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Showing 1 - 200 of 3042 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 19, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 16, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 81, 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: 326, 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  
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: 203, 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: 22, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 5, 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)
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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: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 124, 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: 24, 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: 21, 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: 8, 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: 39, 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: 44, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
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: 12)
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: 20, 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: 24)
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: 34, 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: 4)
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: 5, 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: 21, 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: 58)
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: 339, 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: 6, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 29, 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: 311, 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: 4, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 7, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 398, 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: 50, 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: 5)
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: 5, 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: 6, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 46, 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: 46, 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: 34, 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: 15, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 30, 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: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 44, 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: 182, 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: 2)
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: 23, 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: 33, 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: 52, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 4)
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: 161, 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: 10)
Anesthésie & Réanimation     Full-text available via subscription  
Anesthesiology Clinics     Full-text available via subscription   (Followers: 21, 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: 153, 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   (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  [3042 journals]
  • Multiscale modelling of dual-porosity porous media; a computational
           pore-scale study for flow and solute transport
    • Authors: Enno T. de Vries; Amir Raoof; Martinus Th. van Genuchten
      Pages: 82 - 95
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): Enno T. de Vries, Amir Raoof, Martinus Th. van Genuchten
      Many environmental and agricultural applications involve the transport of water and dissolved constituents through aggregated soil profiles, or porous media that are structured, fractured or macroporous in other ways. During the past several decades, various process-based macroscopic models have been used to simulate contaminant transport in such media. Many of these models consider advective-dispersive transport through relatively large inter-aggregate pore domains, while exchange with the smaller intra-aggregate pores is assumed to be controlled by diffusion. Exchange of solute between the two domains is often represented using a first-order mass transfer coefficient, which is commonly obtained by fitting to observed data. This study aims to understand and quantify the solute exchange term by applying a dual-porosity pore-scale network model to relatively large domains, and analysing the pore-scale results in terms of the classical dual-porosity (mobile-immobile) transport formulation. We examined the effects of key parameters (notably aggregate porosity and aggregate permeability) on the main dual-porosity model parameters, i.e., the mobile water fraction (ϕm ) and the mass transfer coefficient (α). Results were obtained for a wide range of aggregate porosities (between 0.082 and 0.700). The effect of aggregate permeability was explored by varying pore throat sizes within the aggregates. Solute breakthrough curves (BTCs) obtained with the pore-scale network model at several locations along the domain were analysed using analytical solutions of the dual-porosity model to obtain estimates of ϕm and α. An increase in aggregate porosity was found to decrease ϕm and increase α, leading to considerable tailing in the BTCs. Changes in the aggregate pore throat size affected the relative flow velocity between the intra- and inter-aggregate domains. Higher flow velocities within the aggregates caused a change in the transport regime from diffusion dominated to more advection dominated. This change increased the exchange rate of solutes between the mobile and immobile domains, with a related increase in the value of the mass transfer coefficient and less tailing in the BTCs.

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.04.013
      Issue No: Vol. 105 (2017)
  • Looking for the Signal: A guide to iterative noise and artefact removal in
           X-ray tomographic reconstructions of porous geomaterials
    • Authors: S. Bruns; S.L.S. Stipp; H.O. Sørensen
      Pages: 96 - 107
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): S. Bruns, S.L.S. Stipp, H.O. Sørensen
      X-ray micro- and nanotomography has evolved into a quantitative analysis tool rather than a mere qualitative visualization technique for the study of porous natural materials. Tomographic reconstructions are subject to noise that has to be handled by image filters prior to quantitative analysis. Typically, denoising filters are designed to handle random noise, such as Gaussian or Poisson noise. In tomographic reconstructions, noise has been projected from Radon space to Euclidean space, i.e. post reconstruction noise cannot be expected to be random but to be correlated. Reconstruction artefacts, such as streak or ring artefacts, aggravate the filtering process so algorithms performing well with random noise are not guaranteed to provide satisfactory results for X-ray tomography reconstructions. With sufficient image resolution, the crystalline origin of most geomaterials results in tomography images of objects that are untextured. We developed a denoising framework for these kinds of samples that combines a noise level estimate with iterative nonlocal means denoising. This allows splitting the denoising task into several weak denoising subtasks where the later filtering steps provide a controlled level of texture removal. We describe a hands-on explanation for the use of this iterative denoising approach and the validity and quality of the image enhancement filter was evaluated in a benchmarking experiment with noise footprints of a varying level of correlation and residual artefacts. They were extracted from real tomography reconstructions. We found that our denoising solutions were superior to other denoising algorithms, over a broad range of contrast-to-noise ratios on artificial piecewise constant signals.

      PubDate: 2017-05-16T05:12:31Z
      DOI: 10.1016/j.advwatres.2017.04.020
      Issue No: Vol. 105 (2017)
  • The effect of deformation on two-phase flow through proppant-packed
           fractured shale samples: A micro-scale experimental investigation
    • Authors: Maziar Arshadi; Arsalan Zolfaghari; Mohammad Piri; Ghaithan A. Al-Muntasheri; Mohammed Sayed
      Pages: 108 - 131
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): Maziar Arshadi, Arsalan Zolfaghari, Mohammad Piri, Ghaithan A. Al-Muntasheri, Mohammed Sayed
      We present the results of an extensive micro-scale experimental investigation of two-phase flow through miniature, fractured reservoir shale samples that contained different packings of proppant grains. We investigated permeability reduction in the samples by conducting experiments under a wide range of net confining pressures. Three different proppant grain distributions in three individual fractured shale samples were studied: i) multi-layer, ii) uniform mono-layer, and iii) non-uniform mono-layer. We performed oil-displacing-brine (drainage) and brine-displacing-oil (imbibition) flow experiments in the proppant packs under net confining pressures ranging from 200 to 6000  psi. The flow experiments were performed using a state-of-the-art miniature core-flooding apparatus integrated with a high-resolution, X-ray microtomography system. We visualized fluid occupancies, proppant embedment, and shale deformation under different flow and stress conditions. We examined deformation of pore space within the proppant packs and its impact on permeability and residual trapping, proppant embedment due to changes in net confining stress, shale surface deformation, and disintegration of proppant grains at high stress conditions. In particular, geometrical deformation and two-phase flow effects within the proppant pack impacting hydraulic conductivity of the medium were probed. A significant reduction in effective oil permeability at irreducible water saturation was observed due to increase in confining pressure. We propose different mechanisms responsible for the observed permeability reduction in different fracture packings. Samples with dissimilar proppant grain distributions showed significantly different proppant embedment behavior. Thinner proppant layer increased embedment significantly and lowered the onset confining pressure of embedment. As confining stress was increased, small embedments caused the surface of the shale to fracture. The produced shale fragments were then entrained by the flow and partially blocked pore-throat connections within the proppant pack. Deformation of proppant packs resulted in significant changes in waterflood residual oil saturation. In-situ contact angles measured using micro-CT images showed that proppant grains had experienced a drastic alteration of wettability (from strong water-wet to weakly oil-wet) after the medium had been subjected to flow of oil and brine for multiple weeks. Nanometer resolution SEM images captured nano-fractures induced in the shale surfaces during the experiments with mono-layer proppant packing. These fractures improved the effective permeability of the medium and shale/fracture interactions.

