formations
    • Authors: Mohammad A. Nomeli; Amir Riaz
      Abstract: Publication date: Available online 16 June 2017
      Source:Advances in Water Resources
      Author(s): Mohammad A. Nomeli, Amir Riaz
      Carbon dioxide (CO2) storage in depleted hydrocarbon reservoirs and deep saline aquifers is one of the most promising solutions for decreasing CO2 concentration in the atmosphere. One of the important issues for CO2 storage in subsurface environments is the sealing efficiency of low-permeable cap-rocks overlying potential CO2 storage reservoirs. Though we focus on the effect of IFT in this study as a factor influencing sealing efficiency or storage capacity, other factors such as interfacial interactions, wettability, pore radius and interfacial mass transfer also affect the mobility and storage capacity of CO2 phase in the pore space. The study of the variation of IFT is however important because the pressure needed to penetrate a pore depends on both the pore size and the interfacial tension. Hence small variations in IFT can affect flow across a large population of pores. A novel model is proposed to find the IFT of the ternary systems (CO2/brine-salt) in a range of temperatures (300-373 K), pressures (50-250 bar), and up to 6 molal salinity applicable to CO2 storage in geological formations through a multi-variant non-linear regression of experimental data. The method uses a general empirical model for the quaternary system CO2/brine-salts that can be made to coincide with experimental data for a variety of solutions. We introduce correction parameters into the model, which compensates for uncertainties, and enforce agreement with experimental data. The results for IFT show a strong dependence on temperature, pressure, and salinity. The model has been found to describe the experimental data in the appropriate parameter space with reasonable precision. Finally, we use the new model to evaluate the effects of formation depth on the actual efficiency of CO2 storage. The results indicate that, in the case of CO2 storage in deep subsurface environments as a global-warming mitigation strategy, CO2 storage capacity increases with reservoir depth.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.015
  • Catchment tomography - An approach for spatial parameter estimation
    • Authors: D. Baatz; W. Kurtz; H.-J. Hendricks Franssen; H. Vereecken; S.J. Kollet
      Abstract: Publication date: Available online 16 June 2017
      Source:Advances in Water Resources
      Author(s): D. Baatz, W. Kurtz, H.-J. Hendricks Franssen, H. Vereecken, S.J. Kollet
      The use of distributed-physically based hydrological models is often hampered by the lack of information on key parameters and their spatial distribution and temporal dynamics. Typically, the estimation of parameter values is impeded by the lack of sufficient observations leading to mathematically underdetermined estimation problems and thus non-uniqueness. Catchment tomography (CT) presents a method to estimate spatially distributed model parameters by resolving the integrated signal of stream runoff in response to precipitation. Basically CT exploits the information content generated by a distributed precipitation signal both in time and space. In a moving transmitter-receiver concept, high resolution, radar based precipitation data are applied with a distributed surface runoff model. Synthetic stream water level observations, serving as receivers, are assimilated with an Ensemble Kalman Filter. With a joint state-parameter update the spatially distributed Manning's roughness coefficient, n, is estimated using the coupled Terrestrial Systems Modelling Platform and the Parallel Data Assimilation Framework (TerrSysMP-PDAF). The sequential data assimilation in combination with the distributed precipitation continuously integrates new information into the model, thus, increasingly constraining the parameter space. With this large amount of data included for the parameter estimation, CT reduces the problem of underdetermined model parameters. The initially biased Manning's coefficients spatially distributed in two and four fixed parameter zones are estimated with errors of less than 3% and 17%, respectively, with only 64 model realizations. It is shown that the distributed precipitation is of major importance for this approach.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.006
  • ISPH modelling of landslide generated waves for rigid and deformable
           slides in Newtonian and Non-Newtonian reservoir fluids
    • Authors: Shahab Yeylaghi; Belaid Moa; Bradley Buckham; Peter Oshkai; Jose Vasquez; Curran Crawford
      Abstract: Publication date: Available online 16 June 2017
      Source:Advances in Water Resources
      Author(s): Shahab Yeylaghi, Belaid Moa, Bradley Buckham, Peter Oshkai, Jose Vasquez, Curran Crawford
      A comprehensive modeling of landslide generated waves using an in-house parallel Incompressible Smoothed Particle Hydrodynamics (ISPH) code is presented in this paper. The study of landslide generated waves is challenging due to the involvement of several complex physical phenomena, such as slide-water interaction, turbulence and complex free surface profiles. A numerical tool that can efficiently calculate both slide motion, impact with the surface and the resulting wave is needed for ongoing study of these phenomena. Mesh-less numerical methods, such as Smoothed Particle Hydrodynamics (SPH), handle the slide motion and the complex free surface profile with ease. In this paper, an in-house parallel explicit ISPH code is used to simulate both subaerial and submarine landslides in 2D and in more realistic 3D applications. Both rigid and deformable slides are used to generate the impulsive waves. A landslide case is simulated where a slide falls into a non-Newtonian reservoir fluid (water-bentonite mixture). A new technique is also proposed to calculate the motion of a rigid slide on an inclined ramp implicitly, without using the prescribed motion in SPH. For all the test cases, results generated from the proposed ISPH method compared with available experimental data show good agreement.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.013
