• Issue

    Water Resources Research: Volume 56, Issue 8

    August 2020

Issue Information

Free Access

Issue Information

  • First Published: 24 August 2020

Research Articles

Free Access

Operational Bayesian GLS Regression for Regional Hydrologic Analyses

  • First Published: 19 February 2020
Key Points

  • A comprehensive statistical framework for regional hydrologic regression is presented with spatially correlated flow data and varying record lengths
  • Framework correctly attributes variability to sampling errors in computed statistic, variability explained by the model, and model error
  • New diagnostics includes Bayesian plausibility value, pseudo adjusted R2, pseudo ANOVA, and Bayesian metrics for leverage and influence

Free Access

Cation Exchange in Groundwater-Chemical Evolution and Prediction of Paleo-Groundwater Flow: A Natural-System Study

  • First Published: 16 April 2020
Key Points

  • Cation compositions of the clay-exchange complex in equilibrium with the groundwater provide information on paleo-flow and composition
  • The equation for calculating Na, Ca, Mg, K, and Sr cation composition of the clay exchange complex in equilibrium with groundwater is provided
  • Cation ratios in the water and on the clay-exchange complex can be used to trace flow and to identify areas of modern contamination

Free Access

CSO Reduction by Integrated Model Predictive Control of Stormwater Inflows: A Simulated Proof of Concept Using Linear Surrogate Models

  • First Published: 26 April 2020
Key Points

  • Integrated model predictive control of stormwater inflows can reduce overflows, almost as much as disconnecting stormwater from the sewers
  • Linearized surrogate models and convex optimization make implementation compatible with the time constraints in an operational setting
  • The performance depends on the prediction horizon and the recursive initialization of the surrogate models with a detailed model

Open Access

The Utility of Information Flow in Formulating Discharge Forecast Models: A Case Study From an Arid Snow-Dominated Catchment

  • First Published: 29 April 2020
Key Points

  • Hydrologic response times and dominant controls on catchment discharge are inferred through information flow
  • Specialized neural networks learn response times and produce accurate forecasts using only precipitation and temperature
  • Incorporating multiple timescales of “hydrologic-memory” for both dominant and subordinate processes is essential for accurate forecast

Open Access

Hydrology of a Perennial Firn Aquifer in Southeast Greenland: An Overview Driven by Field Data

  • First Published: 04 May 2020
Key Points

  • Seasonal recharge supplies thermal energy and water to maintain a firn aquifer
  • Firn temperature controls aquifer geometry
  • The recently formed aquifer has a mean residence time of about 6.5 ± 4 years and has expanded upslope since 2010

Free Access

Impacts of Suspended Clay Particle Deposition on Sand-Bed Morphodynamics

  • First Published: 12 May 2020
Key Points

  • Initially suspended fine clay particles within the water column rapidly accumulate within the sediment bed due to hyporheic exchange
  • Fine clay particle storage occurs beneath the mobile layer of the sediment bed defined by the extent of bedform scour
  • Formation of the fine particle layer results in reductions of bedform celerity, height, and sediment flux while length is unchanged

Free Access

An Analytical Framework for Reservoir Operation With Combined Natural Inflow and Controlled Inflow

  • First Published: 17 May 2020
Key Points

  • Hedging rules for reservoir operation with combined natural inflow and controlled inflow are derived
  • We analyze the effect of forecast uncertainty and water transfer capacity on water transfer and reservoir release decisions
  • We identify the uncertainty threshold of natural inflow that controls the decisions

Free Access

Curbing the Summer Surge: Permanent Outdoor Water Use Restrictions in Humid and Semiarid Cities

  • First Published: 20 May 2020
Key Points

  • Water production records from 15 Canadian cities show a decline in per-capita demand, with rate of decline greater in semiarid cities with high seasonal variability
  • Permanent water use restrictions have only minor impacts on mean or median summer day water demands
  • However, stringent restrictions are shown to reduce demand variability at the daily scale, reduce peaks, and suppress demand surges during heat events

Free Access

Hydrological Model Calibration for Dammed Basins Using Satellite Altimetry Information

  • First Published: 22 May 2020
Key Points

  • A novel satellite-based modeling approach for hydrological model calibration of dammed basins is proposed
  • Hydrological modeling of the case basins is effectively improved after introducing the satellite altimetry reservoir level data
  • Reservoir inflow of the case basins is effectively retrieved by the model calibrated using satellite altimetry data

Free Access

Spatial Variability in Bankfull Stage and Bank Elevations of Lowland Meandering Rivers: Relation to Rating Curves and Channel Planform Characteristics