      PubDate: 2017-05-16T05:12:31Z
      DOI: 10.1016/j.advwatres.2017.04.022
      Issue No: Vol. 105 (2017)
  • A new way to parameterize hydraulic conductances of pore elements: A step
           towards creating pore-networks without pore shape simplifications
    • Authors: Xiuxiu Miao; Kirill M. Gerke; Timofey O. Sizonenko
      Pages: 162 - 172
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): Xiuxiu Miao, Kirill M. Gerke, Timofey O. Sizonenko
      Pore-network models were found useful in describing important flow and transport mechanisms and in predicting flow properties of different porous media relevant to numerous fundamental and industrial applications. Pore-networks provide very fast computational framework and permit simulations on large volumes of pores. This is possible due to significant pore space simplifications and linear/exponential relationships between effective properties and geometrical characteristics of the pore elements. To make such relationships work, pore-network elements are usually simplified by circular, triangular, square and other basic shapes. However, such assumptions result in inaccurate prediction of transport properties. In this paper, we propose that pore-networks can be constructed without pore shape simplifications. To test this hypothesize we extracted 3292 2D pore element cross-sections from 3D X-ray microtomography images of sandstone and carbonate rock samples. Based on the circularity, convexity and elongation of each pore element we trained neural networks to predict the dimensionless hydraulic conductance. The optimal neural network provides 90% of predictions lying within the 20% error bounds compared against direct numerical simulation results. Our novel approach opens a new way to parameterize pore-networks and we outlined future improvements to create a new class of pore-network models without pore shape simplifications.
      Graphical abstract image

      PubDate: 2017-05-16T05:12:31Z
      DOI: 10.1016/j.advwatres.2017.04.021
      Issue No: Vol. 105 (2017)
  • Relating recent random walk models with classical perturbation theory for
           dispersion predictions in the heterogeneous porous subsurface
    • Authors: Daniel W. Meyer
      Pages: 227 - 232
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): Daniel W. Meyer
      Recently developed stochastic macro-dispersion models enable computationally inexpensive flow and transport predictions for highly heterogeneous formations with statistically non-stationary conductivity and flow statistics. So far, the random processes at the heart of these models have been calibrated numerically based on velocity statistics from Monte Carlo simulation studies. In this work, we provide a more rigorous foundation to some of these models by analytically relating the process definition to given velocity statistics from classical first-order perturbation expansions.

      PubDate: 2017-05-25T13:13:33Z
      DOI: 10.1016/j.advwatres.2017.04.017
      Issue No: Vol. 105 (2017)
  • Comments on “An improved Cauchy number approach for predicting the drag
           and reconfiguration of flexible vegetation” by Peter Whittaker,
           Catherine A.M.E. Wilson, and Jochen Aberle
    • Authors: Li Chen; Xiaobing Chen
      Pages: 233 - 235
      Abstract: Publication date: July 2017
      Source:Advances in Water Resources, Volume 105
      Author(s): Li Chen, Xiaobing Chen

      PubDate: 2017-06-10T06:09:32Z
      DOI: 10.1016/j.advwatres.2016.10.017
      Issue No: Vol. 105 (2017)
  • Modeling anisotropy in free-surface overland and shallow inundation flows
    • Authors: Daniele Pietro Viero; Mohammad Valipour
      Pages: 1 - 14
      Abstract: Publication date: Available online 12 March 2017
      Source:Advances in Water Resources
      Author(s): Daniele Pietro Viero, Mohammad Valipour
      Regular patterns, which are found in both natural and man-modified environments, are strongly interwoven with free-surface flows. Examples are ridge and slough landscapes, cultivated terrains with ditches and furrows, and urban areas, with many of them characterized by a marked anisotropy. Simulation of overland and shallow inundation flows in these contexts is complex and demanding, especially if very different spatial scales are involved. Anisotropic effects are introduced to cope with two-dimensional shallow water models and, particularly, with the subgrid modeling technique. Application to schematic test cases shows the key role played by anisotropy in shallow flows, and second, that anisotropy can be effectively captured by the subgrid model with low computational effort and preserving mesh-independentness. High-resolution model results are accurately reproduced on coarser meshes using one fiftieth of the original computational elements, with a speed-up of more than 20. The subgrid approach could serve in view of physically based, large-scale modeling of floodplain inundation processes, in irrigation science, and in high-resolution hydrodynamic-hydrological simulations at the basin scale.

      PubDate: 2017-03-17T19:21:57Z
      DOI: 10.1016/j.advwatres.2017.03.007
      Issue No: Vol. 104 (2017)
  • Simulation of mixing-limited reactions using a continuum approach
    • Authors: Jack M. Barnard
      Pages: 15 - 22
      Abstract: Publication date: Available online 15 March 2017
      Source:Advances in Water Resources
      Author(s): Jack M. Barnard
      The limiting of reaction rates in porous media due to the imperfect mixing of reactants is a well studied phenomenon. It has been observed on both the field and laboratory scale and studied using a range of numerical techniques including continuum approaches and Lagrangian particle tracking methods. A new method is presented here for the simulation of mixing-limited reactions using continuum methods, based on the idea of separating each reactant into a mixed and an unmixed fraction, of which only the mixed fraction can react. The method is shown to be capable of producing mixing-limited reaction rates associated with one-, two-, and three-dimensional systems, and of producing outputs well fitted to the experimental data presented in Gramling et al. [1].

