For simulating reactive transport on aquifer‐scale, various modeling approaches have been proposed. They vary considerably in their computational demands and in the amount of data needed for their calibration. Typically, the more complex a model is, the more data are required to sufficiently constrain its parameters. In this study, we assess a set of five models that simulate aerobic respiration and

Recent advances in remote sensing and the upcoming launch of the joint NASA/CNES/CSA/UKSA Surface Water and Ocean Topography (SWOT) satellite point towards improved river discharge estimates in ungauged basins. Existing discharge methods rely on ‘prior river knowledge’ to infer parameters not directly measured from space. Here, we show that discharge estimation is improved by classifying and parameterizing

The spatiotemporal dynamics of plant water sources are hidden and poorly understood. We document water source use of Quercus garryana growing in Northern California on a profile of ca. 50 cm of soil underlain by 2‐4 m of weathered bedrock (sheared shale mélange) that completely saturates in winter, when the oaks lack leaves, and progressively dries over the summer. We determined oak water sources by

Effective monitoring of groundwater withdrawals is necessary to help mitigate the negative impacts of aquifer depletion. In this study, we develop a holistic approach that combines water balance components with a machine learning model to estimate groundwater withdrawals. We use both multi‐temporal satellite and modeled data from sensors that measure different components of the water balance and land

Ensemble smoother (ES) has been widely used in various research fields to reduce the uncertainty of the system‐of‐interest. However, the commonly‐adopted ES method that employs the Kalman formula, that is, ES(K), does not perform well when the probability distributions involved are non‐Gaussian. To address this issue, we suggest to use deep learning (DL) to derive an alternative analysis scheme for

eliable accounting of agricultural water use is critical for sustainable water management. However, the majority of agricultural water use is not monitored, with limited metering of irrigation despite increasing pressure on both groundwater and surface water resources in many agricultural regions worldwide. Satellite remote sensing has been proposed as a low‐cost and scalable solution to fill widespread

Immiscible two‐phase flow through porous materials exhibits different invasion patterns controlled by dynamic conditions, competition between the viscous and capillary forces and the contrast between the fluids viscosities. Two distinct invasion patterns are viscous and capillary fingering. While the first one happens under unfavorable viscosity ratios at high injection rates, the second one happens

Time‐variable transit time distributions (TTDs) have been utilized as a tool to understand how catchments transmit water. However, most of the existing TTD estimation methods require to impose certain structures on those TTDs a priori, which could lead to misinterpreting data. We present a data‐based method to estimate time‐variable TTDs without imposing their structure a priori. The core of the method

This paper proposes a multistage method for burst leak localization through valve operations (VOs) and smart demand metering in district meter areas (DMAs) of water distribution systems (WDSs). Each stage includes partitioning of the DMA into two subregions using VOs and identification of potentially leaking pipes within the subregions through water balance analysis based on smart demand meters. Such

Clay minerals are abundant in shale, characterized by a lamellar structure and dimensions smaller than a micron, giving rise to nanometer‐scale pore sizes and large specific surface area. They are commonly associated with water. However, the spatial distribution of the unsaturated water in clay is not very well understood, which significantly affects the subsequent shale gas flow capacity. Wettability

The question of how much longer groundwater can support large‐scale agricultural production is one of global significance. Many of the world's regional aquifers supporting irrigated agriculture are on a trajectory toward resource depletion. In the absence of alternative water supplies, the only viable near‐term (few to several decades) option for redirecting these heavily stressed systems on to more

Across the world, cities are spending billions of dollars to manage urban runoff through decentralized green infrastructure (GI). This research uses an agent‐based model to explore some of the physical, social, and economic consequences of one such urban GI programs. Using the Bronx, NY, as a case study, two alternative approaches to GI application are compared. The first (Model 1) mimics NYC’s current

Using natural tracer profiles to study migration of porewater salinity can help determine fluid fluxes and the timescales of salinization and freshening in coastal regions. Saline groundwater associated with evaporation and transgression events is widely distributed in the North China Plain (NCP). However, the fluid flux, time scales and importance of different salinization processes are poorly constrained

The evolution of heterogeneous and anisotropic media in the uniform dissolution regime (low Damkӧhler number), is studied here using a numerical network model. The uniform dissolution extensively homogenizes the medium and therefore the flow field. The homogenization is further enhanced when the surface reaction is transport‐controlled—when slow diffusion of dissolved ions away from the mineral surface

Exploring water fluxes between hydrological model (HM) components is essential to assess and improve model realism. Many classical metrics for HM diagnosis rely solely on streamflow and hence provide limited insights into model performance across processes. This study applies an information theory measure known as “transfer entropy” (TE) to systematically quantify the transfer of information among