  • First Published: 25 May 2020
Key Points

  • A lidar-based methodology reveals inherent variability in bankfull stage and bank elevations for three meandering river channels
  • Mean variation in bankfull stage is 10% to 20% of the average channel depth
  • The elevation range of mean variation in bankfull stage corresponds to the zone of high curvature in rating curves

Free Access

Lagrangian Modeling of Mixing-Limited Reactive Transport in Porous Media: Multirate Interaction by Exchange With the Mean

  • First Published: 02 June 2020
Key Points

  • We develop a new approach to reactive transport modeling that accounts for the dynamics of small-scale concentration fluctuations
  • The temporal evolution of integratedmixing metrics agrees with the characteristic trends of fully resolved systems
  • Experimental observations of mixing-limited reactive transport are successfully reproduced

Free Access

Modeling the Role of Root Exudation in Critical Zone Nutrient Dynamics

  • First Published: 11 June 2020
Key Points

  • Roots influence subsurface biogeochemical dynamics and mediate microbial dynamics and associated geochemical feedbacks via exudation
  • Root exudates both enhance microbial activity, such as through glucose production, and inhibit it, such as through production of flavonoids
  • Here, the highest sensitivity of exudation's effect on nutrient dynamics results from nitrification inhibition through flavonoid exudation

Free Access

A Calibration Framework for High-Resolution Hydrological Models Using a Multiresolution and Heterogeneous Strategy

  • First Published: 12 June 2020
Key Points

  • A novel framework is developed for automatic calibration of computationally demanding hydrological models with a large number of parameters
  • The framework alleviates equifinality, and calibrated parameters achieve more reasonable values that better correspond to physical reality
  • The framework leads to faster improvement and smoother convergence to optimal objective values and is tested with 134 calibration parameters

Free Access

Trade-Offs Between 1-D and 2-D Regional River Hydrodynamic Models

  • First Published: 14 June 2020
Key Points

  • We develop a 2-D regional-scale coupled hydrologic-hydrodynamic model in the light of multisatellite visibility
  • 2-D model better represents complex wetlands but provides similar results to 1-D on discharge and water levels for large river networks
  • Dimensionality is more important than coupling hydrological-hydrodynamic processes to represent the hydraulics of complex tropical wetlands

Free Access

Assessing Temporal Changes in Groundwater Recharge Using Spatial Variations in Groundwater Ages

  • First Published: 19 June 2020
Key Points

  • We demonstrate that spatial variations in groundwater ages can be used to infer temporal changes in recharge
  • We used measurements of 14C and CFC-12 to quantify changes in ephemeral recharge from a stream in northwest Australia
  • We found that infiltration of mine discharge water increased recharge by up to 75% of natural recharge values

Free Access

Emergent Hydrodynamics and Skimming Flow Over Mussel Covered Beds in Rivers

  • First Published: 19 June 2020
Key Points

  • Partially exposed mussels disrupt the distribution and magnitudes of longitudinal flow velocity and Reynolds shear stress depending on mussel density
  • Above densities of 25 mussels m−2, a hydrodynamic transition occurs that reduces longitudinal flow velocity and turbulent shear stress near the bed
  • Mussel-induced skimming flow decreases the dislodgment potential and thereby enhances bed stability and the long-term persistence of mussels

Free Access

The Utility of Optical Satellite Winter Snow Depths for Initializing a Glacio-Hydrological Model of a High-Elevation, Andean Catchment

  • First Published: 20 June 2020
Key Points

  • Pléiades snow depths aid simulation of snow cover extent, glacier mass balance, and monthly streamflow
  • Alternative snow depth initial conditions underestimate early spring streamflow by up to 48%
  • Sensitivity to temperature means estimating total snow volume with elevation is most important to model snowmelt and streamflow

Open Access

Effects of Successive Peak Flow Events on Hyporheic Exchange and Residence Times

  • First Published: 21 June 2020
Key Points

  • Dynamic response of hyporheic exchange fluxes, residence times, and breakthrough curves to successive peak flow events is investigated
  • Increased time lag between successive flow peaks cause higher temporal variability in mean residence times of hyporheic water
  • Two events can be treated separately if the occurrence of subsequent event is longer than the memory of the system from the antecedent event

Free Access

Response of In-Stream Wood to Riparian Timber Harvesting: Field Observations and Long-Term Projections

  • First Published: 22 June 2020
Key Points

  • In-stream wood data spanning 45 years reflect historical timber harvesting, with widespread loss of wood in logjams
  • Using a wood budget model, time to minimum storage and to storage recovery are projected as 50 and 200 years, respectively
  • Model results indicate that harvesting severity impacts the magnitude of wood loss, but less so the recovery time

Free Access

Runoff and Evapotranspiration Elasticities in the Western United States: Are They Consistent With Dooge's Complementary Relationship?