      PubDate: 2017-03-17T19:21:57Z
      DOI: 10.1016/j.advwatres.2017.03.012
      Issue No: Vol. 104 (2017)
  • Quantifying the impact of early calcite cementation on the reservoir
           quality of carbonate rocks: A 3D process-based model
    • Authors: Aleksandra Hosa; Rachel Wood
      Pages: 89 - 104
      Abstract: Publication date: June 2017
      Source:Advances in Water Resources, Volume 104
      Author(s): Aleksandra Hosa, Rachel Wood
      The reservoir properties of carbonate rocks are controlled by both deposition and diagenesis. The latter includes the early precipitation of calcite cements, which can exert a strong control on the evolution of subsequent diagenetic pathways. We quantify the impact of early marine cement growth in grainstones on evolving pore space by examining trends in the relationship between cementation and permeability using a 3D process-based model (Calcite3D). The model assumes varying proportions of polycrystalline and monocrystalline grain types, upon which we grow isopachous and syntaxial calcite cement types, respectively. We model two syntaxial cement shapes, compact and elongated, that approximate the geometries of typical rhombohedral calcite forms. Results demonstrate the effect of cement competition: an increasing proportion of monocrystalline grains creates stronger competition and a reduction in the impact of individual grains on final calcite cement volume and porosity. Isopachous cement is effective in closing pore throats and limiting permeability. We also show that the impact of syntaxial cement on porosity occlusion and therefore flow is highly dependent on monocrystalline grain location and the orientation of crystal axes. This demonstrates the importance of diagenetic overprint in controlling the evolution of rock properties, but also that this process can be essentially random. We also show that diagenesis alone can create notable heterogeneity in the permeability of carbonates. While Calcite3D is successful in modelling realistic changes in cement volumes and pore space morphology, modelled permeabilities (0.01 − 30D) are above the range reported in reservoir grainstones due to the very high permeability of the initial synthetic sediment deposit (58.9D). Poroperm data generated by Calcite3D, however, exhibits a linear relationship between the logarithms of porosity and permeability with a high coefficient of determination, as observed in natural media.

      PubDate: 2017-03-25T21:12:47Z
      DOI: 10.1016/j.advwatres.2017.02.019
      Issue No: Vol. 104 (2017)
  • Upscaling soil saturated hydraulic conductivity from pore throat
    • Authors: Behzad Ghanbarian; Allen G. Hunt; Todd H. Skaggs; Nicholas Jarvis
      Pages: 105 - 113
      Abstract: Publication date: June 2017
      Source:Advances in Water Resources, Volume 104
      Author(s): Behzad Ghanbarian, Allen G. Hunt, Todd H. Skaggs, Nicholas Jarvis
      Upscaling and/or estimating saturated hydraulic conductivity K sat at the core scale from microscopic/macroscopic soil characteristics has been actively under investigation in the hydrology and soil physics communities for several decades. Numerous models have been developed based on different approaches, such as the bundle of capillary tubes model, pedotransfer functions, etc. In this study, we apply concepts from critical path analysis, an upscaling technique first developed in the physics literature, to estimate saturated hydraulic conductivity at the core scale from microscopic pore throat characteristics reflected in capillary pressure data. With this new model, we find K sat estimations to be within a factor of 3 of the average measured saturated hydraulic conductivities reported by Rawls et al. (1982) for the eleven USDA soil texture classes.

      PubDate: 2017-03-25T21:12:47Z
      DOI: 10.1016/j.advwatres.2017.03.016
      Issue No: Vol. 104 (2017)
  • Sediment heterogeneity and mobility in the morphodynamic modelling of
           gravel-bed braided rivers
    • Authors: Umesh Singh; Alessandra Crosato; Sanjay Giri; Murray Hicks
      Pages: 127 - 144
      Abstract: Publication date: June 2017
      Source:Advances in Water Resources, Volume 104
      Author(s): Umesh Singh, Alessandra Crosato, Sanjay Giri, Murray Hicks
      The effects of sediment heterogeneity and sediment mobility on the morphology of braided rivers are still poorly studied, especially when the partial sediment mobility occurs. Nevertheless, increasing the bed sediment heterogeneity by coarse sediment supply is becoming a common practice in river restoration projects and habitat improvement all over the world. This research provides a step forward in the identification of the effects of sediment sorting on the evolution of sediment bars and braiding geometry of gravel-bed rivers. A two-dimensional morphodynamic model was used to simulate the long-term developments of a hypothetical braided system with discharge regime and morphodynamic parameters derived from the Waimakariri River, New Zealand. Several scenarios, differing in bed sediment heterogeneity and sediment mobility, were considered. The results agree with the tendencies already identified in linear analyses and experimental studies, showing that a larger sediment heterogeneity increases the braiding indes and reduces the bars length and height. The analyses allowed identifying the applicability limits of uniform sediment and variable discharge modelling approaches.

      PubDate: 2017-04-01T19:58:02Z
      DOI: 10.1016/j.advwatres.2017.02.005
      Issue No: Vol. 104 (2017)
  • 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
  • Transient Modeling of Non-Fickian Transport and First-Order Reaction Using
           Continuous Time Random Walk
    • Authors: Daniel K. Burnell; Scott K. Hansen; Jie Xu
      Abstract: Publication date: Available online 19 June 2017
      Source:Advances in Water Resources
      Author(s): Daniel K. Burnell, Scott K. Hansen, Jie Xu
      Contaminants in groundwater may experience a broad spectrum of velocities and multiple rates of mass transfer between mobile and immobile zones during transport. These conditions may lead to non-Fickian plume evolution which is not well described by the advection-dispersion equation (ADE). Simultaneously, many groundwater contaminants are degraded by processes that may be modeled as first-order decay. It is now known that non-Fickian transport and reaction are intimately coupled, with reaction affecting the transport operator. However, closed-form solutions for these important scenarios have not been published for use in applications. In this paper, we present four new Green's function analytic solutions in the uncoupled, uncorrelated continuous time random walk (CTRW) framework for reactive non-Fickian transport, corresponding to the quartet of conservative tracer solutions presented by Kreft and Zuber (1978) for Fickian transport. These consider pulse injection for both resident and flux concentration combined with detection in both resident and flux concentration. A pair of solutions for resident concentration temporal pulses with detection in both flux and resident concentration is also presented. We also derive the relationship between flux and resident concentration for non-Fickian transport with first-order reaction for this CTRW formulation. An explicit discussion of employment of the new solutions to model transport with arbitrary upgradient boundary conditions as well as mobile-immobile mass transfer is then presented. Using the new solutions, we show that first-order reaction has no effect on the anomalous spatial spreading rate of concentration profiles, but produces breakthrough curves at fixed locations that appear to have been generated by Fickian transport. Under the assumption of a Pareto CTRW transition distribution, we present a variety of numerical simulations including results showing coherence of our analytic solutions and CTRW particle tracking.

