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The Impact of Ice Sheet Geometry on Meltwater Ingress and Reactive Solute Transport in Sedimentary Basins

  •  29 September 2022

Key Points

  • Ice sheet geometry significantly affects groundwater flow patterns and meltwater ingress in sedimentary basins

  • Two-dimensional simulations tend to underestimate meltwater ingress in sedimentary basins

  • Three-dimensional simulations capture lateral flow in aquifers beneath ice sheets and provide more representative results

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Comment on “On the Estimation of Potential Evaporation Under Wet and Dry Conditions” by Z. Tu and Y. Yang

  •  29 September 2022

Key Points

  • The wet-surface temperature estimates of Szilagyi and Jozsa (2008) are more realistic than the ones by Yang and Roderick (2019)

  • The latter estimates are often lower than the corresponding wet-bulb temperatures, which is thermodynamically problematic

  • The same does not happen with the former estimates

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Reply to Comment on “On the Estimation of Potential Evaporation Under Wet and Dry Conditions” by Jozsef Szilagyi

  •  29 September 2022

Key Points

  • The recovered surface temperature using the maximum evaporation approach is physically attainable

  • Allowing net radiation vary with surface wetting/drying is more universally valid

  • The maximum evaporation approach best follows the definition of potential evaporation by Wilfried Brutsaert (2015)

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Issue Information

  •  28 September 2022
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Coupling Machine Learning Into Hydrodynamic Models to Improve River Modeling With Complex Boundary Conditions

  •  28 September 2022

Key Points

  • Coupling machine learning into physical hydrodynamics for river modeling with complex boundary conditions

  • Streamflow and water levels were modeled with Kling-Gupta efficiency coefficient above 0.90 at most hydrologic stations and 38 times faster than traditional 1-D/2-D coupled models

  • The proposed machine learning-based downstream boundary condition showed better performance than the rating curve method

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Backed-Up, Saturated, and Stagnant: Effect of Milldams on Upstream Riparian Groundwater Hydrologic and Mixing Regimes

  •  28 September 2022

Key Points

  • Milldams raise riparian groundwater levels, decrease hydraulic gradients, and cause reversals in groundwater flow

  • Milldam legacies contribute to reduced groundwater mixing in near-stream sediments

  • Altered groundwater regimes due to milldams could affect riparian water quality processes

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Effect of Lateral Outflow on Three-Dimensional Flow Structure in a River Delta

  •  26 September 2022

Key Points

  • Channelized outflow was observed to induce coherent secondary circulations while unchannelized lateral outflow did not

  • Formation of the coherent secondary circulations may depend upon available lateral momentum flux and length scale of outflow in the channel

  • Suspended sediment transport to wetlands may depend on strength of secondary circulation cells

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Hydrograph Shape Impact on Sand Infiltration and Sediment Transport Dynamics in Gravel-Bed Rivers

  •  26 September 2022

Key Points

  • Sand addition enhances sediment dynamics (i.e., entrainment and transport rate)

  • The shape of the rising limb of the hydrograph alters sediment transport and sand infiltration

  • Increased bed porosity and reduced sand infiltration were observed for the rising limb of long time-to-peak flood hydrographs

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Upscaling Hillslope-Scale Subsurface Flow to Inform Catchment-Scale Recession Behavior

  •  26 September 2022

Key Points

  • Hillslope-scale subsurface flow is aggregated in 30 basins to explore topographic controls on catchment-scale recession behavior

  • Upscaling relationships are derived that can predict transient catchment-scale recession behavior in a basin with a homogenous subsurface

  • These relationships successfully approximate numerical solutions, but cannot capture the full extent of observed recession behavior

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Where and When Does Streamflow Regulation Significantly Affect Climate Change Outcomes in the Columbia River Basin?

  •  26 September 2022

Key Points

  • Regulation dampens future winter and summer volume changes where the degree of upstream regulation is large

  • Regulation dampens cool-season high flow extreme increases and amplifies warm-season increases at snow-dominant headwater basins

  • Regulation dampens low flow changes in tributaries with a large degree of upstream regulation but has little to no effect elsewhere

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Microbial Contamination of Groundwater Self-supply in urban Indonesia: Assessment of Sanitary and Socio-economic Risk factors

  •  7 October 2022

Key Points

  • Risk factors for faecal contamination of groundwater self-supply assessed in two Indonesian cities

  • Contamination associated with lower socio-economic status, proximity to sanitation and lack of well protection