  • First Published: 22 June 2020
Key Points

  • Elasticities of runoff to precipitation are more consistent across basins than are runoff elasticities to potential evapotranspiration
  • Complementarity in precipitation and potential evapotranspiration elasticities is better met in model- than observation-based estimates
  • Observation-based PET elasticity estimates are more sensible when a complementary relationship constraint is imposed

Free Access

Can Managed Aquifer Recharge Mitigate the Groundwater Overdraft in California's Central Valley?

  • First Published: 22 June 2020
Key Points

  • The impact of Managed Aquifer Recharge (MAR) on Central Valley's (CV) groundwater storage varies strongly from north to south
  • Absent movement of water from north to south, MAR can recover relatively little of the existing groundwater overdraft in the southern CV
  • Delivery of excess winter flows from the northern CV to the south would allow much of the existing groundwater overdraft to be mitigated

Open Access

Unravelling Effects of the Pore-Size Correlation Length on the Two-Phase Flow and Solute Transport Properties: GPU-based Pore-Network Modeling

  • First Published: 23 June 2020
Key Points

  • A novel fully GPU-based pore-network model simulates two-phase flow and transport at the centimeter-scale
  • A semianalytical equation for mass transfer across flowing and stagnant regions is validated against simulation results
  • Pore-size correlation length controls the constitutive relations for two-phase flow and transport through porous media

Free Access

Generalized Sub-Gaussian Processes: Theory and Application to Hydrogeological and Geochemical Data

  • First Published: 25 June 2020
Key Points

  • We develop the theoretical formulation of the Generalized Sub-Gaussian (GSG) model for a general distributional form of the subordinator
  • The GSG formulations tested on laboratory- and field-scale data effectively capture the observed scale dependence of increments' statistics
  • Our formulations can improve flexibility and accuracy of the GSG model, supporting its applicability to a wide range of data

Free Access

Water Demand Forecasting Accuracy and Influencing Factors at Different Spatial Scales Using a Gradient Boosting Machine

  • First Published: 29 June 2020
Key Points

  • The Mean Absolute Percentage Error increases exponentially from 3.2% to 17% for a reduction in group size from 600 to 5 households
  • Past consumption data and household characteristics are important predictors of consumption for smaller aggregations of properties
  • The weather influence on consumption only becomes visible for larger aggregations of properties

Open Access

Seasonal Turbidity Linked to Physical Dynamics in a Deep Lake Following the Catastrophic 2014 Mount Polley Mine Tailings Spill

  • First Published: 29 June 2020
Key Points

  • Quesnel Lake turned bright green when turbid spill material trapped in the hypolimnion mixed to the surface during autumn 2014 turnover
  • Seasonal turbidity increases since the spill are likely due to resuspension of spill-related bottom sediment by internal seiches
  • Physical dynamics are key to understanding the long-term impact of acute and chronic mine spills even in deep aquatic systems

Free Access

Trends in Global Flood and Streamflow Timing Based on Local Water Year

  • First Published: 29 June 2020
Key Points

  • The water year definition can change the direction of trends in streamflow timing
  • By using a local water year, flood timing can often be approximated by a normal distribution
  • Shifts in flood timing are systematically greater than those in the center timing of streamflow

Open Access

Spatial and Temporal Evaluation of Radar Rainfall Nowcasting Techniques on 1,533 Events

  • First Published: 29 June 2020
Key Points

  • A large-sample analysis of 1,533 events is used to determine the skill of radar rainfall nowcasts
  • Evaluation takes place with four nowcasting algorithms from the Pysteps and Rainymotion libraries
  • Nowcast skill is found to depend on event duration, season, catchment size, and location

Free Access

Using Unsupervised Machine Learning to Characterize Capillary Flow and Residual Trapping

  • First Published: 29 June 2020
Key Points

  • An automated unsupervised machine learning method is developed to differentiate flow regimes and identify capillary heterogeneity trapping
  • Capillary- and viscous-dominated flow regimes can be differentiated by combining time series clustering and hypothesis testing
  • This work shows the promise of machine learning methods for analyzing large data sets from coreflooding experiments

Free Access

Implications of Peat Soil Conceptualization for Groundwater Exfiltration in Numerical Modeling: A Study on a Hypothetical Peatland Hillslope

  • First Published: 02 July 2020
Key Points

  • Peat soil layer geometry controls spatial pattern and extent of simulated groundwater exfiltration flux
  • Landscape slope and porous media hydraulic properties control total groundwater exchange flux magnitude more than peat layer geometry
  • Hydrological impact of groundwater drawdown near groundwater-fed peatlands is not captured by monitoring peatland groundwater levels alone

Free Access

Synergistic Impacts of Rainfall Variability and Land Use Heterogeneity on Nitrate Retention in River Networks: Exacerbation or Compensation?