Widespread flooding can cause major damages and substantial recovery costs. Still, estimates of how susceptible a region is to widespread flooding are largely missing mainly because of the sparseness of widespread flood events in records. The aim of this study is to assess the seasonal susceptibility of regions in the United States to widespread flooding using a stochastic streamflow generator, which

Recent studies have indicated that under certain conditions, most soils are water repellent to some degree, which impacts agricultural fields, pastures, forests, grasslands, and turf areas. Soil water repellency originates from amphiphilic molecules that reorient during contact with water. However, models to describe the flow in soils affected by time‐dependent contact angle (CA(t)) are still lacking

One of the important mechanisms in CO2 storage is dissolution trapping. The dissolution of CO2 in aquifer brines increases the brine density and leads to hydrodynamic instabilities, formation of CO2‐rich fingers, and a desirable acceleration of the CO2 dissolution. In recent decades, there has been an intensive effort to identify suitable deep aquifers for CO2 sequestration. Despite reports that background

Cyclone Mekunu hit the southern Arabian Peninsula in late May 2018 and brought rainfall amounts that accounted for up to six times the mean annual precipitation. Coming from the Arabian Sea, a quite underdocumented region with regard to cyclones, the storm eye crossed the Omani coast approx. 80 km east of the border to Yemen. Using automatic samplers, rainfall samples were collected during the event

The streamflow drought hazard can be characterized in a variety of ways, including using different indices. Traditionally, percentile‐based indices, such as Q95 (the flow exceeded 95% of time), have been used by the hydrological community. Recently, the use of anomaly indices such as the Standardized Streamflow Index (SSI), a probability index‐based approach adopted from the climatological community

Soil water wettability or water repellency is a phenomenon that can affect infiltration and, ultimately, runoff. Thus, there is a need to develop a model that can quantitatively capture the influence of water repellency on infiltration in a physically meaningful way and within the framework of existing infiltration theory. The analytical model developed in this study relates soil sorptivity (an infiltration

Thermohaline convection (THC) in porous media is frequently investigated using the problem of porous enclosure. Most of the existing modeling‐based studies are limited to 2D simulations, because 2D assumption is widely used to deal with computational requirement of 3D numerical solutions. Analytical solutions serve as an alternative to deal with computational requirement of numerical solutions. Existing

Three‐dimensional, multiphase simulations are used to analyze migration of methane leakage from a hydrocarbon wellbore. The objective is to evaluate the relevance and importance of coupling fast, advective transport of methane through fractures with slower, diffusive transport in the shale matrix below a freshwater aquifer on water quality assuming dual‐domain mass transfer (DDMT) in the reservoir

Both theory and application of multispecies reactive transport for in situ groundwater bioremediation involving a vertical circulation well (VCW) are not fully understood despite its importance and common usage in aquifer remediation practices. This study proposes novel approaches including two methods for design and remediation prediction of a VCW system, which involves multispecies, multiphase and

Over the central United States, a large fraction of heavy precipitation and flood events have been tied to atmospheric rivers (ARs) and to two large‐scale atmospheric modes, the Pacific–North American teleconnection pattern (PNA) and the Arctic Oscillation (AO). Here, we build on these insights to model the frequency of heavy precipitation events at 88 locations across the central United States. We

Despite a multitude of small catchment studies, we lack a deep understanding of how variations in critical zone architecture lead to variations in hydrologic states and fluxes. This study characterizes hydrologic dynamics of fifteen catchments of the US Critical Zone Observatory (CZO) Network where we hypothesized that our understanding of subsurface structure would illuminate patterns of hydrologic

Accurate understanding of diffusion of anionic radionuclides in different clays is significant to predict long‐term performance of high‐level radioactive waste (HLW) repositories. The importance of electrical double layer (EDL) on anionic tracer diffusion in different clays has been studied by both through‐diffusion experiments and pore‐scale simulations in this work. The through‐diffusion experiments

Bedload transport in natural channels typically shows large fluctuations even for constant hydraulic forcing. It has been shown that the threshold shear stress for initiation of motion depends for example on the bed morphology and on channel slope, and that it may be influenced by flood history effects. This study is based on a unique dataset of continuous field observations of bedload transport acquired

Estimations of reservoir bathymetry and storage are of great significance due to their substantial impacts on hydrological processes and water resource management. However, existing approaches for reservoir bathymetry construction often rely on field measurements, which restricts their application at regional and global scales. This study proposes a novel Approach for Determining the BAthymetry and

The effect of capillary pressure on multiphase flow is described by the capillary pressure gradient term in the fractional flow equation. This term is typically neglected during core‐flooding experiments, as it is not easily accessible. However, the capillary pressure is not constant during core flooding owing to a capillary pressure discontinuity at the core outlet. By imaging spatial fluid distributions