      PubDate: 2017-06-20T09:47:26Z
      DOI: 10.1016/j.advwatres.2017.06.014
  • 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
  • Equivalence of turbulence statistics between monodisperse and polydisperse
           turbidity currents
    • Authors: Mrugesh Shringarpure; Mariano I. Cantero; S. Balachandar
      Abstract: Publication date: Available online 7 June 2017
      Source:Advances in Water Resources
      Author(s): Mrugesh Shringarpure, Mariano I. Cantero, S. Balachandar
      Turbidity currents are buoyancy driven submarine flows where the source of buoyancy is typically a polydisperse sediment suspension. Sustained propagation of such flows depend on the ability of turbulence in the flow to keep the settling sediments in suspension. Recent studies by Cantero et al. (2012b) and Shringarpure et al. (2012) have investigated the interaction of monodisperse sediment suspension and turbulence in turbidity currents on smooth sloping beds. These studies showed that stable stratification of sediment suspension damps turbulence and in some cases can be fully suppress turbulence. Furthermore, it was shown that the turbulence damping effect of a monodisperse sediment suspension can be quantified by the product of shear Richardson number and the sediment settling velocity. In this study we generalize this result for a polydisperse sediment suspension. We compare the turbulence statistics of turbidity currents driven by different polydisperse suspensions and show that as long as the total amount of sediment and the product of shear Richardson number and effective settling velocity (a value representing the polydisperse suspension) are the same, the turbulent velocity statistics of the different polydisperse suspensions nearly collapse. Furthermore, if the effective settling velocity is chosen to be depth-dependent (a function of height from the bed) then the turbulence statistics involving sediment concentration also collapses between different polydisperse suspensions. These results suggest the possibility of modeling polydisperse currents with an equivalent monodisperse suspension whose total sediment load and depth-dependent settling velocity match those of the polydisperse suspension.

      PubDate: 2017-06-10T06:09:32Z
      DOI: 10.1016/j.advwatres.2017.05.015
  • 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
  • Projection-based Embedded Discrete Fracture Model (pEDFM)
    • Authors: Matei Ţene; Sebastian B.M. Bosma; Mohammed Saad Al Kobaisi; Hadi Hajibeygi
      Abstract: Publication date: Available online 15 May 2017
      Source:Advances in Water Resources
      Author(s): Matei Ţene, Sebastian B.M. Bosma, Mohammed Saad Al Kobaisi, Hadi Hajibeygi
      This work presents a new discrete fracture model, namely the Projection-based Embedded Discrete Fracture Model (pEDFM). Similar to the existing EDFM approach, pEDFM constructs independent grids for the matrix and fracture domains, and delivers strictly conservative velocity fields. However, as a significant step forward, it is able to accurately model the effect of fractures with general conductivity contrasts relative to the matrix, including impermeable flow barriers. This is achieved by automatically adjusting the matrix transmissibility field, in accordance to the conductivity of neighboring fracture networks, alongside the introduction of additional matrix-fracture connections. The performance of pEDFM is investigated extensively for two- and three-dimensional scenarios involving single-phase as well as multiphase flows. These numerical experiments are targeted at determining the sensitivity of the model towards the fracture position within the matrix control volume, grid resolution and the conductivity contrast towards the matrix. The pEDFM significantly outperforms the original EDFM and produces results comparable to those obtained when using DFM on unstructured grids, therefore proving to be a flexible model for field-scale simulation of flow in naturally fractured reservoirs.

      PubDate: 2017-05-16T05:12:31Z
      DOI: 10.1016/j.advwatres.2017.05.009
  • A Novel Generic Optimization Method for Irrigation Scheduling under
           Multiple Objectives and Multiple Hierarchical Layers in a Canal Network
    • Authors: Dilini Delgoda; Hector Malano; Syed K. Saleem; Malka N. Halgamuge
      Abstract: Publication date: Available online 10 May 2017
      Source:Advances in Water Resources
      Author(s): Dilini Delgoda, Hector Malano, Syed K. Saleem, Malka N. Halgamuge
      This research proposes a novel generic method for irrigation scheduling in a canal network, capable of optimizing multiple objectives related to canal scheduling (e.g. maximizing water supply and minimizing imbalance of water distribution) within multiple hierarchical layers (e.g. the layers consisting of the main canal, distributaries) while utilizing traditional canal scheduling methods. It is based on modularizing the optimization process. The method is theoretically capable of optimizing an unlimited number of user-defined objectives within an unlimited number of hierarchical layers and only limited by resource availability (e.g. maximum canal capacity and water limitations) in the network. It allows flexible decision-making through quantification of the mutual effects of optimizing conflicting objectives and is adaptable to available multi-objective evolutionary algorithms. The method’s application is demonstrated using a hypothetical canal network example with six objectives and three hierarchical layers, and a real scenario with four objectives and two layers.