  • First Published: 04 July 2020
Key Points

  • The increase in rainfall variability could lead to significant reduction in the overall nitrate removal by increasing streamflow variability
  • Spatial heterogeneity in lateral input could have impact on overall nitrate removal when they are scaled with distance to outlet
  • Better land use management is capable to compensate the increasing risk of eutrophication caused by climate change induced rainfall change

Free Access

Freezing Level Forecast Error Can Consume Reservoir Flood Control Storage: Potentials for Lake Oroville and New Bullards Bar Reservoirs in California

  • First Published: 04 July 2020
Key Points

  • The narrow elevation bands make the hydrology of Feather and Yuba River Watersheds especially susceptible to freezing level forecast error
  • A freezing level forecast error of 350 m is equivalent to a runoff volume uncertainty up to over a half of the reservoir flood pool storage
  • With the same forecast error, every inch of precipitation can amount to more than 3% of the reservoir flood pool storage

Free Access

LIDA: A Land Integrated Data Assimilation Framework for Mapping Land Surface Heat and Evaporative Fluxes by Assimilating Space-Borne Soil Moisture and Land Surface Temperature

  • First Published: 04 July 2020
Key Points

  • A Land Integrated Data Assimilation framework (LIDA) based on the variational data assimilation technique is proposed
  • LIDA maps surface heat and evaporative fluxes over the U.S. Southern Great Plains by assimilating GOES LST and SMAP SM
  • LIDA estimates the uncertainty of estimated parameters, hence fluxes, by calculating the error covariance matrix of parameters

Open Access

Dual-Permeability Model Improvements for Representation of Preferential Flow in Fractured Clays

  • First Published: 06 July 2020
Key Points

  • Dual-permeability model improvement for modeling wide fractures by reformulating the α parameter in the Mualem-van Genuchten model soil water retention curve (SWRC)
  • Rigorous evaluation of the dual-permeability interface mass exchange function
  • SWRC exponent n sensitivity analysis for dual-permeability model

Free Access

Calibrated Simulation of the Long-Term Average Surficial Groundwater System and Derived Spatial Distributions of its Characteristics for the Contiguous United States

  • First Published: 08 July 2020
Key Points

  • Calibrated simulations of the shallow groundwater system were used to estimate the CONUS-extent spatial distribution of transmissivity
  • Correlations were explored between the estimated transmissivities and recharge, elevation, and topographic slope
  • Simulated depth to water and groundwater discharge were used to derive unsaturated zone properties and long-term average base-flow on the NHDPlusV2 stream network

Free Access

The Role of Fire in the Coevolution of Soils and Temperate Forests

  • First Published: 11 July 2020
Key Points

  • Wildfire strongly influences forest hydrogeomorphology, yet its net effect on coevolution of soil-vegetation systems is not yet constrained
  • We used a new numerical model to test the hypothesis that fire is central to coevolution of forest-soil systems in SE Australia
  • The hypothesis was supported, and the role of fire was found to increase with aridity due to higher fire frequency and less developed soils

Open Access

Improving Forecast Skill of Lowland Hydrological Models Using Ensemble Kalman Filter and Unscented Kalman Filter

  • First Published: 13 July 2020
Key Points

  • The ensemble Kalman filter and unscented Kalman filter are utilized to improve forecast skill of a hydrological model by state estimation
  • Both approaches have improved the forecast performance, with unscented Kalman filter being the computationally leaner option
  • The unscented Kalman filter can be considered as a new and effective option to assimilate observations into low-dimensional models

Free Access

One Flood Is Not Enough: Pool-Riffle Self-Maintenance Under Time-Varying Flows and Nonequilibrium Multifractional Sediment Transport

  • First Published: 13 July 2020
Key Points

  • We conducted novel experiments to evaluate pool-riffle self-maintenance considering a sequence of floods with realistic sediment supply
  • We identified the effects of initial sediment sorting, nonequilibrium sediment transport, and hydrograph duration on self-maintenance
  • Full self-maintenance may not be achieved in individual floods because self-maintenance mechanisms compete with upstream sediment supply

Free Access

A Semianalytical Interface Model of Soil Freeze/Thaw and Permafrost Evolution

  • First Published: 13 July 2020
Key Points

  • A novel semianalytical model of soil freeze and thaw is presented for application in hydrology
  • The model is numerically stable and scale insensitive
  • The model is up to 3 orders of magnitude faster than continuum equivalent

Free Access

Quantitative Flow-Ecology Relationships Using Distributed Lag Nonlinear Models: Large Floods in the Murray River Could Have Delayed Effects on Aquatic Macroinvertebrates Lasting More Than Three Decades