The accurate representation of the local‐scale variability of precipitation plays an important role in understanding the hydrological cycle and land‐atmosphere interactions in the High Mountain Asia region. Therefore, the development of hyper‐resolution precipitation data is of urgent need. In this study, we propose a statistical framework to downscale the Modern‐Era Retrospective analysis for Research

The dry end of the soil water retention curve (WRC) plays an important role in various hydrologic, solute transport, plant, and microbial processes. Despite increasing application of biochar as a soil amendment, knowledge about water retention in biochars and biochar‐amended soils under dry conditions is lacking. Mechanistic models are presented to predict the WRC for biochars and biochar‐amended soils

In order to advance the use of the cosmic‐ray neutrons (CRNs) to map soil moisture in heterogeneous landscapes, we need to develop a methodology that reliably estimates soil moisture without having to collect 100+ soil samples for each point along the survey route. In this study, such an approach is developed using physically‐based modeling with the numerical MCNP neutron transport code. The objective

Wetlands provide valuable hydrological, ecological, and biogeochemical functions, both alone and in combination with other elements comprising the wetlandscape. Understanding the processes and mechanisms that drive wetlandscape functions, as well as their sensitivity to natural and man‐made alterations, requires a sound physical understanding of wetland hydrodynamics. Here, we develop and apply a single

Identifying fluid flow maldistribution in planar geometries is a well‐established problem in subsurface science/engineering. Of particular importance to the thermal performance of Enhanced (or “Engineered”) Geothermal Systems (EGS) is identifying the existence of non‐uniform (i.e., heterogeneous) permeability and subsequently predicting advective heat transfer. Here, machine learning via a Genetic

Evaporation is the phenomenon by which a substance is converted from its liquid into its vapor phase, independently of where it lies in nature. However, language is alive, and just like regular speech, scientific terminology changes. Frequently those changes are grounded on a solid rationale; but sometimes these semantic transitions have a fragile foundation. That is the case with 'evapotranspiration'

The passage of a tropical storm, as the main driver of storm surge and high waves in many coastal regions, can also generate heavy rainfall and cause river overflow. The resulting combination of riverine, pluvial, and coastal flood hazard can result in catastrophic losses particularly in densely populated coastal environments. In this study, we characterize compound flooding caused by Tropical Storm

The rainfall rate is a crucial variable in modeling runoff and water erosion. Rainfall rates present a very large spatial and temporal variability. Radars are used to estimate the spatial and temporal changes in rainfall rates during storms. The radar reflectivity is strongly affected by the drop size distribution (DSD) that results from the relative intensity of the microphysical processes involved

Arsenic (As) and antimony (Sb) speciation and mobility in river systems can be influenced by the redox conditions of benthic and hyporheic zone sediments. However, our understanding of how temperature fluctuations influence riverine As and Sb mobility over diel and seasonal time frames, via moderation of sediment redox conditions, is poorly constrained. Here we compare diel and seasonal water quality

Water resources systems models enable valuable inferences on consequential system stressors by representing both the geophysical processes determining the movement of water and the human elements distributing it to its various competing uses. This study contributes a diagnostic evaluation framework that pairs exploratory modeling with global sensitivity analysis to enhance our ability to make inferences

Reach‐scale at‐a‐station hydraulic geometry (AHG) relationships are power laws that describe variations of reach‐averaged water depth, wetted width, and current velocity in stream reaches when discharge varies. Modeling AHG exponents is important, because the variations of hydraulics with discharge in stream networks influence physical habitats of aquatic species, biodiversity, water temperature, nutrient

Assessing the risks associated with transport of contaminants in hydrogeological systems requires the characterization of multiple sources of uncertainty. This paper examines the impact of the uncertainty in the source zone mass release rate, aquifer recharge, and the spatial structure of the hydraulic conductivity on transport predictions. Through the use of the Lagrangian framework, we develop semianalytical

Mountain block systems are critical to water resources and have been heavily studied and modeled in recent decades. However, due to lack of field data, there is little consistency in how models represent the mountain block subsurface. While there is a large body of research on subsurface heterogeneity, few studies have evaluated the effect that common conceptual choices modelers make in mountainous

Whereas current erosion models are successful in quantitative estimates of soil erosion by water flow, modeling the coevolution of geomorphological features, particularly rill network properties and soil erosion on hillslopes, is still a major challenge. In this study, we propose a rill evolution modeling approach and combine it with a rainfall‐runoff and soil erosion model to simulate the feedback

Watersheds aggregate precipitation signals of many intensities and from many locations into a single observable streamflow at an outlet point. This dependency between precipitation and streamflow varies seasonally and can shift over time due to changes in land cover, climate, human water uses, or changes in properties of precipitation events themselves. We apply information theory‐based measures to

