The hyporheic zone provides opportunities for the turnover and removal of nutrients such as ammonium and nitrate from stream water. Hyporheic flow patterns and dynamics govern the transport of nutrients and other solutes through the hyporheic zone and in turn control their transformation and removal. To better understand the links between flow and turnover, we systematically studied nutrient turnover

Determining the effective permeability (keff) of geological formations has broad applications to site remediation, aquifer discharge or recharge, hydrocarbon production, and enhanced oil recovery. The objectives of this study are: (1) to explore an approach to estimating keff at the reservoir scale using the critical path analysis (CPA), (2) to evaluate the accuracy of this new approach by comparing

The regionalised characteristics of a sub-basin's long-term hydrological behaviour are used as multiple constraint filters for constraining hydrological model simulations in the Congo Basin using the monthly time step Pitman model. The results suggest that the constraints are appropriate in many sub-basins (≥ 20 gauging stations), but not all. Detailed examination of these results suggested that the

The propagation of tides and riverine floodwater in coastal wetlands is controlled by subtle topographic differences and a thick vegetation canopy. High-resolution numerical models have been used in recent years to simulate fluxes across wetlands. However, these models are based on sparse field data that can lead to unreliable results. Here, we utilize high spatial-resolution, rapid repeat interferometric

We present a new Image Velocimetry (IV) hybrid that estimates vector fields from images with widely different visualization pattern sizes such as those encountered in riverine bedform migration. The IV approach is obtained by complementing the Cross-correlation Method (CCM) with algorithms of Optical Flow Methods (OFM). The OFM procedures are first applied to automatically determine the optimal Search

Release of colloids and their subsequent transport into the subsurface environments takes place during a wide range of applications such as industrial, energy storage, and agricultural activities. Therefore, processes contributing to transport, attachment, and re-mobilization of colloids in porous media are attracting attention. A fraction of the released colloids may cross the soil vadose zone to

Extreme precipitation of multiple durations is responsible for major natural hazards in mountainous regions, such as flash floods and debris flows. Understanding the orographic impact on the statistics of precipitation extremes is therefore crucial for improving hydrological design and risk management strategies. Here, we use a novel statistical approach for the analysis of extremes based on ordinary

Modeling variable-density flow in unconfined aquifers is a challenging task because of the nonlinear coupling between variably saturated flow and contaminant transport. This results in a highly nonlinear system since the strongly nonlinear Richards flow equation is, in addition, coupled to the advection-dispersion transport equation by viscosity and density variation. The solution of such a nonlinear

Elevation-based hydrogeomorphic models are widely used to parsimoniously delineate floodplains with limited input data using topographic gradients to distinguish floodplain areas from hillslopes. Hydrogeomorphic models generally use scaling laws to assess flood flow depths as a function of contributing drainage areas. Floodplains are consequently mapped as those areas underlying maximum flood levels

We present a splitting method for the one-dimensional Saint-Venant-Exner equations used for describing the bed evolution in shallow water systems. We adapt the flux vector splitting approach of Toro and Vázquez-Cendón (2012) and identify one subsystem of conservative equations (advection system) and one of non-conservative equations (pressure system), both having a very simple eigenstructure compared

Since conventional in situ measurements of suspended sediments in the river system are labor-intensive and time-consuming, remote sensing approaches using multi- or hyper-spectral cameras have widely been applied to obtain high-resolution suspended sediment concentration (SSC) distributions in rivers and streams. However, in nature, the properties of heterogeneous sediment, such as the mineral content

CO2 injection into deep saline aquifers has shown to be a feasible option, as for their large storage capacity under safe operational conditions. Previous studies have revealed that CO2 can be trapped in the subsurface by several mechanisms. Despite the major advances in studying these trapping mechanisms, their dynamic interactions in different periods of a full-cycle process have not been well understood;

Differences in the boundary condition near buried corrugated pipes used for combined drainage and irrigation show that the hydraulic resistance due to perforations are not identical under both drainage and subsurface irrigation modes. No studies to date have sufficiently examined how perforation characteristics such as size and configuration affect the exit head loss of buried corrugated pipes used