  • First Published: 13 July 2020
Key Points

  • Long-term data on macroinvertebrates, water quality, and hydrology in the Murray River enabled quantifying the flow-ecology relationship
  • Flood impacts on macroinvertebrate abundance and richness may persist for decades, while small to medium flows have indiscernible effects
  • A flood-induced influx of organic matter might underlie the apparent long-term effect of floods

Free Access

Generating Proxy SWOT Water Surface Elevations Using WRF-Hydro and the CNES SWOT Hydrology Simulator

  • First Published: 16 July 2020
Key Points

  • Two approaches for generating proxy SWOT water surface elevations from a hydrology modeling framework are provided
  • Proxy SWOT data are well-suited for societal applications and scientific studies prior to and following launch
  • The Large-Scale SWOT Hydrology Simulator provides realistic proxy SWOT data for error budget studies

Free Access

What Is a Debris Flood?

  • First Published: 16 July 2020
Key Points

  • Debris floods are poorly defined. We provide a definition based on exceedance of a critical shear stress associated with large grains
  • We classify three types of debris floods based on their triggering mechanisms
  • We further subcategorize debris floods by magnitude into onset, damaging, and catastrophic

Free Access

Inflow Dynamics in Weakly Stratified Lakes Subject to Large Isopycnal Displacements

  • First Published: 16 July 2020
Key Points

  • Large-amplitude isopycnal displacements can strongly affect river intrusion depths in weakly stratified lakes
  • Strong downwelling near the inlet promotes metalimnetic river intrusions while strong upwelling, bottom intrusions in the near field
  • Basin scale internal circulation can either accelerate or decelerate lateral transport across lake depending on wind direction

Free Access

Improved Characterization of DNAPL Source Zones via Sequential Hydrogeophysical Inversion of Hydraulic-Head, Self-Potential and Partitioning Tracer Data

  • First Published: 16 July 2020
Key Points

  • The low-cost self-potential (SP) method improves the results of effective hydraulic conductivity (Keff) estimation
  • Using a sequential strategy, the improved Keff estimation from SP can increase the accuracy of DNAPL mapping
  • The sequential inversion framework helps in reducing significantly the computational effort for DNAPL inversion

Open Access

The Stream Length Duration Curve: A Tool for Characterizing the Time Variability of the Flowing Stream Length

  • First Published: 17 July 2020
Key Points

  • The concept of Stream Length Duration Curve is formalized and applied to a real-world case study
  • Stochastic models are developed to link the Stream Length Duration Curve to the network structure and local hydrological properties
  • In the Valfredda catchment (Italy), the activation of temporary reaches follows a hierarchical order

Free Access

Experimental Investigation on the Movability of Water in Shale Nanopores: A Case Study of Carboniferous Shale From the Qaidam Basin, China

  • First Published: 17 July 2020
Key Points

  • The TPG was investigated and discussed, combining the step-by-step depressurization experimental method and DLVO theory
  • The distribution and proportion of water with four different movability are analyzed based on the solid-liquid interfacial forces
  • The increase of moving ratio of water in shale nanopores with the pressure gradient leads to an increase in water permeability

Free Access

Coupled Time-Lapse Full-Waveform Inversion for Subsurface Flow Problems Using Intrusive Automatic Differentiation

  • First Published: 06 July 2020
Key Points

  • We assimilated seismic waveform data to directly invert for hydrological subsurface properties (e.g., permeability)
  • Coupled inversion leads to more accurate inversion results compared to decoupled inversion
  • We adopted an intrusive automatic differentiation strategy with custom operators for high computational efficiency and scalability

Free Access

Recent Trends in Individual and Multivariate Compound Flood Drivers in Canada's Coasts

  • First Published: 19 July 2020
Key Points

  • Multivariate trend analysis of hydroclimatic and coastal variables shows increasing risks of compound flooding in several areas
  • Precipitation and skew surge show both positive correlations and increasing joint trends along the Atlantic and parts of the Pacific coasts
  • A multivariate trend analysis index is proposed to investigate compound flooding regionally and at individual locations

Free Access

Temporal Networks-Based Approach for Nonstationary Hydroclimatic Modeling and its Demonstration With Streamflow Prediction

  • First Published: 19 July 2020
Key Points

  • Concept of temporal networks is proposed for temporally evolving hydroclimatic systems that are characterized by inherent nonstationarity
  • Proposed approach is applied to hydroclimatic modeling of streamflow that is associated with a large pool of influencing variables
  • Temporal variability in hydroclimatic association of streamflow is relatively high in monsoon season, and less in summer and winter seasons