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.04.025
  • Numerical determination of vertical water flux based on soil temperature
    • Authors: Alain Tabbagh; Bruno Cheviron; Hocine Henine; Roger Guérin; Mohamed-Amine Bechkit
      Abstract: Publication date: Available online 10 May 2017
      Source:Advances in Water Resources
      Author(s): Alain Tabbagh, Bruno Cheviron, Hocine Henine, Roger Guérin, Mohamed-Amine Bechkit
      High sensitivity temperature sensors (0.001 K sensitivity Pt100 thermistors), positioned at intervals of a few centimetres along a vertical soil profile, allow temperature measurements to be made which are sensitive to water flux through the soil. The development of high data storage capabilities now makes it possible to carry out in situ temperature recordings over long periods of time. By directly applying numerical models of convective and conductive heat transfer to experimental data recorded as a function of depth and time, it is possible to calculate Darcy's velocity from the convection transfer term, thus allowing water infiltration/exfiltration through the soil to be determined as a function of time between fixed depths. In the present study we consider temperature data recorded at the Boissy-le-Châtel (Seine et Marne, France) experimental station between April 16th, 2009 and March 8th, 2010, at six different depths and 10-min time intervals. We make use of two numerical finite element models to solve the conduction/convection heat transfer equation and compare their merits. These two models allow us to calculate the corresponding convective flux rate every day using a group of three sensors. The comparison of the two series of calculated values centred at 24 cm shows reliable results for periods longer than 8 days. These results are transformed in infiltration/exfiltration value after determining the soil volumetric heat capacity. The comparison with the rainfall and evaporation data for periods of ten days shows a close accordance with the behaviour of the system governed by rainfall evaporation rate during winter and spring.
      Graphical abstract image

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.05.003
  • Micro-scale Displacement of NAPL by Surfactant and Microemulsion in
           Heterogeneous Porous Media
    • Authors: Gina Javanbakht; Maziar Arshadi; Tianzhu Qin; Lamia Goual
      Abstract: Publication date: Available online 9 May 2017
      Source:Advances in Water Resources
      Author(s): Gina Javanbakht, Maziar Arshadi, Tianzhu Qin, Lamia Goual
      Industrial processes such as remediation of oil-contaminated aquifers and enhanced oil recovery (EOR) often utilize chemical additives to increase the removal of non-aqueous phase liquids (NAPLs) from subsurface formations. Although the majority of crude oils are classified as LNAPLs, they often contain heavy molecules (DNAPLs) such as asphaltenes that tend to adsorb on minerals and alter their wettability. Effective additives are therefore those that can reduce the threshold capillary pressure, thus mobilizing LNAPL inside pore spaces and solubilizing DNAPL from rock surfaces. Nonionic surfactants in brine have often been injected to oil or contaminated aquifer formations in order to enhance NAPL displacement through IFT reduction. Recent studies revealed that surfactant-based microemulsions have a higher tendency to alter the wettability of surfaces, compared to surfactants alone, leading to more effective NAPL removal. However, the impact of these additives on pore-scale displacement mechanisms and multi-phase fluid occupancy in porous media is, to date, still unclear. In this study, x-ray microtomography experiments were performed to investigate the impact of surfactants and microemulsions on the mobilization and solubilization of NAPL in heterogeneous rocks. Saturation profiles indicated that an incremental NAPL removal was attained by addition of microemulsion to brine, compared with surfactant. Residual cluster size distributions revealed that microemulsions could break up large clusters into smaller disconnected ones, improving their mobilization in the rock. In-situ contact angle measurements showed that microemulsions could reverse the wettability of rough contaminated surfaces to a higher extent than surfactants. Unlike surfactant alone, the surfactant-solvent blend in the carrier fluid of microemulsions was able to penetrate rough grain surfaces, particularly those of dolomite cement, and desorb asphaltenes in the form of small-emulsified NAPL droplets, which were eventually washed away by the continuous flow process. The greater wettability alteration caused by microemulsions resulted in a lower threshold capillary pressure, which in turn promoted the mobilization of NAPL ganglia more than surfactant alone.
      Graphical abstract image

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.05.006
  • Impact of type of salt and ambient conditions on saline water evaporation
           from porous media
    • Authors: Salomé M.S. Shokri-Kuehni; Mansoureh Norouzirad; Colin Webb; Nima Shokri
      Abstract: Publication date: Available online 8 May 2017
      Source:Advances in Water Resources
      Author(s): Salomé M.S. Shokri-Kuehni, Mansoureh Norouzirad, Colin Webb, Nima Shokri
      Saline water evaporation from porous media is important in many processes such as soil salinization, CO2 sequestration, crop production and water management. This process is influenced by the transport properties of porous media, properties of the evaporating solution and external conditions. In this work, we investigated the effects of external conditions and type of salt on the drying behaviour of sandy media and on the dynamics of surface salt precipitation. To do so, a comprehensive series of evaporation experiments were conducted using 33 columns packed with sand saturated with salt solutions. The evaporation experiments were conducted in an environmental chamber to investigate the effects of relative humidity, ambient temperature and type of salt on the evaporation process. Sodium Chloride, Calcium Chloride and Potassium Iodide with a wide range of concentration were used to saturate the sand columns mounted on digital balances. A digital camera was fixed at the surface of the sand packs to record the dynamics of salt precipitation at the surface. The results provide further confirmation that ambient conditions are the controlling factors during stage-1 evaporation of pure water. Additionally, the minor impact of the presence of precipitated salt at the surface on the saline water evaporation during the early stages of the process is discussed. Strong correlations between the cumulative water losses and the precipitation at the surface were found under different ambient conditions. The results obtained from different types of salt highlight the significant influence of the relationship between the saturated vapour pressure and salt concentration on the general dynamics of the process.

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.05.004
  • Considering historical flood events in flood frequency analysis: Is it
           worth the effort?
    • Authors: Thomas Schendel; Rossukon Thongwichian
      Abstract: Publication date: Available online 6 May 2017
      Source:Advances in Water Resources
      Author(s): Thomas Schendel, Rossukon Thongwichian
      Information about historical floods can be useful in reducing uncertainties in flood frequency estimation. Since the start of the historical record is often defined by the first known flood, the length of the true historical period M remains unknown. We have expanded a previously published method of estimating M to the case of several known floods within the historical period. We performed a systematic evaluation of the usefulness of including historical flood events into flood frequency analysis for a wide range of return periods and studied bias as well as relative root mean square error (RRMSE). Since we used the generalized extreme value distribution (GEV) as parent distribution, we were able to investigate the impact of varying the skewness on RRMSE. We confirmed the usefulness of historical flood data regarding the reduction of RRMSE, however we found that this reduction is less pronounced the more positively skewed the parent distribution was. Including historical flood information had an ambiguous effect on bias: depending on length and number of known floods of the historical period, bias was reduced for large return periods, but increased for smaller ones. Finally, we customized the test inversion bootstrap for estimating confidence intervals to the case that historical flood events are taken into account into flood frequency analysis.