  • Widespread boiling of self-supplied water significantly improves microbial quality between source and point-of-use

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Stochastic downscaling of hourly precipitation series from climate change projections

  •  7 October 2022

Key Points

  • This article introduces a non-parametric stochastic process in generating synthetic precipitations for non-stationary climate

  • The basis of this algorithm is highly related to the physcial mechanism of precipitation formation defined by Pressure Change Events (PCEs)

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SWAT_DA: Sequential Multivariate Data Assimilation-Oriented Modification of SWAT

  •  6 October 2022

Key Points

  • We propose a new approach to link SWAT with Data Assimilation (DA) algorithms based on source code modification

  • Snow Cover Fraction (SCF) data of MODIS is assimilated to estimate HRU-scaled snow-related parameters of SWAT

  • Bivariate streamflow and MODIS SCF data assimilation mitigates the equifinality problem

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Seasonal patterns of mixing and arsenic distribution in a shallow urban lake

  •  6 October 2022

Key Points

  • In polymictic, temperate lakes, stratification and high temperatures are needed to promote anoxia and arsenic release in bottom water

  • Convective mixing is a key mechanism transporting arsenic from lake bottom waters to surface waters inhabited by oxygen-requiring biota

  • Arsenic release in shallow, temperate lakes overlaps with high primary producer growth and leads to arsenic accumulation in the food web

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Influence of Shallow Groundwater Evapotranspiration on Recharge Estimation Using the Water Table Fluctuation Method

  •  5 October 2022

Key Points

  • Seasonal variations in ET bias groundwater level recession rates in shallow aquifers

  • Seasonal recharge estimates from Water Table Fluctuation method can be markedly different depending on whether seasonal variations in recession rates are accounted or not

  • Two novel methods to quantify ET’s influence on groundwater recession, and consequently on seasonal recharge, are presented

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Characterizing Groundwater Chemistry and Recharge in the Critical Zone of an Agricultural Claypan Watershed

  •  3 October 2022

Key Points

  • Groundwater chemistry was dominated by chemical equilibrium in perched and shallow aquifers (<4 m) and mixing in the deeper aquifers

  • Groundwater in the deeper aquifers was recharged by groundwater from similar depths and above strata but via heterogeneous pathways

  • Complex recharge and nitrate transport routes pose a challenge for legacy nitrogen mitigation in regions with restrictive soil horizons

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Drought Conditions Enhance Groundwater Table Fluctuations caused by Hydropower Plant Management

  •  3 October 2022

Key Points

  • Wavelet power spectrum and coherence analysis is used to study river-aquifer interactions under dam operations in an Alpine catchment

  • The impact of reservoir operations on the aquifer is strongest under low flow conditions but the area impacted shows little variation

  • Under low flow conditions, dam operations considerably influence the frequency of the water exchange between rivers and aquifer

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Technical Note: Can Gauss-Newton algorithms outperform stochastic optimization algorithms when calibrating a highly parameterized hydrological model? A case study using SWAT

  •  29 September 2022

Key Points

  • Comprehensive comparison of Gauss-Newton and stochastic optimization algorithms on a 38 parameter SWAT calibration problem with fixed budget

  • Gauss-Newton algorithms can perform better than stochastic algorithms, especially when target NSE is high or budget is limited

  • The Robust Gauss-Newton algorithm has fastest initial convergence and is particularly attractive when budget is tight (e.g., 200 model runs)

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Remote Sensing of Groundwater: Current Capabilities and Future Directions

  •  29 September 2022

Key Points

  • Accurately measuring and monitoring groundwater storage and fluxes is critical for water, food, and energy security

  • Remote sensing approaches such as gravitational measurements, InSAR, GNSS, lidar altimetry, and AEM can yield indirect yet valuable information about groundwater

  • Fusing multiple remotely-sensed datasets or employing other tools such as numerical models increase the applicability of individual approaches

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Using Mutual Information for Global Sensitivity Analysis on Watershed Modeling

  •  29 September 2022

Key Points

  • Mutual information uses fewer model runs to provide consistent sensitivity rankings on SWAT parameters as Sobol sensitivity analysis

  • Statistical significance test accelerates convergence of mutual information calculations

  • We identify the dominant sensitivities on subsurface and snow parameters in agriculture and snow-dominated watersheds, respectively

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The Millennium Drought in southeast Australia (2001–2009): Natural and human causes and implications for water resources, ecosystems, economy, and society

Key Points

  • Drivers and impacts of Australia's record drought were analyzed
  • Impacts accumulated and propagated through the water cycle at different rates
  • Future droughts may not be managed better than past ones.