Open Access

Toward Global Stochastic River Flood Modeling

  • First Published: 19 July 2020
Key Points

  • Large-scale flood hazard models typically neglect to represent the spatial dependence of real flood events
  • Relative flow exceedances simulated by the fusion of global hydrological with statistical models reproduce gauge-driven flood event sets
  • At the continental scale, key characteristics of a flood risk model are indistinguishable when driven with observed versus modeled flow data

Free Access

Permeability Impairment and Salt Precipitation Patterns During CO2 Injection Into Single Natural Brine-Filled Fractures

  • First Published: 22 July 2020
Key Points

  • We numerically model formation dry-out due to supercritical CO2 injection into a single natural fracture
  • Volume of precipitated salt is not a direct indicator for the absolute permeability reduction of a single fracture
  • Salt precipitation patterns in the fracture space vary significantly with the applied effective normal stress

Free Access

Poroelastic Solution for the Nonlinear Injectivity of Subsurface Rocks With Strain-Induced Permeability Variations

  • First Published: 23 July 2020
Key Points

  • An analytical solution to the well injectivity index considering stress-sensitive permeability is proposed
  • Permeability variation is formulated as a nonlocal function of the pore fluid pressure
  • The influence of rock poroelastic parameters on well injectivity is discussed

Open Access

Using Complex Network Analysis for Optimization of Water Distribution Networks

  • First Published: 23 July 2020
Key Points

  • Patterns of optimal water networks are identified with complex network analysis
  • A network theory-based design approach is developed, which partly outperforms a multiobjective evolutionary design approach
  • The new approach achieves runtime reductions up to 5 orders of magnitude and is capable of designing large networks (>150,000 pipes)

Free Access

Splitting Dynamics of Liquid Slugs at a T-Junction

  • First Published: 27 July 2020
Key Points

  • A quasi-static model for dynamic splitting of liquid slugs at a T-junction is proposed and validated against experiments
  • A critical initial slug length is identified that separate two splitting regimes
  • Dynamic contact angles strongly impact meniscus velocities and splitting dynamics

Open Access

A Systematic Approach to Hydrogeological Conceptual Model Testing, Combining Remote Sensing and Geophysical Data

  • First Published: 27 July 2020
Key Points

  • Increasing confidence in conceptual models through an exploratory systematic testing framework based on Popper-Bayes philosophy
  • A general framework for transparent and reproducible development and testing of hydrogeological conceptual models is applied
  • Refraction seismic data and satellite imagery tests the conceptualization of sinkhole-like depressions as conduits of recharge

Free Access

Regime Identification, Dimensionless Numbers, and Parameter Sensitivity of Variable-Density Flow in Porous Media Based on Numerical Simulations

  • First Published: 27 July 2020
Key Points

  • Three end-member flow regimes are identified based on numerical simulations of variable-density flow in porous media with various settings
  • Three dimensionless numbers can distinguish the flow regimes observed in our simulations and published experimental results
  • The flow regimes and regime shifts are mainly controlled by dimensionless-number-related parameters

Free Access

A Geochemical Record of Late-Holocene Hurricane Events From the Florida Everglades

  • First Published: 27 July 2020
Key Points

  • This study demonstrates the use of XRF analysis in detecting major hurricane events in sand-limited coastal systems
  • Five active hurricane periods were identified at ~3,400–3,000, ~2,200–1,500, ~1,000–800, ~600–300, and ~150 cal yr BP to present
  • This study suggests that intense hurricane activities in the western Atlantic Basin were modulated by ITCZ, ENSO, and NAO activities

Free Access

Preconditioned Crank-Nicolson Markov Chain Monte Carlo Coupled With Parallel Tempering: An Efficient Method for Bayesian Inversion of Multi-Gaussian Log-Hydraulic Conductivity Fields

  • First Published: 03 August 2020
Key Points

  • We proposed an efficient MCMC method called pCN-PT for Bayesian inversion of multi-Gaussian log-hydraulic conductivity fields
  • We demonstrated that pCN-PT can estimate and conditionally sample multi-Gaussian random fields in high-dimensional linear and nonlinear problems
  • Parallel tempering can improve the performance of pCN-MCMC

Free Access

Stochastic Hydro-Financial Watershed Modeling for Environmental Impact Bonds

  • First Published: 03 August 2020
Key Points

  • A stochastic watershed modeling framework is developed to support the development of an environmental impact bond
  • Bond period and interest rates are linked to distributions of costs that account for aleatory and epistemic uncertainty
  • The feasibility of financing interventions to address watershed erosion problems at the U.S.-Mexico border is shown

Free Access

Depth of Solute Generation Is a Dominant Control on Concentration-Discharge Relations

  • First Published: 03 August 2020
Key Points

  • Vertical distribution of solute is a stronger control of concentration-discharge relation than temporal dynamics of precipitation inputs
  • Solutes of anthropogenic origin show much larger variability than geogenic solutes
  • Numerical experiments help the interpretation of variability in C-Q relations among solutes