  • Nano-scale Experimental Investigation of In-situ Wettability and
           Spontaneous Imbibition in Ultra-tight Reservoir Rocks
    • Authors: Morteza Akbarabadi; Soheil Saraji; Mohammad Piri; Dan Georgi; Mohammad Delshad
      Abstract: Publication date: Available online 15 June 2017
      Source:Advances in Water Resources
      Author(s): Morteza Akbarabadi, Soheil Saraji, Mohammad Piri, Dan Georgi, Mohammad Delshad
      We investigated spontaneous imbibition behavior, three-dimensional fluid occupancy maps, and in-situ wettability at the nano scale in five ultra-tight and shale reservoir rock samples. For this purpose, we developed a novel technique by integrating a custom-built in-situ miniature fluid-injection module with a non-destructive high-resolution X-ray imaging system. Small cylindrical core samples (15-60 μm in diameter) were prepared from reservoir rocks using Focused-Ion Beam (FIB) milling technique. The pore network inside the samples were first characterized using ultra-high resolution three-dimensional images obtained at initial state by X-ray nano-tomography (Nano-CT) and FIB-Scanning Electron Microscopy (FIB-SEM) techniques at the nano scale. The petrophysical parameters, including porosity, permeability, pore-size distribution, and organic content were computed for each sample using image analysis. We then performed series of imbibition experiments using brine, oil, and surfactant solutions on each core sample. We observed that both oil and brine phases spontaneously imbibe into the pore network of the rock samples at various quantities. We also, for the first time, examined fluid distribution in individual pores and found a complex wettability behavior at the pore scale in the reservoir rock samples. Three pore types were identified with water-wet, oil-wet, and fractionally-wet behaviors. This work opens a new path to developing an improved understanding of the pore-level physics involved in multi-phase flow and transport not only in tight rock samples but also in other nanoporous material used in different science and engineering applications.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.004
  • Consistency and bicharacteristic analysis of integral porosity shallow
           water models. Explaining model oversensitivity to mesh design
    • Authors: Vincent Guinot
      Abstract: Publication date: Available online 15 June 2017
      Source:Advances in Water Resources
      Author(s): Vincent Guinot
      The Integral Porosity and Dual Integral Porosity two-dimensional shallow water models have been proposed recently as efficient upscaled models for urban floods. Very little is known so far about their consistency and wave propagation properties. Simple numerical experiments show that both models are unusually sensitive to the computational grid. In the present paper, a two-dimensional consistency and characteristic analysis is carried out for these two models. The following results are obtained: (i) the models are almost insensitive to grid design when the porosity is isotropic, (ii) anisotropic porosity fields induce an artificial polarization of the mass/momentum fluxes along preferential directions when triangular meshes are used and (iii) extra first-order derivatives appear in the governing equations when regular, quadrangular cells are used. The hyperbolic system is thus mesh-dependent, and with it the wave propagation properties of the model solutions. Criteria are derived to make the solution less mesh-dependent, but it is not certain that these criteria can be satisfied at all computational points when real-world situations are dealt with.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.008
  • Fracture flow due to hydrothermally induced quartz growth
    • Authors: Tobias Kling; Jens-Oliver Schwarz; Frank Wendler; Frieder Enzmann; Philipp Blum
      Abstract: Publication date: Available online 15 June 2017
      Source:Advances in Water Resources
      Author(s): Tobias Kling, Jens-Oliver Schwarz, Frank Wendler, Frieder Enzmann, Philipp Blum
      Mineral precipitations are a common feature and limitation of initially open, permeable rock fractures by forming sealing structures or secondary roughness in open voids. Hence, the objective of this numerical study is the evaluation of hydraulic properties of fractures sealed by hydrothermally induced needle and compact quartz growth. Phase-field models of progressive syntaxial and idiomorphic quartz growth are implemented into a fluid flow simulation solving the Navier-Stokes equation. Flow simulations for both quartz types indicate an obvious correlation between changes in permeability, fracture properties (e.g. aperture, relative roughness and porosity) and crystal growth behavior, which also forms distinct flow paths. Thus, at lower sealing stages initial fracture permeability significantly drops down for the ‘needle fracture’ forming highly tortuous flow paths, while the ‘compact fracture’ records a considerably smaller loss. Fluid flow in both sealing fractures most widely is governed by a “parallel plate”-like cubic law behavior. However, the ‘needle fracture’ also reveals flow characteristics of a porous media. A semi-theoretical equation is introduced that links geometrical (am) with hydraulically effective apertures (ah) and the relative fracture roughness. For this purpose, a geometry factor α is introduced being α=2.5 for needle quartz and α=1.0 for compact quartz growth. In contrast to most common ah-am-relationships this novel formulation not only reveals more precise predictions for the needle (RMSE=1.5) and the compact fractures (RMSE=3.2), but also exhibit a larger range of validity concerning the roughness of the ‘needle’ (σ/am =0 to 2.4) and the ‘compact fractures’ (σ/am =0 to 1.8).