Peak discharge to drainage area relationships are widely applied engineering solutions for design flood estimation in ungauged basins. In this study we investigated the effects of antecedent moisture conditions (AMC), rainfall duration, and channel transmission losses on discharge-drainage area power law scaling relationships. The spatial organization of peak discharges were evaluated through coupled

Effective water resources management in California relies substantially on real-time information of snow water equivalent (SWE) at basin and mountain range scales as mountain snowpacks provide the primary water supply for the State. However, SWE estimation based solely on remote sensing, modeling, or ground observations alone does not meet contemporary operational requirements. This study develops

Management and planning of water resource systems face great challenges under climate change. Because the magnitude of climate change is highly uncertain, the robustness (i.e., ability to perform satisfactorily over a wide range of possible climate conditions) should be evaluated for water resource systems. However, for climate-informed robustness-based methods, the effects of climate model credibility

Hydrodynamic modeling is a common approach for flood inundation mapping. These models use conservation of mass and momentum to simulate the river hydrodynamics during flood events. To simulate floods and estimate the spatio-temporal distribution of extreme water levels, the upstream and downstream flows are used as the minimum required boundary conditions (BCs) in a hydrodynamic model. In this study

Integrated surface–subsurface hydrological models (ISSHMs) are increasingly being used for the assessment of contaminant transport in the environment, in addition to their more common use in water flow applications. However, the subsurface solute transport solvers in these models are prone to numerical dispersion errors. Numerical dispersion is a well-known issue in groundwater modeling, but its impacts

Near-miscible supercritical CO2 (scCO2) injection and its underlying pore-scale physics were experimentally investigated in an oil-wet carbonate rock at elevated temperature and pressure conditions using X-ray microtomography. The results of in situ contact angle measurements yielded direct evidence showing that the scCO2 injection triggered a wettability reversal process resulting in reduced oil-wetness

The numerical modelling of ionic diffusive transport through a charged thin film of electrolyte is mathematically and computationally complex due to the strongly coupled hydrodynamics and electrochemical interactions. Generally, simulations are performed by solving the Poisson equation together with the Nernst-Planck flux formula to model electrochemical processes in electro-diffusion problems. One

The objective of this paper is to investigate the interplay between wettability alteration and domain geometry in influencing the pore-scale displacement and trapping mechanisms of two-phase flow in porous media. A new wettability alteration algorithm is introduced to quantify and track the spatial and temporal variability of the wettability state of every pore. Simulations in an initially oil-wet

Identification of the location and strength of a contaminant source in an aquifer is a challenging but crucial task. Efficient surrogate models can be constructed to replace traditional time-consuming simulators while solving this inverse problem. In recent years, with the rapid development of machine learning (ML) algorithms, the artificial neural network (ANN) has been proven to be an efficient way

Spontaneous imbibition profiles are widely used for wettability evaluation of porous media such as rocks. However, mostly the equilibrium imbibed volume is the basis for wettability evaluation. Here, we model the relationship between the shape of imbibition profile and wettability of a medium. We develop a wettability evaluation criterion based on the change in Helmholtz free energy of the system during

Fracture surface topography exhibits long-range spatial correlations resulting in a heterogeneous aperture field. This leads to the formation, within fracture planes, of preferential flow channels controlling flow and transport processes. By means of a 3-D heat transport model coupled with a 2-D fracture flow model based on the lubrification approximation (i.e., local cubic law), we investigate how

When a smoothed particle hydrodynamics (SPH) method, a Lagrangian and meshfree numerical scheme, is used to solve the advection-dispersion equation (ADE), SPH solutions may not be accurate when particles are irregularly distributed, i.e., the distance between two neighbor particles varies irregularly in a simulation domain. Particle irregularity may be caused by nonuniform groundwater flow in a heterogeneous