Free Access

Nitrate Removal Across Ecogeomorphic Zones in Wax Lake Delta, Louisiana (USA)

  • First Published: 03 August 2020
Key Points

  • NDVI, a vegetation index, is a useful predictor of nitrate removal in delta environments
  • Intermediate elevation areas are hot spots for nitrate removal on Wax Lake Delta
  • Eastern channels receive and remove more nitrate from Wax Lake Delta

Free Access

The Counteracting Effects of Snowmelt Rate and Timing on Runoff

  • First Published: 03 August 2020
Key Points

  • Potential runoff was most sensitive to snowmelt rate in California, USA, and snowmelt timing in Colorado, USA
  • Energy availability and plant available water storage controlled intersite differences
  • Decreased runoff due to slower snowmelt was counterbalanced by increases due to earlier snowmelt timing

Free Access

Integration of Submerged Aquatic Vegetation Motion Within Hydrodynamic Models

  • First Published: 03 August 2020
Key Points

  • A model is presented to capture the changing position of Submerged Aquatic Vegetation blades and validated using laboratory experiments
  • Forcing terms that control seagrass movement within a meadow are evaluated
  • Estimates of deflected vegetation height and bulk meadow friction coefficients demonstrate the importance of simulating SAV motion

Free Access

Drag Coefficient of Emergent Flexible Vegetation in Steady Nonuniform Flow

  • First Published: 04 August 2020
Key Points

  • The drag of an emergent flexible vegetation array under steady nonuniform flow is explored using the Saint-Venant equation
  • A formula for the flexible drag coefficient is proposed which exhibits nonmonotonic variation along the vegetated patch
  • The drag reconfiguration in an emergent flexible vegetation array along the streamwise direction is explored

Open Access

Inference of Transmissivity in Crystalline Rock Using Flow Logs Under Steady-State Pumping: Impact of Multiscale Heterogeneity

  • First Published: 04 August 2020
Key Points

  • Three scales of hydraulic heterogeneity affect variability of measured flowrate and inferred transmissivity
  • Fracture roughness has relatively small impact on inferred transmissivity compared to the fracture-to-fracture scale heterogeneity
  • The median value of inferred transmissivity from flow logs is representative of the underlying transmissivity distribution

Free Access

A Pore-Scale Upscaling Approach for Laminated Sandstones using Minkowski Maps and Hydraulic Attributes

  • First Published: 10 August 2020
Key Points

  • Regional morphological features are introduced and corresponding fields derived efficiently with FFT techniques on tomographic images
  • An upscaling workflow based on 3-D rock types derived from morphological fields was successfully applied to a thin-bedded sandstone
  • Upscaling of transport properties based on the introduced homogenization scheme leads to excellent agreement with direct calculations

Open Access

How to Tailor My Process-Based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures

  • First Published: 10 August 2020
Key Points

  • A flexible simulation environment coupled with dynamic identifiability analysis forms a diagnostic tool for process-based model building
  • Alternative model configurations in terms of process representation, numerical solver, and parametrization are compiled
  • Identifiability of model structures varies in space and time driven by the governing hydro-meteorological conditions

Free Access

Dissolved Organic Carbon and Nitrate Concentration-Discharge Behavior Across Scales: Land Use, Excursions, and Misclassification

  • First Published: 10 August 2020
Key Points

  • Moving window analyses reveal highly variable concentration-discharge relationships for nitrate and fluorescent dissolved organic matter on an intra-annual scale
  • Annual assessments of concentration-discharge relationships mischaracterize the behavior of nitrate and fluorescent dissolved organic matter across watersheds
  • Short-term events lasting a small proportion of the year can determine annual concentration-discharge characterization, emphasizing the importance of high-frequency sampling regimes for understanding solute transport

Free Access

Wind as a Main Driver of Spatial Variability of Surface Energy Balance Over a Shallow 102-km2 Scale Lake: Lake Kasumigaura, Japan

  • First Published: 10 August 2020
Key Points

  • Spatial interpolation of meteorological variables allowed the production of seasonal, annual, and 5-year average lake energy balance maps
  • Latent heat flux and total energy flux into water body exhibited pronounced spatial variability while radiative fluxes were more uniform
  • The dominant northerly wind produced larger turbulent fluxes in the downwind area and hence spatial variability

Free Access

Nonstationary Frequency Analysis of Censored Data: A Case Study of the Floods in the Yangtze River From 1470 to 2017

  • First Published: 11 August 2020
Key Points

  • The nonstationarity and insufficient length of data impact the accuracy of design flood estimation
  • The stationary and nonstationary models considering data type are developed by a covariate method and the likelihood principle
  • Temporal information expansion by censored data corrects the underestimation of probability for rare flood events in the original models