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.011
  • An immersed boundary-lattice Boltzmann model for biofilm growth in porous
    • Authors: M. Benioug; F. Golfier; C. Oltean; M.A. Buès; T. Bahar; J. Cuny
      Abstract: Publication date: Available online 15 June 2017
      Source:Advances in Water Resources
      Author(s): M. Benioug, F. Golfier, C. Oltean, M.A. Buès, T. Bahar, J. Cuny
      In this paper, we present a two-dimensional pore-scale numerical model to investigate the main mechanisms governing biofilm growth in porous media. The fluid flow and solute transport equations are coupled with a biofilm evolution model. Fluid flow is simulated with an immersed boundary–lattice Boltzmann model while solute transport is described with a volume-of-fluid-type approach. A cellular automaton algorithm combined with immersed boundary methods was developed to describe the spreading and distribution of biomass. Bacterial attachment and detachment mechanisms are also taken into account. The capability of this model to describe correctly the couplings involved between fluid circulation, nutrient transport and bacterial growth is tested under different hydrostatic and hydrodynamic conditions (i) on a flat medium and (ii) for a complex porous medium. For the second case, different regimes of biofilm growth are identified and are found to be related to the dimensionless parameters of the model, Damköhler and Péclet numbers and dimensionless shear stress. Finally, the impact of biofilm growth on the macroscopic properties of the porous medium is investigated and we discuss the unicity of the relationships between hydraulic conductivity and biofilm volume fraction.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.009
  • Temporal asymmetry in precipitation time series and its influence on flow
           simulations in combined sewer systems
    • Authors: Thomas Müller; Manfred Schütze; András Bárdossy
      Abstract: Publication date: Available online 14 June 2017
      Source:Advances in Water Resources
      Author(s): Thomas Müller, Manfred Schütze, András Bárdossy
      A property of natural processes is temporal irreversibility. However, this property cannot be reflected by most statistics used to describe precipitation time series and, consequently, is not considered in most precipitation models. In this paper, a new statistic, the asymmetry measure, is introduced and applied to precipitation enabling to detect and quantify irreversibility. It is used to analyze two different data sets of Singapore and Germany. The data of both locations show a significant asymmetry for high temporal resolutions. The asymmetry is more pronounced for Singapore where the climate is dominated by convective precipitation events. The impact of irreversibility on applications is analyzed on two different hydrological sewer system models. The results show that the effect of the irreversibility can lead to biases in combined sewer overflow statistics. This bias is in the same order as the effect that can be achieved by real time control of sewer systems. Consequently, wrong conclusion can be drawn if synthetic time series are used for sewer systems if asymmetry is present, but not considered in precipitation modeling.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.010
  • Statistical Representative Elementary Volumes of Porous Media determined
           using Greyscale Analysis of 3D Tomograms
    • Authors: S. Bruns; S.L.S. Stipp; H.O. Sørensen
      Abstract: Publication date: Available online 13 June 2017
      Source:Advances in Water Resources
      Author(s): S. Bruns, S.L.S. Stipp, H.O. Sørensen
      Digital rock physics carries the dogmatic concept of having to segment volume images for quantitative analysis but segmentation rejects huge amounts of signal information. Information that is essential for the analysis of difficult and marginally resolved samples, such as materials with very small features, is lost during segmentation. In X-ray nanotomography reconstructions of Hod chalk we observed partial volume voxels with an abundance that limits segmentation based analysis. Therefore, we investigated the suitability of greyscale analysis for establishing statistical representative elementary volumes (sREV) for the important petrophysical parameters of this type of chalk, namely porosity, specific surface area and diffusive tortuosity, by using volume images without segmenting the datasets. Instead, grey level intensities were transformed to a voxel level porosity estimate using a Gaussian mixture model. A simple model assumption was made that allowed formulating a two point correlation function for surface area estimates using Bayes’ theory. The same assumption enables random walk simulations in the presence of severe partial volume effects. The established sREVs illustrate that in compacted chalk, these simulations cannot be performed in binary representations without increasing the resolution of the imaging system to a point where the spatial restrictions of the represented sample volume render the precision of the measurement unacceptable. We illustrate this by analyzing the origins of variance in the quantitative analysis of volume images, i.e. resolution dependence and intersample and intrasample variance. Although we cannot make any claims on the accuracy of the approach, eliminating the segmentation step from the analysis enables comparative studies with higher precision and repeatability.

