Many important groundwater transport applications require solving the Darcy flow in heterogeneous porous media. Flow simulations, especially in large, highly heterogeneous aquifers, require extensive computational resources, a multiresolution (multiscale) approach to resolve the different heterogeneity scales and an accurate calculation of the velocity field. Common methods, such as finite volumes

Using generalizations of the Cahn-Hilliard equation for modeling two-phase flow in porous media at the pore scale has become popular due to its ability to capture interfacial effects by adding minimal complications. Here we use upscaled field equations and exploit the second law of thermodynamics in the spirit of rational thermodynamics to develop a framework that, for two phases at the macroscale

This study concerns numerical methods for efficiently solving the Richards equation where different weak formulations and computational techniques are analyzed. The spatial discretizations are based on standard or mixed finite element methods. Different implicit and semi-implicit temporal discretization techniques of second-order accuracy are studied. To obtain a linear system for the semi-implicit

Aquatic vegetation dramatically shifts the main flow, secondary flow and turbulent structures in a meandering channel. In this study, hydrodynamics in a bending channel with a vegetation patch (VP) has been numerically studied under the variation of curvature ratios (CRs=0.5, 1.0, 1.5, 2.0) and the vegetation density i.e. Solid Volume Fractions (SVF=1.13%, 4.86%). Both effects on vegetation shear flow

Freezing of unsaturated soil is an important process that influences runoff and infiltration in cold-climate regions. We used a simple numerical model to simulate water and heat transport with phase change in unsaturated soil via three different approaches: empirical, semi-empirical and physically based. We compared the performance and parameterization of each approach through testing on three experimental

This work provides a comprehensive analysis of soil water dynamics in Australia for the climate projections of the Coupled Model Intercomparison Project 6 (CMIP6). We modelled the historical soil water dynamics from 1981 to 2018 at various depths within and below the root zone using the BRTSim computational solver to generate the "current conditions". We then investigated how the CMIP6 scenario can

Nanoparticle (NP) transport is increasingly relevant to subsurface engineering applications such as aquifer characterization and enhanced oil recovery. An efficient field-scale simulation framework is critical for predicting NP performance and designing subsurface applications. In this work, for the first time, a streamline-based model is presented to simulate NP transport in field-scale subsurface

Subsurface flow model calibration against dynamic response data is often constrained by a prior conceptual model of geologic scenario that specifies the expected spatial variability and patterns in the solution. However, significant uncertainty exists in developing a conceptual model, including data limitation, process-based modeling assumptions, and subjective interpretations. Therefore, it is prudent

Steady shallow flows past an open channel lateral cavity can induce the excitation of an eigenmode of a gravity standing wave inside the cavity, called seiche, which may be coupled with the shedding of vortices at the opening of the cavity. The presence of the seiche is of fundamental interest as it enhances the mass exchange between the main channel and the cavity. Measurements of the time evolution

Accurate prediction of flood inundation processes in urban areas is challenging, due to the complexity of street layouts and the variety of infrastructures. In this study, based on a laboratory model of urban flooding with a sewer system underneath, a series of laboratory experiments were conducted to investigate the influences of different street layouts and infrastructures on flood inundation processes

We present two statistical models for downscaling flood hazard indicators derived from upscaled shallow water simulations. These downscaling models are based on the decomposition of hazard indicators into linear combinations of spatial patterns obtained from a Principal Component Analysis (PCA). Artificial Neural Networks (ANNs) are used to model the relationship between low resolution (LR) and high

The coefficient of the Brutsaert-Nieber equation cannot provide information on streamflow dynamics independently because its value depends on the exponent. One way to address this challenge is to compute the coefficient after fixing the exponent, which may involve fitting errors. A recent study has therefore adopted a method to decorrelate the coefficient from the exponent. Here, I argue that the decorrelation

Fine-scale discrete fracture simulations provide a natural means to quantify the matrix-fracture fluxes and to specify reference solutions for upscaling approaches such as dual porosity/dual permeability models. Since typically the fine-scale simulations are computationally demanding, and the fractured reservoirs are highly heterogeneous, it is desirable to parametrize the fracture geometry and to