      PubDate: 2017-05-11T05:05:11Z
      DOI: 10.1016/j.advwatres.2017.05.002
  • Numerical modeling of open channel flow with suspended canopy
    • Authors: Fang Zhao; Wenxin Huai; Dan Li
      Abstract: Publication date: Available online 5 May 2017
      Source:Advances in Water Resources
      Author(s): Fang Zhao, Wenxin Huai, Dan Li
      Suspended canopies are common in aquatic environments. The mean flow velocity and Reynolds stress in the open channels with the suspended canopies were studied through laboratory experiments and numerical simulations. Numerical modelling was conducted with a modified version of the Delft3D-Flow model using a k – ε turbulence closure scheme. The resistance effects of the suspended canopy were modeled by adding a resistance term in the momentum equations of fluid flow, along with an addition production and dissipation term in the k and ε equations respectively. The numerical results for mean flow velocity and Reynolds stress agreed well with the experimental data of this study and the previously published data by Plew (2010). The spatial evolution of the mixing layer near the bottom of the suspended canopy can be broadly separated into the diverging flow, developing, and fully developed zones. The thickness and density of the suspended canopy significantly influenced the flow characteristics.

      PubDate: 2017-05-06T07:04:11Z
      DOI: 10.1016/j.advwatres.2017.05.001
  • Optimal Moment Determination in POME-copula based Hydrometeorological
           Dependence Modelling
    • Authors: Dengfeng Liu; Dong Wang; Vijay P. Singh; Yuankun Wang; Jichun Wu; Lachun Wang; Xinqing Zou; Yuanfang Chen; Xi Chen
      Abstract: Publication date: Available online 27 April 2017
      Source:Advances in Water Resources
      Author(s): Dengfeng Liu, Dong Wang, Vijay P. Singh, Yuankun Wang, Jichun Wu, Lachun Wang, Xinqing Zou, Yuanfang Chen, Xi Chen
      Copula has been commonly applied in multivariate modelling in various fields where marginal distribution inference is a key element. To develop a flexible, unbiased mathematical inference framework in hydrometeorological multivariate applications, the principle of maximum entropy (POME) is being increasingly coupled with copula. However, in previous POME-based studies, determination of optimal moment constraints has generally not been considered. The main contribution of this study is the determination of optimal moments for POME for developing a coupled optimal moment-POME-copula framework to model hydrometeorological multivariate events. In this framework, margins (marginals, or marginal distributions) are derived with the use of POME, subject to optimal moment constraints. Then, various candidate copulas are constructed according to the derived margins, and finally the most probable one is determined, based on goodness-of-fit statistics. This optimal moment-POME-copula framework is applied to model the dependence patterns of three types of hydrometeorological events: (i) single-site streamflow-water level; (ii) multi-site streamflow; and (iii) multi-site precipitation, with data collected from Yichang and Hankou in the Yangtze River basin, China. Results indicate that the optimal-moment POME is more accurate in margin fitting and the corresponding copulas reflect a good statistical performance in correlation simulation. Also, the derived copulas, capturing more patterns which traditional correlation coefficients cannot reflect, provide an efficient way in other applied scenarios concerning hydrometeorological multivariate modelling.

      PubDate: 2017-04-30T07:02:30Z
      DOI: 10.1016/j.advwatres.2017.04.016
  • Calibrating a hydrological model in stage space to account for rating
           curve uncertainties: general framework and key challenges
    • Authors: Anna E. Sikorska; Benjamin Renard
      Abstract: Publication date: Available online 26 April 2017
      Source:Advances in Water Resources
      Author(s): Anna E. Sikorska, Benjamin Renard
      Hydrological models are typically calibrated with discharge time series derived from a rating curve, which is subject to parametric and structural uncertainties that are usually neglected. In this work, we develop a Bayesian approach to probabilistically represent parametric and structural rating curve errors in the calibration of hydrological models. To achieve this, we couple the hydrological model with the inverse rating curve yielding the rainfall-stage model that is calibrated in stage space. Acknowledging uncertainties of the hydrological and the rating curve models allows assessing their contribution to total uncertainties of stages and discharges. Our results from a case study in France indicate that a) ignoring rating curve uncertainty leads to changes in hydrological parameters, and b) structural uncertainty of hydrological model dominates other uncertainty sources. The paper ends with discussing key challenges that remain to be addressed to achieve a meaningful quantification of various uncertainty sources that affect hydrological model, as including input errors.
      Graphical abstract image

      PubDate: 2017-04-30T07:02:30Z
      DOI: 10.1016/j.advwatres.2017.04.011
  • An efficient stochastic approach for flow in porous media via sparse
           polynomial chaos expansion constructed by feature selection
    • Authors: Jin Meng; Heng Li
      Abstract: Publication date: Available online 26 April 2017
      Source:Advances in Water Resources
      Author(s): Jin Meng, Heng Li
      An efficient method for uncertainty quantification for flow in porous media is studied in this paper, where response surface of sparse polynomial chaos expansion (PCE) is constructed with the aid of feature selection method. The number of basis functions in PCE grows exponentially as the random dimensionality increases, which makes the computational cost unaffordable in high-dimensional problems. In this study, a feature selection method is introduced to select major stochastic features for the PCE by running a limited number of simulations, and the resultant PCE is termed as sparse PCE. Specifically, the least absolute shrinkage and selection operator modified least angle regression algorithm (LASSO-LAR) is applied for feature selection and the selected features are assessed by cross-validation (CV). Besides, inherited samples are utilized to make the algorithm self-adaptive. In this study, we test the performance of sparse PCE for uncertainty quantification for flow in heterogeneous media with different spatial variability. The statistical moments and probability density function of the output random field are accurately estimated through the sparse PCE, meanwhile the computational efforts are greatly reduced compared to the Monte Carlo method.