This study examines multi-scale aspects of radar-rainfall (R-R) conditional error, defined as the difference between a given R-R value and the conditional average of corresponding reference observations. To decompose the systematic and random error components, the authors adopted the second-order separation method while previous studies relied on addressing the first-order moment (i.e., conditional

Multiphase flow simulation is well-known to be computationally demanding, and modeling large-scale engineered subsurface systems entails significant additional numerical challenges. These challenges arise from: (a) the presence of small-scale discrete features like shafts, tunnels, waste packages, and barriers; (b) the need to accurately represent both the waste form processes at the small spatial

The migration of active particles in a laminar open-channel flow is significant for many ecological and biological processes associated with ambient water, for example, the harmful algae blooms in the long-distance water conveyance project. This paper presents an analytical analysis of the migration of the buoyancy-controlled active particles in a laminar open-channel flow. The analytical solution

Despite the existence of several stochastic streamflow generators, not much attention has been given to representing the impacts of large-scale climate indices on seasonal to interannual streamflow variability. By merging a formal predictor selection scheme with vine copulas, we propose a generic approach to explicitly incorporate large-scale climate indices in ensemble streamflow generation at single

Accurate simulation of flow behaviors in fractured porous media is challenging. We present a discontinuous Galerkin (DG) approximation and continuous Galerkin (CG) approximation for compressible single- and two-phase flow in porous media with conducting (high permeable) and blocking (low permeable) fractures using a mixed-dimensional approach in which the fracture is described as a reduced-dimensional

Small-scale bed form topographies control hyporheic exchange and biogeochemical processes within aquatic sediments, which ultimately affect water quality and nutrient cycling at the watershed scale. The impact of three-dimensional and small-scale bed form topographies on hyporheic exchange and solute mixing is investigated in the present work. The effect of bed form morphologies on the development

Pumping tests are established for characterizing spatial average properties of aquifers. At the same time, they are promising tools to identify heterogeneity characteristics such as log-conductivity variance and correlation scales. We present the extended Generalized Radial Flow Model (eGRF) which combines the characterization of well flow in fractal geometry with an upscaled conductivity for pumping

We conduct numerical simulations to investigate the role of aperture heterogeneity in early-stage karstification of a fractured carbonate rock. The fracture network is formed by a dominant set of persistent fractures and a secondary set of short fractures that abuts the dominant set. The variable aperture distribution priori to dissolution is derived from geomechanical simulation. We report that the

In this work, the formation of karstic networks is modeled through the phenomenological stochastic differential Langevin equation. The solution of this equation follows through the application of the lattice-gas cellular automata formalism in terms of spatial and temporal discretization. The flow velocity vector is computed using a stochastic dimensionless equation where permeability, porosity, facies

Artificial freshwater recharge is commonly used to mitigate seawater intrusion and restore salinized aquifers in coastal zones. While the temperature of recharged freshwater often differs from that of aquifers, effects of temperature differences on water flow and salinity distributions are rarely examined. Based on laboratory experiments and numerical simulations, we found that the response of salinity

In water resources management and practices, the time-connected duration and frequency of episodic low streamflow events (and droughts) are often needed for a range of purposes such as water supply planning, low flow management, and drought planning. However, the existing graphical tools commonly used in hydrology such as flow duration curves (FDC), discharge-duration-frequency (QdF), and severity-duration-frequency

International transboundary aquifers provide important water supplies to over 150 countries. Long-term sustainability of these aquifers requires transboundary cooperation and yet only a select few (1%) transboundary aquifers are regulated by a treaty. To better understand the incentives that allow treaties to emerge, we develop a two-player game theoretic model that couples groundwater behavior and

Recent droughts in Europe have shown that national water systems are facing increasing challenges when dealing with drought impacts. Especially the Netherlands has seen an increasing need to adapt their water management to improve preparedness for future drought events. Ideally, the necessary information needed for operational water management decisions should be readily available ahead of time and/or