Climate change is expected to significantly alter river hydrological regimes throughout the world, affecting water resources and the frequency of floods and droughts. The objectives of this study were to determine the impacts of climate change and sea level rise on streamflow and floodplain inundation in the subtropical Logan-Albert catchment, Australia. An ensemble of 11 high-resolution climate models

Virtual water flows are used to determine the indirect water requirements of a region or product, making them an indispensable tool for water sustainability analysis and assessment. Commodity flows are a key data needed to compute virtual water but are typically available every 5 years in the United States (US). The lack of continuous, annual commodity flow data severely limits our ability to study

We study the spatial structure of soil moisture fields within savanna ecosystems, whose persistence is vital because it is the driver of the entire ecological structure and function. These include changes in the physical and biogeochemical conditions of the landscape, affecting vegetation state, soil composition, water fluxes, and solar radiation. We focus on computations of the probabilistic structure

Data assimilation techniques are widely used in hydrology and water resources management to improve model forecast uncertainty by assimilating observations. The big challenge in practical applications is how to describe model uncertainties correctly to avoid the occurrence of spurious covariance during data assimilation. In this study, the ensemble square root filter (EnSRF) is used to estimate parameters

To consider the non-Darcian nature of groundwater flow and the permeability reduction owing to well and aquifer clogging, an Izbash's law-based analytical model with a time-dependent hydraulic conductivity function is proposed for constant-rate recharge and constant-head recharge. By means of linearization approximations, variable substitutions and the Laplace transform, approximate analytical solutions

Natural hydrogeological settings may delineate wedge-shaped aquifers that are sandwiched between streams, lakes or sea water bodies along arbitrary-oriented boundary lines. This is the case in multiple river basins, river deltas, alluvial fans, and coastal promontories and heterogeneity patterns are likely to arise because of sedimentation zoning. The aim of present study is to provide a steady-state

There are increasing evidences that probability distributions and associated statistical moments of a variety of hydrogeological and soil science variables and their spatial increments display distinctive scale-dependent features that are not captured by a typical Gaussian model. A Generalized Sub-Gaussian (GSG) model is able to capture key aspects of this pattern. We present the results of a suite

Low-flow estimation at ungagged sites is a challenging task. Ensemble-based machine learning regression has recently been utilized in modeling hydrologic phenomena and showed improved performance compared to classical regional regression approaches. Ensemble modeling mainly revolves around developing a proper training framework of the individual learners and combiners. An ensemble framework is proposed

Understanding fluid flow in complex fractured porous media requires an accurate representation of the pore space, especially in the presence of both granular pores and fractures, which significantly differ in their geometries. The effect of such a complex fluid pathway is prominent in fractured sandstones and carbonates, which store a significant amount of energy resources. Digital core analysis allows

Water shortages pose significant threats to local water security and food production around the world. Water managers have resorted to various water resources planning measures to overcome these challenges. For the first time and for a case study in Iran, we provide a comparative analysis of two such measures: physical and virtual inter-basin water transfers (IBWT). We evaluate green and blue water

In this paper, we identify cropping pattern as a major policy variable. A framework for the generation of alternative cropping patterns (ACPs) in arid regions, called ACPAR, is developed for assessing water and food security. ACPAR is applied to the case study of Egypt, for which a simulation-based national water, food, and trade (NWFT) model exists. ACPAR is formulated to minimize the agricultural

Quasi-steady gravity currents propagating first on a horizontal and then up a sloping boundary are investigated by means of theoretical analysis and laboratory experiments. The bottom slope ranged from 0.18 to 1 and full- and partial-depth configurations were considered. The developed theoretical model, using the depth averaged momentum equation, provides new physical insight into the importance of

Conventional macroscale two-phase flow equations for porous media (such as Darcy's law and Richards Equation) require a constitutive relation for capillary pressure (Pc). The capillary pressure relation significantly impacts the behavior and prediction of fluid flow in porous media, and needs to accurately characterize the capillary forces. In a typical laboratory experiment, a functional macroscopic