      PubDate: 2017-04-30T07:02:30Z
      DOI: 10.1016/j.advwatres.2017.04.019
  • Development of a Passive Sensor for Measuring Vertical Cumulative Water
           and Solute Mass Fluxes in Lake Sediments and Streambeds
    • Authors: Leif Layton; Harald Klammler; Kirk Hatfield; Jaehyun Cho; Mark A. Newman; Michael D. Annable
      Abstract: Publication date: Available online 26 April 2017
      Source:Advances in Water Resources
      Author(s): Leif Layton, Harald Klammler, Kirk Hatfield, Jaehyun Cho, Mark A. Newman, Michael D. Annable
      This paper introduces the sediment bed passive flux meter (SBPFM) as a new tool for in situ measurements of vertical volumetric water and contaminant mass fluxes across hyporheic and hypolentic zones (i.e., stream or lake bed sediments that function as the contiguous zone between the overlying surface water body and the underlying aquifer). The device is a direct-push probe which contains a permeable internal sorbent located between two screened intervals. In the presence of a vertical hydraulic gradient the screens allow water flow through the SBPFM's internal sorbent matrix that is impregnated with resident tracers. These tracers are displaced from the sorbent at rates proportional to the water flux through the sorbent. At the same time, dissolved contaminants present in the intercepted sediment water are retained on the SBPFM sorbent at rates proportional to the ambient contaminant mass flux in the hyporheic zone. Potential flow theory is applied to convert observations of water and contaminant fluxes through the SBPFM into estimates of undisturbed ambient vertical water and contaminant fluxes in the sediment. To validate the theory and demonstrate the SBPFM as a potential site characterization tool, multiple bench-scale sediment bed experiments are performed. Results demonstrate that water and contaminant mass fluxes are accurately measured in the laboratory and that future field tests are warranted.

      PubDate: 2017-04-30T07:02:30Z
      DOI: 10.1016/j.advwatres.2017.04.018
  • Modeling variability in porescale multiphase flow experiments
    • Authors: Bowen Ling; Jie Bao; Mart Oostrom; Ilenia Battiato; Alexandre M. Tartakovsky
      Abstract: Publication date: Available online 11 April 2017
      Source:Advances in Water Resources
      Author(s): Bowen Ling, Jie Bao, Mart Oostrom, Ilenia Battiato, Alexandre M. Tartakovsky
      Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e.,fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rate. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

      PubDate: 2017-04-16T03:06:57Z
      DOI: 10.1016/j.advwatres.2017.04.005
  • A reduced order model to analytically infer atmospheric CO2 concentration
           from stomatal and climate data
    • Authors: Wilfried Konrad; Gabriel Katul; Anita Roth-Nebelsick; Michaela Grein
      Abstract: Publication date: Available online 25 March 2017
      Source:Advances in Water Resources
      Author(s): Wilfried Konrad, Gabriel Katul, Anita Roth-Nebelsick, Michaela Grein
      To address questions related to the acceleration or deceleration of the global hydrological cycle or links between the carbon and water cycles over land, reliable data for past climatic conditions based on proxies are required. In particular, the reconstruction of palaeoatmospheric CO2 content (Ca ) is needed to assist the separation of natural from anthropogenic Ca variability and to explore phase relations between Ca and air temperature Ta time series. Both Ta and Ca are needed to fingerprint anthropogenic signatures in vapour pressure deficit, a major driver used to explain acceleration or deceleration phases in the global hydrological cycle. Current approaches to Ca reconstruction rely on a robust inverse correlation between measured stomatal density in leaves (ν) of many plant taxa and Ca . There are two methods that exploit this correlation: The first uses calibration curves obtained from extant species assumed to represent the fossil taxa, thereby restricting the suitable taxa to those existing today. The second is a hybrid eco-hydrological/physiological approach that determines Ca with the aid of systems of equations based on quasi-instantaneous leaf-gas exchange theories and fossil stomatal data collected along with other measured leaf anatomical traits and parameters. In this contribution, a reduced order model (ROM) is proposed that derives Ca from a single equation incorporating the aforementioned stomatal data, basic climate (e.g. temperature), estimated biochemical parameters of assimilation and isotope data. The usage of the ROM is then illustrated by applying it to isotopic and anatomical measurements from three extant species. The ROM derivation is based on a balance between the biochemical demand and atmospheric supply of CO2 that leads to an explicit expression linking stomatal conductance to internal CO2 concentration (Ci ) and Ca . The resulting expression of stomatal conductance from the carbon economy of the leaf is then equated to another expression derived from water vapour gas diffusion that includes anatomical traits. When combined with isotopic measurements for long-term Ci /Ca, Ca can be analytically determined and is interpreted as the time-averaged Ca that existed over the life-span of the leaf. Key advantages of the proposed ROM are: 1) the usage of isotopic data provides constraints on the reconstructed atmospheric CO2 concentration from ν, 2) the analytical form of this approach permits direct links between parameter uncertainties and reconstructed Ca , and 3) the time-scale mismatch between the application of instantaneous leaf-gas exchange expressions constrained with longer-term isotopic data is reconciled through averaging rules and sensitivity analysis. The latter point was rarely considered in prior reconstruction studies that combined models of leaf-gas exchange and isotopic data to reconstruct Ca from ν. The proposed ROM is not without its limitations given the need to a priori assume a parameter related to the control on photosynthetic rate. The work here further explores immanent constraints for the aforementioned photosynthetic parameter.

      PubDate: 2017-03-25T21:12:47Z
      DOI: 10.1016/j.advwatres.2017.03.018
  • Estimating the water budget components and their variability in a
           Pre-Alpine basin with JGrass-NewAGE
    • Authors: Wuletawu Abera; Giuseppe Formetta; Marco Borga; Riccardo Rigon
      Abstract: Publication date: Available online 15 March 2017
      Source:Advances in Water Resources
      Author(s): Wuletawu Abera, Giuseppe Formetta, Marco Borga, Riccardo Rigon
      The estimation of water resources at basin scale requires modelling of all components of the hydrological system. Because of the great uncertainties associated with the estimation of each water cycle component and the large error in budget closure that results, water budget is rarely carried out explicitly. This paper fills the gap in providing a methodology for obtaining it routinely at daily and subdaily time scales. In this study, we use various strategies to improve water budget closure in a small basin of Italian Prealps. The specific objectives are: assessing the predictive performances of different Kriging methods to determine the most accurate precipitation estimates; using MODIS imagery data to assist in the separation of snowfall and rainfall; combining the Priestley-Taylor evapotranspiration model with the Budyko hypothesis to estimate at high resolution (in time and space) actual evapotranspiration (ET); using an appropriate calibration-validation strategy to forecast discharge spatially. For this, 18 years of spatial time series of precipitation, snow water equivalent, rainfall-runoff and ET at hourly time steps are simulated for the Posina River basin (Northeast Italy) using the JGrass-NewAGE system. Among the interpolation methods considered, local detrended kriging is seen to give the best performances in forecasting precipitation distribution. However, detrended Kriging gives better results in simulating discharges. The parameters optimized at the basin outlet over a five-year period show acceptable performances during the validation period at the outlet and at interior points of the basin. The use of the Budyko hypothesis to guide the ET estimation shows encouraging results, with less uncertainty than the values reported in literature. Aggregating at a long temporal scale, the mean annual water budget for the Posina River basin is about 1269 ± 372 mm (76.4%) runoff, 503.5 ± 35.5 mm (30%) evapotranspiration, and − 50 ± 129 mm (-4.2%) basin storage from basin precipitation of 1730 ± 344 mm. The highest interannual variability is shown for precipitation, followed by discharge. Evapotranspiration shows less interannual variability and is less dependent on precipitation.