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The WFDEI meteorological forcing data set: WATCH Forcing Data methodology applied to ERA-Interim reanalysis data

Key Points

  • Global three hourly meteorological forcing data at half-degree spatial resolution
  • Covers 1979–2012
  • Improvements compared to the WATCH forcing data

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Macropores and water flow in soils revisited

Key Points

  • Darcy-Richards is inadequate
  • Stokes flow may be useful in some circumstances
  • Still important questions to be resolved in soil physics

Open access

Combined Modeling of US Fluvial, Pluvial, and Coastal Flood Hazard Under Current and Future Climates

Key Points

  • First complete high-resolution flood hazard analysis of conterminous US flood risk from all major sources (fluvial, pluvial, and coastal)

  • In validation tests the model achieved Critical Success Index scores of 0.69–0.82, similar to many local custom-built 2D models

  • By 2050, flood hazard increases for the Eastern seaboard and Western states, but decreases or changes little for the center and South-West

Plain Language Summary

We develop a method to estimate past, present, and future flood risk for all properties in the conterminous United States whether affected by river, coastal or rainfall flooding. The analysis accounts for variability within environmental factors including changes in sea level rise, hurricane intensity and landfall locations, precipitation patterns, and river discharge. We show that even for a conservative climate change trajectory we can expect locally significant changes in the land area at risk from floods by 2050, and by this time defenses protecting 2,200 km2 of land may be compromised. The complete dataset has been made available via a website (https://floodfactor.com/) created by the First Street Foundation in order to increase public awareness of the threat posed by flooding to safety and livelihoods.

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Satellite Remote Sensing for Water Resources Management: Potential for Supporting Sustainable Development in Data-Poor Regions

Key Points

  • Satellite remote sensing is being incorporated into water resources management but is generally underutilized
  • New and proposed missions have the potential to transform water resources management for sustainable development, especially in data-poor regions
  • Ongoing challenges of accuracy, sampling, and continuity and capacity development need to be addressed, as well as new challenges of information volume and diversity

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The science and practice of river restoration

Key Points

  • River restoration is a prominent area of applied water-resources science
  • restoration includes connectivity, physical-biotic interactions, and history
  • effective restoration requires collaboration among scientists and practitioners

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The Millennium Drought in southeast Australia (2001–2009): Natural and human causes and implications for water resources, ecosystems, economy, and society

Key Points

  • Drivers and impacts of Australia's record drought were analyzed
  • Impacts accumulated and propagated through the water cycle at different rates
  • Future droughts may not be managed better than past ones.

Open access

Water Use in Global Livestock Production—Opportunities and Constraints for Increasing Water Productivity

Key Points

  • Annually, 4,387 km3 of water is required to produce the feed consumed by the global livestock sector, of which 94% is green water
  • Opportunities for increasing livestock water productivity exist for all livestock types but are particularly large for ruminants
  • Water productivity improvements for ruminants through supplementation with feed crops are constrained by high water cost to produce crops

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Quantifying renewable groundwater stress with GRACE

Key Points:

  • Renewable groundwater stress is quantified in the world's largest aquifers
  • Characteristic stress regimes are defined to determine the severity of stress
  • Overstressed aquifers are mainly in rangeland biomes with some croplands

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The twenty-first century Colorado River hot drought and implications for the future

Key Points

  • Record Colorado River flow reductions averaged 19.3% per year during 2000–2014. One-third or more of the decline was likely due to warming
  • Unabated greenhouse gas emissions will lead to continued substantial warming, translating to twenty-first century flow reductions of 35% or more
  • More precipitation can reduce the flow loss, but lack of increase to date and large megadrought threat, reinforce risk of large flow loss

Plain Language Summary

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. Approximately one-third of the flow loss is due to high temperatures now common in the basin, a result of human caused climate change. Previous comparable droughts were caused by a lack of precipitation, not high temperatures. As temperatures increase in the 21st century due to continued human emissions of greenhouse gasses, additional temperature-induced flow losses will occur. These losses may exceed 20% at mid-century and 35% at end-century. Additional precipitation may reduce these temperature-induced losses somewhat, but to date no precipitation increases have been noted and climate models do not agree that such increases will occur. These results suggest that future climate change impacts on the Colorado River will be greater than currently assumed. Reductions in greenhouse gas emissions will lead to lower future temperatures and hence less flow loss.

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