Groundwater flow in an unconfined aquifer can be described by the Boussinesq equation. The Boussinesq equation is nonlinear and approximate solutions exist only for specific flow conditions. In the present work, the nonlinear equation is tackled analytically via a refinement of its linearized solution in a perturbation series framework. The perturbation series solution applies for any time-dependent

This study presents novel exact analytical solutions to a set of simultaneous three-dimensional advection-dispersion equations coupled with a sequential first-order degradation reaction network involving distinct retardation factor values among individual species. The analytical solutions to the coupled partial differential equation system subject to both the first - and third -type inlet source boundary

Salt deposition has been encountered in near-wellbore regions of saline reservoirs during field-scale carbon dioxide (CO2) sequestration. To explain this phenomenon, pore-scale studies, mostly in the form of micromodel visualizations, have been previously implemented. However, there is limited knowledge about salt deposition and inherent dynamics in reservoir rocks. This study investigates and characterizes

Parameter estimation has a high importance in the geosciences. The ensemble Kalman filter (EnKF) allows parameter estimation for large, time-dependent systems. For large systems, the EnKF is applied using small ensembles, which may lead to spurious correlations and, ultimately, to filter divergence. We present a thorough evaluation of the pilot point ensemble Kalman filter (PP-EnKF), a variant of the

In hydrological modelling, traditionally one calibration was performed over a certain calibration period before the model is used to study the hydrological system. This implies that a constant model structure and parameterization are assumed. However, if the catchment system is subject to changes that are not incorporated in the model, the parameter values found in a calibration period may not be optimal

Estimation of CO2 storage capacity in fractured porous reservoirs requires a better understanding of the CO2-water flow fundamentals in fracture-matrix systems. There are few core-flood experiments on three-dimensional CO2-water drainage in a fracture-matrix system, yet none have examined the impacts of the capillary continuity of fractures and fracture-matrix interactions. In this study, twelve drainage

Depth to water table (DWT) for an unconfined aquifer affects a wide range of hydrological, ecological, and agricultural problems such as soil salinization, plant type, and crop output. In nature conditions (without human impacts), DWT in shallow groundwater zones is mainly driven by evapotranspiration and precipitation. In real-world conditions, the human impacts on groundwater hydrological processes

Climate change has a significant impact on the runoff of basins in cold, dry areas. The quantification of regional ecohydrological responses to climate change such as warming and drought is essential for establishing proper water resource management schemes. We propose a simple and novel method based on the Budyko framework to evaluate the hydrologic resilience of 16 basins that conform the Asian Water

We investigate the combined effects of network scale flow variability and retention due to matrix-diffusion on the scaling behavior of transport through fractured media. Two of the principal mechanisms controlling the transport of solutes through fractured low-permeability media are broad distributions of flow velocities and retention times in the solid matrix. We study the relative impact of these

Until recently, wave and hydrodynamic properties in the cross-shore direction have been linked to accretive or erosive morphological evolution. However, various uncertainties remain, hindering the full understanding and accurate prediction of the transport direction and quantity of sediment transport in nearshore areas. In this study, we showed that flash rip currents (FRCs) could significantly amplify

Riemann problems at geometric discontinuities are a classic and fascinating topic of hydraulics. In the present paper, the exact solution to the Riemann problem of the one-dimensional (1-d) Shallow water Equations at monotonic width discontinuities is completely determined for any initial condition. This solution is based on the assumption that the relationship between the states immediately to the

Snow and glaciers are important freshwater resources in the Himalayan catchments for all biological activities. However, under recent climate change, these resources are decreasing, thereby posing a serious threat to the future freshwater resources among the Himalayan catchments. Therefore, understanding the hydrological behaviour and sources of streamflow is necessary for better assessment, planning

An adaptive scheme for the sequential formulation of reactive transport involving two fluid phases is presented. Instead of solving the transport problem on the global fine-scale model, we decompose the domain into coarse gridblocks that are aggregates of fine gridblocks, and we define and solve transport problem on each of the coarse blocks. The details of the prolongation operator that allows for