      PubDate: 2017-03-17T19:21:57Z
      DOI: 10.1016/j.advwatres.2017.03.010
  • Convex Hull Approach for Determining Rock Representative Elementary Volume
           for Multiple Petrophysical Parameters using Pore-scale Imaging and
           Lattice-Boltzmann modelling
    • Authors: S.M. Shah; F. Gray; J. Yang; J.P. Crawshaw; E.S. Boek
      Abstract: Publication date: Available online 14 March 2017
      Source:Advances in Water Resources
      Author(s): S.M. Shah, F. Gray, J. Yang, J.P. Crawshaw, E.S. Boek
      In the last decade, the study of fluid flow in porous media has developed considerably due to the combination of X-ray Micro Computed Tomography (micro-CT) and advances in computational methods for solving complex fluid flow equations directly or indirectly on reconstructed three-dimensional pore space images. In this study, we calculate porosity and single phase permeability using micro-CT imaging and Lattice Boltzmann (LB) simulations for 8 different porous media: beadpacks (with bead sizes 50µm and 350 µm), sandpacks (LV60 and HST95), sandstones (Berea, Clashach and Doddington) and a carbonate (Ketton). Combining the observed porosity and calculated single phase permeability, we shed new light on the existence and size of the Representative Element of Volume (REV) capturing the different scales of heterogeneity from the pore-scale imaging. Our study applies the concept of the ‘Convex Hull’ to calculate the REV by considering the two main macroscopic petrophysical parameters, porosity and single phase permeability, simultaneously. The shape of the hull can be used to identify strong correlation between the parameters or greatly differing convergence rates. To further enhance computational efficiency we note that the area of the convex hull (for well-chosen parameters such as the log of the permeability and the porosity) decays exponentially with sub-sample size so that only a few small simulations are needed to determine the system size needed to calculate the parameters to high accuracy (small convex hull area). Finally we propose using a characteristic length such as the pore size to choose an efficient absolute voxel size for the numerical rock.

      PubDate: 2017-03-17T19:21:57Z
      DOI: 10.1016/j.advwatres.2017.03.008
  • Non-intrusive underwater measurement of mobile bottom surface
    • Authors: Shikha Chourasiya; P.K. Mohapatra; S. Tripathi
      Abstract: Publication date: Available online 14 March 2017
      Source:Advances in Water Resources
      Author(s): Shikha Chourasiya, P.K. Mohapatra, S. Tripathi
      This paper reports a novel approach for underwater measurement of mobile bottom surface by using an inexpensive 3-D depth sensor – Kinect. The sensor is tested in controlled conditions for surface profiling of rigid objects of different colors placed under varying water depths, turbidity, illuminosity and sensor height. Measurements indicate random errors are present when the object is in air only and these errors can be eliminated by smoothing. However, systematic errors were observed in the presence of water and are attributed to refraction. A refractive correction equation is developed to remove those systematic errors. Validation of the sensor's performance, quantification of its limitations and a systematic procedure for its use in underwater profiling is presented. Finally, capabilities of the sensor as an underwater measurement device for laboratory applications are demonstrated by measuring erosion of cross-stream sand bar due to overtopping and evolution of mining-pit.

      PubDate: 2017-03-17T19:21:57Z
      DOI: 10.1016/j.advwatres.2017.03.009
  • Identifying changing patterns of reservoir operating rules under various
           inflow alteration scenarios
    • Authors: Maoyuan Feng; Pan Liu; Shenglian Guo; Ziling Gui; Xiaoqi Zhang; Wei Zhang; Lihua Xiong
      Abstract: Publication date: Available online 8 March 2017
      Source:Advances in Water Resources
      Author(s): Maoyuan Feng, Pan Liu, Shenglian Guo, Ziling Gui, Xiaoqi Zhang, Wei Zhang, Lihua Xiong
      Operating rules are important in the long-term operation of reservoirs for its capability of coping with inflow uncertainty. The characteristics of inflow vary as a result of climate change and human activities, and using stationary operating rules would lead to inefficient reservoir operation. This study focuses on identifying changing patterns of operating rules under various inflow alteration scenarios. Two hydrological simulation methods, the simple adjustment method (SAM) and the stochastic reconstruction method (SRM), are used to generate three inflow alteration scenarios: shifts of mean, coefficient of variation (CV ), and seasonality. A deterministic reservoir optimization model is established and then resolved using discrete differential dynamic programming. Finally, the operating rules under each scenario are derived using the linear fitting method. China's Three Gorges Reservoir is used as a case study. The results show that the SAM and SRM produce similar operating rules, which are sensitive to inflow changes during refill and drawdown periods. It is shown that (1) the increase (decrease) of inflow mean changes the operating rules, resulting in the increase (decrease) of the water releases while the shift of CV has little impact on operating rules; (2) the seasonality changes operating rules in opposite directions during refill and drawdown periods; (3) the changing patterns of operating rules would be superimposed by the superposition of various inflow alteration scenarios whereas the effects might be not obvious. These findings are helpful for adaptive operation of reservoirs under changing environment.

      PubDate: 2017-03-10T13:20:26Z
      DOI: 10.1016/j.advwatres.2017.03.003
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