Flow in fractured porous media occurs in the earth’s subsurface, in biological tissues, and in man-made materials. Fractures have a dominating influence on flow processes, and the last decade has seen an extensive development of models and numerical methods that explicitly account for their presence. To support these developments, four benchmark cases for single-phase flow in three-dimensional fractured

Identifying key driving forces for streamflow variation is essential for improving sustainable water resource management in terms of understanding how changes in the watershed translate to changes in streamflow. In this study, the relationships between trends in total annual streamflow and trends in watershed characteristics across the contiguous U.S. during 1981-2016 are investigated with data from

The momentum transfer across fluid interfaces in multi-phase flow leads to a non-negligible viscous coupling effect. In this study, we use the lattice Boltzmann method (LBM) as a direct simulator to solve the three-phase flow at pore scale. The viscous coupling effects are investigated for various fluid configurations in simple pore geometries with different conditions in terms of saturation, wettability

The impact of tunnel drainage on local water resources has attracted increasing attention in the past decades. The potential impacts of tunnel drainage on terrestrial vegetation have been evaluated from a groundwater environment perspective. However, previous attempts did not consider the atmospheric and climatic conditions along with the change to the regional groundwater table. To address the lack

Several approaches are commonly applied to modeling fractured aquifers, including stochastic continuum (SC) and discrete fracture network (DFN) models. While DFN models provide a more realistic representation of the system, their development necessitates an accurate characterization of the fracture network. Extensive, and often prohibitive, resources are typically required to map a reliable fracture

This article shows how to consistently and accurately manage the Lagrangian formulation of chemical reaction equations coupled with the superficial velocity formalism introduced in the late 80s by Quintard and Whitaker. Lagrangian methods prove very helpful in problems in which transport effects are strong or dominant, but they need to be periodically put back in a regular lattice, a process called

In this paper, laminar flow through and over models of porous media is studied to characterize the flow at the onset of inertia. Horizontal, vertical or mesh arrays of circular rods are used to model the porous medium. The rods are arranged to cover solid volume fraction ranging from 0.03 to 0.49, and to fill approximately three-quarters of the depth of the test section. Each of the porous media models

Fractures in geological formations constitute high-conductivity conduits which potentially act as preferential paths during fluid injection in soil remediation and reservoir engineering operations. Recently, the measurement of the pressure drop under different flow rates during the flow of yield stress fluids in porous media has been proposed as the basis for an environmentally friendly method to characterize

An original nonlinear multi-dimensional model for the inertial fluid flow through a fluid-porous interface is derived by asymptotic theory for arbitrary flow directions. The interfacial region between the pure fluid and the homogeneous porous region is viewed as a thin transition porous layer characterized by smoothly evolving heterogeneities. The asymptotic analysis applied to the homogenized Navier-Stokes

Using micro-CT imaging and differential pressure measurements, we design a comparative study in which we simultaneously measure relative permeability and capillary pressure on the same reservoir sandstone sample under water-wet and mixed-wet conditions during steady-state waterflooding experiments. This allows us to isolate the impact of wettability on a pore-by-pore basis and its effect on the macroscopic

Multiphase flow in porous media is found in a variety of engineering problems, including in technologies focused on satisfying the energy needs of an expanding global population while minimizing the effects of human activity on climate change. The objective of this study is to provide a better understanding of the importance and interdependence of the wettability-altered fraction, the degree of wettability

Catalytic membranes can degrade gaseous pollutants to clean gas via a catalytic reaction to achieve green emissions. Further, a catalytic membrane is a three scale porous medium. Membranes used in catalytic filters usually have thicknesses of centimeters or millimeters, and consist of active (washcoat) particles, inert material and microscale, micron size, pores. The washcoat particles are porous material