Free Access

Using Remote Sensing Data-Based Hydrological Model Calibrations for Predicting Runoff in Ungauged or Poorly Gauged Catchments

  • First Published: 12 August 2020
Key Points

  • Using bias-corrected remote sensing data to calibrate hydrological model shows great potential especially in ungauged catchments
  • Compared to raw PML-AET, bias-corrected PML-AET improves runoff prediction noticeably and adding GRACE shows limited benefit
  • Gridded application performs better than lumped catchment modeling application for maximizing the benefit from the spatial PML-AET data

Free Access

Rough Correlations: Meta-Analysis of Roughness Measures in Gravel Bed Rivers

  • First Published: 17 July 2020
Key Points

  • The standard deviation of bed elevation σz more universally characterizes bed roughness k than D84 across a wide range of river conditions
  • The Smart and Jäggi equation with σz as k outperforms others based on a large data set of 2,501 measurements under a wide range of conditions
  • Accurate σz measurements require spatial resolution above 2D84 (plane-bed), 0.5 dune wavelength (dune-bed), and inter-step spacing (step-pool)

Free Access

Excess Air Correction of SF6 and Other Dissolved Gases in Groundwater Impacted by Compressed Air From Drilling or Well Development

  • First Published: 14 August 2020
Key Points

  • Compressed air can be a source of excess dissolved gases in groundwater
  • Excess air from drilling might explain elevated SF6 in samples from wells
  • Corrections are sometimes possible using SF6-CFC plots

Open Access

Efficiency and Accuracy of Micro-Macro Models for Mineral Dissolution

  • First Published: 15 August 2020
Key Points

  • We investigate reactive flow and transport problems for mineral dissolution
  • A fully coupled nonlinear micro-macro model is considered including evolving microstructures by means of level-set methods
  • Taking advantage of parallel computing and a tailored adaptivity scheme, computation times are comparable to purely macroscopic simulations

Technical Reports: Data

Free Access

NAC2H: The North American Climate Change and Hydroclimatology Data Set

  • First Published: 29 June 2020
Key Points

  • A data set containing hydrometeorological observations and hydroclimatological simulations for 3,540 watersheds in North America is presented
  • The data set is the first to provide large-sample hydrological simulations and indices in the context of climate change impacts on hydrology
  • This data set can be used for multiple purposes including impact assessment, uncertainty, and hydrological process analysis over large scales

Technical Reports: Methods

Free Access

An Improved Covariate for Projecting Future Rainfall Extremes?

  • First Published: 04 July 2020
Key Points

  • Extreme rainfall does not scale consistently with surface air temperature
  • Integrated water vapor is the most stable covariate when correlated to rainfall
  • It is suggested integrated water be used as a covariate for rainfall projection

Free Access

New Simplified Models of Single-Well Push-Pull Tests With Mixing Effect

  • First Published: 04 July 2020
Key Points

  • New approximate solutions of the SWPP test with wellbore mixing effect are presented
  • The new solution is accurate when Cext(t = 0) = C0
  • New simplified model to estimate retardation factor is presented considering mixing effect

Free Access

Technical Report—Methods: A Diagnostic Approach to Analyze the Direction of Change in Model Outputs Based on Global Variations in the Model Inputs

  • First Published: 06 July 2020
Key Points

  • We bring attention to a diagnostic strategy—assessing the direction of change, which quantifies whether the increase (or decrease) of a model input leads to a positive (or negative) change in a model output variable
  • We developed a quantification and visualization approach to analyze the direction of change due to input variability within a Global Sensitivity Analysis context
  • We demonstrated our approach as a time-varying analysis to diagnose how the parameters of a widely used hydrological model control the output's direction of change

Free Access

Bootstrap Aggregation and Cross-Validation Methods to Reduce Overfitting in Reservoir Control Policy Search

  • First Published: 08 July 2020
Key Points

  • We apply machine learning techniques of bootstrap aggregation (bagging) and cross-validation to improve reservoir control policy search
  • Block bootstrapping of historic hydrology based on paleo-inflows can efficiently generate calibration-validation-testing data
  • Policy selection according to validation performance on bootstrapped data leads to the greatest improvement in out-of-sample performance

Free Access

The Fabrication of Plagioclase Feldspar Microdevices: An Experimental Tool for Pore-Scale Mineral Dissolution Studies

  • First Published: 03 August 2020
Key Points

  • A novel fabrication method is developed to utilize a silicate mineral as a reactive microfluidic substrate
  • Femtosecond laser rapidly ablates microchannels and HF etching removes laser-induced amorphous layer
  • Anorthite dissolution rates measured at far-from-equilibrium conditions correspond to previously reported values