Despite a multitude of models predicting sediment transport dynamics in open‐channel flow, self‐organized vertical density stratification that dampens flow turbulence due to the interaction between fluid and sediment, has not been robustly validated with field observations from natural rivers. Turbulence‐suppressing density stratification can develop in channels with low channel‐bed slope and high

Karstified carbonate aquifers are highly heterogeneous systems characterised by multiple recharge, flow and discharge components. The quantification of the relative contribution of these components, as well as their numerical representation, remains a challenge. This paper identifies three recharge components in the time and frequency domain. While the analysis in the time domain follows traditional

Heat transport in natural porous media, such as aquifers or streambeds, is generally modeled assuming local thermal equilibrium (LTE) between the fluid and solid phases. Yet, the mathematical and hydrogeological conditions and implications of this simplification have not been fully established for natural porous media. To quantify the occurrence and effects of local thermal disequilibrium during heat

Reuse of wastewater through a combination of advanced water treatment (AWT) and managed aquifer recharge (MAR) is an important water management option. As an integral part of any AWT‐MAR system, the geochemical compatibility of the recharged water with the targeted aquifer must be assessed to avoid groundwater quality deterioration. Although short‐term field experiments may uncover potentially concerning

Groundwater discharge zones connect aquifers to surface water, generating baseflow and serving as ecosystem control points across aquatic ecosystems. The influence of groundwater discharge on surface flow connectivity, fate and transport of contaminants and nutrients, and thermal habitat depends strongly on hydrologic characteristics such as the spatial distribution, age, and depth of source groundwater

Stream hydromorphology regulates in‐stream water flow and interstitial flow of water within streambed sediments, the latter known as hyporheic exchange. Whereas hyporheic flow has been studied in sand‐bedded streams with ripples and dunes and in gravel‐bedded streams with pool‐riffle morphology, little is known about its characteristics in plane bed morphology with subdued streambed undulations and

The main goal of this study is to explore whether the ideas established by surface water hydrologists in the context of predictions in ungauged basins can be useful in hydrogeology. The concrete question is whether it is possible to create predictive models for groundwater systems with no or few observations based on knowledge derived from similar groundwater systems which are well observed. To do

Excessive nitrate threatens a wide range of water resources, aquatic habitats, and sensitive infrastructure. Despite this problem, tracing a nutrient from its eventual fate back to its origin remains an elusive challenge due to heterogeneity in how nutrient sources and hydrologic pathways are connected. Typically, this problem is underdetermined (i.e., too many unknowns, not enough equations) and cannot

Nested groundwater flow systems (NGFS) are commonplace in various hydrogeological environments, including endorheic basins and coastal aquifers. The subsystems of the NGFS can be spatially separated by streamlines around the internal stagnation points. At the discharge zones of the topographic depressions, saline water often emerges due to high evaporation in endorheic drainage basins or the combined

Efficiently measuring groundwater flow in bedrock aquifers is inherently challenging due to the irregular distribution and fine scale of fractures. Recent advances in Active Distributed Temperature Sensing (A‐DTS) in boreholes temporarily sealed with liners have made it possible to quantify flow rates in such aquifers at many different depths using heat as a tracer, but until now only data collected

We experimentally and numerically study the influence of gravity and finite‐size effects on the pressure‐saturation relationship in a given porous medium during slow drainage. The effect of gravity is systematically varied by tilting the system relative to the horizontal configuration. The use of a quasi two‐dimensional porous media allows for direct spatial monitoring of the saturation. Exploiting

This study investigated the added value of different data for calibrating a runoff model for small basins. The analysis was performed in the 66 ha Hydrological Open Air Laboratory, in Austria. An Hydrologiska Byråns Vattenbalansavdelning (HBV) type, spatially lumped hydrologic model was parameterized following two approaches. First, the model was calibrated using only runoff data. Second, a step‐by‐step

The rapid expansion of unconventional oil and gas development (UD), made possible by horizontal drilling and hydraulic fracturing, has triggered concerns over groundwater contamination and public health risks. To improve our understanding of the risks posed by UD, we develop a physically based, spatially explicit framework for evaluating groundwater well vulnerability to aqueous phase contaminants

Catchment nutrient export, especially during high flow events, can influence ecological processes in receiving waters by altering nitrogen (N) and phosphorus (P) concentrations and relative amounts (stoichiometry). Event‐scale N and P export dynamics may be significantly altered by land use/land cover (LULC) and season. Consequently, to manage water resources, it is important to understand how LULC

Soil salinity and sodicity are serious environmental hazards, with the potential to limit agricultural production and cause destructive soil degradation. These concerns are especially high in dry areas, which often rely on saline and sodic irrigation water to support agriculture. To assess long‐term soil degradation risk, we introduce the Salt of the Earth (SOTE) model, which describes the dynamics