      PubDate: 2017-06-15T01:22:12Z
      DOI: 10.1016/j.advwatres.2017.06.002
  • Modeling of flow and mixing in 3D rough-walled rock fracture intersections
    • Authors: Liangchao Zou; Lanru Jing; Vladimir Cvetkovic
      Abstract: Publication date: Available online 13 June 2017
      Source:Advances in Water Resources
      Author(s): Liangchao Zou, Lanru Jing, Vladimir Cvetkovic
      The processes of fluid flow and solute transport through rock fractures are of primary importance in environmental engineering and geosciences. This study presented numerical modeling results of fluid flow and solute transport in a 3D rock fracture-matrix system with an orthogonal intersection of two rough-walled rock fractures. The rough-walled fracture geometry models were built from laser-scanned data of a real rock surface, for a realistic representation of natural rock fracture surface roughness. The fluid flow in the two intersected fractures and solute transport in the fracture-matrix system were simulated by solving the Navier-Stokes equations (NSE) and transport equation in the entire system. The dependence of mixing on Péclet number (Pe) and flow directionality features was analyzed. The results directly visualized important channeling flow patterns that significantly enhanced the solute mixing process at the rough-walled fracture intersection. The illustrated channeling flow and associated impacts on mixing are particularly important in the prediction of solute transport in natural fractured rocks, especially when discrete fracture network (DFN) approach is applied.

      PubDate: 2017-06-15T01:22:12Z
      DOI: 10.1016/j.advwatres.2017.06.003
  • Role of corner interfacial area in uniqueness of capillary
    • Authors: Omar E. Godinez-Brizuela; Nikolaos K. Karadimitriou; Vahid Joekar-Niasar; C.A. Shore; Mart Oostrom
      Abstract: Publication date: Available online 13 June 2017
      Source:Advances in Water Resources
      Author(s): Omar E. Godinez-Brizuela, Nikolaos K. Karadimitriou, Vahid Joekar-Niasar, C.A. Shore, Mart Oostrom
      Capillary pressure (Pc ) and phase saturation (Sw ) in two-phase flow are well known to be hysteretically related. Thermodynamically-derived multiphase flow theories conjecture that this hysteresis will be lifted if specific interfacial area (anw ) is included as a new state variable to create a unique Pc - S - anw surface. Specific interfacial area is defined as the total interfacial area per volume of a porous medium. Several studies have confirmed the existence of a unique Pc - Sw - anw surface under equilibrium conditions for a given porous medium. However, there is only one experimental work in the literature, where the uniqueness of this surface under transient conditions was questioned. However, in the data analysis only the terminal menisci were considered to calculate the specific interfacial area. In this paper, we investigate the uniqueness of Pc - S - anw surfaces with and without the inclusion of corner fluid-fluid interfacial area, under different dynamic conditions, in two different micro-models bearing two different pore morphologies (granular vs. triangulated). We establish a systematic metric to analyze hysteresis under different hydrodynamic conditions.

      PubDate: 2017-06-15T01:22:12Z
      DOI: 10.1016/j.advwatres.2017.06.007
  • Capillary pressure-saturation relationships for porous granular materials:
           pore morphology method vs. pore unit assembly method
    • Authors: Thomas Sweijen; Hamed Aslannejad; S. Majid Hassanizadeh
      Abstract: Publication date: Available online 6 June 2017
      Source:Advances in Water Resources
      Author(s): Thomas Sweijen, Hamed Aslannejad, S. Majid Hassanizadeh
      In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe- Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

      PubDate: 2017-06-10T06:09:32Z
      DOI: 10.1016/j.advwatres.2017.06.001
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