In recent years, several approaches in the field of pollution source identification have been developed to identify the unknown pollution source parameters (PSP) of a river pollution incident. These approaches rely on monitoring data which have to be collected in the case of the pollution incident. Up until now, the influence of the often arbitrarily selected monitoring data on the identification results

We upscale reactive mixing using effective dispersion coefficients to capture the combined effect of pore-scale heterogeneity and molecular diffusion on the evolution of the mixing interface between two initially segregated dissolved species. Effective dispersion coefficients are defined in terms of the average spatial variance of the solute distribution evolving from a pointlike injection, that is

We study the upscaling of pore-scale transport of passive solute in a carbonate rock sample. It is characterized by microporous regions displaying heterogeneous porosity distribution that are accessible due to diffusion only, and a strongly heterogeneous mobile pore space, characterized by a broad distribution of flow velocities. We observe breakthrough curves that are characterized by strong tailing

The intent of this paper is to provide both an introduction to the concepts of information theory, and to review how such concepts might be effectively applied in computing information reduction via upscaling methods. The concept of using scaling postulates to reduce the dimensionality or amount of information in a problem is a central idea in upscaling. In this paper, we present a number of introductory

This study characterized and modeled heterogeneous surface wettability in sandstone and investigated the role of spatial heterogeneity and correlation length of surface wettability on relative permeability in a supercritical CO2 (scCO2)-brine-rock system. Understanding the role of wettability heterogeneity on relative permeability is essential to geological CO2 sequestration, oil and gas recovery,

The Smoothed Particle Hydrodynamics (SPH) method is used in this paper to simulate the transport process of coastal pollutant by solving the two-dimensional (2D) depth averaged advection-diffusion equation in Lagrangian framework. To avoid directly discretizing the second-order derivatives, the diffusion terms are decomposed into two first-order derivatives by introducing the diffusive flux. To verify

Pore-network representations of permeable media provide the framework for explicit simulation of capillary-driven immiscible displacement governed by invasion-percolation theory. The most demanding task of a pore-network flow simulation is the identification of trapped defending phase clusters at every displacement step, i.e. the phase connectivity problem. Instead of employing the conventional adjacency

Despite a longstanding interest in understanding the effects of rock fragments on soil hydraulic properties, physically-based models to describe the effective hydraulic conductivity of stony soils are still rare. The conductivity of stony soils is mostly described by simple scaling approaches, assuming impermeable rock fragments. We present a model based on the general effective medium (GEM) theory

This study presents the development, refinement, and application of a 3-D multiphase flow model for the simulation of tsunami propagation on land and its hydrodynamic force on a coastal building. The model is based on the Volume/Surface Integrated Average-based Multi-Moment Method (VSIAM3) with improved accuracy by adopting the temporary moment (TM) method to update the non-normal flow variables. A

Anthropogenic climate change has led to nonstationarity in hydrological data and their statistical characteristics. To consider nonstationarity in regional frequency analysis, several nonstationary index flood (NS-IF) methods comprising a time-dependent site-specific scaling factor or nonstationary regional growth curves have been suggested. However, these methods have limitations related to underestimation

Reservoirs have been widely used to regulate streamflow to meet both human and natural water requirements. This study applies a hidden Markov-decision tree (HM-DT) model to derive representative reservoir operation modules under various operation conditions (i.e., inflow, storage, as well as unknown factors) and their transitions (the dynamic change of operation rules) that reflect the impacts of seasonality

We use Approximate Bayesian Computation and the Kullback–Leibler divergence measure to quantify to what extent horizontal and vertical equivalent electrical conductivity time-series observed during tracer tests constrain the 2-D geostatistical parameters of multivariate Gaussian log-hydraulic conductivity fields. Considering a perfect and known relationship between salinity and electrical conductivity

Michaelis–Menten kinetics describe a broad range of physical, chemical, and biological processes. Since they are non-linear, spatial averaging of reaction kinetics is non-trivial, and it is not known how concentration gradients affect the global effective kinetics. Here, we use numerical simulations and theoretical developments to investigate the effective kinetics of diffusing solute pulses locally