Water Resources Research is an open access journal that publishes original research articles and commentaries on hydrology, water resources, and the social sciences of water that provide a broad understanding of the role of water in Earth’s system.

In Memoriam: Harihar Rajaram
July 9, 2024

With deep sadness and an appreciation for his enormous contributions to the Earth and space sciences, AGU shares news of the loss of one of our esteemed, much-loved colleagues, Harihar Rajaram.

An AGU Fellow and longtime affiliate of the Hydrology Section, Dr. Rajaram was the Editor-in-Chief of Geophysical Research Letters (GRL) since 2019, a former editor on Water Resources Research (WRR), and served on the AGU Publications Committee.

Hari had a boundless energy. His thoughtfulness, diligence, dedication, sense of humor, and above all, his absolute kindness, will be missed. Even when dealing with the trickiest of situations on AGU journals, Hari never complained or quit. He found a way through bringing people together and finding solutions.

A professor in the Department of Environmental Health and Engineering at The Johns Hopkins University, Hari’s colleagues, Ed Schlesinger, the Benjamin T. Rome Dean and Department Chair Marsha Willis-Karp, shared the following remembrance.

The family obituary with many poignant remembrances is here with the suggestion of donations, in lieu of flowers, to the local Baltimore charity Beans and Bread.

Hari’s grounded perspective, exemplary scholarship, and warm friendship made a meaningful impact on all who knew him and worked beside him. May his memory leave a lasting impact on the Hydrology community and to his friends and colleagues around the world.



Water Resources Research is now a fully open access journal

AGU remains committed to open science and open data. As part of our mission, we are focused on making science available to the widest possible audience. With the growing open access requirements placed by funders on researchers around the world, this transition to an open access model also makes compliance easier.

All articles in the journal are open access as of 1 January 2024. For more information, including funding options for publishing fees, please visit the FAQ.

Browse Articles

Open access

UAV‐Based Land Surface Temperatures and Vegetation Indices Explain and Predict Spatial Patterns of Soil Water Isotopes in a Tropical Dry Forest

  •  14 February 2025

Graphical Abstract

UAV-Based Land Surface Temperatures and Vegetation Indices Explain and Predict Spatial Patterns of Soil Water Isotopes in a Tropical Dry Forest Issue 2, 2025

Graphical abstract illustrating the concept of isotopic enrichment of soil water depending on canopy status and plant type. Because of less shading provided, evaporative enrichment in areas without canopy cover is higher compared to areas with intermixed evergreen and leaf-shedding trees and evergreen patches. E and T are Evaporation and Transpiration, respectively.

Open access

The Storage and Operation Changes of 256 Reservoirs Across the Contiguous United States

  •  14 February 2025

Key Points

  • Changes in reservoir storage and operation rules and practices are identified for 256 reservoirs in the Contiguous United States

  • The increasing trend of storage is mainly due to operational changes, while the decreasing trend is due to sedimentation and inflow changes

  • Both operation effectiveness and deficiencies responding to extreme events are found

Open access

Hydraulics of Channelized Flow in Ice‐Supersaturated Debris: 1. Rock Glacier Hydrology in Alpine Glacial‐Periglacial Systems

  •  13 February 2025

Key Points

  • Water flowing through active rock glaciers is concentrated along a network of channels on top and within their frozen core

  • Flow along the channels is rapid, turbulent, and subject to substantial frictional resistance

  • Effective heat transfer along the channels drives the expansion of channel networks and amplifies their hydrologic connectivity

Open access

A Novel Topography‐Based Approach for Real‐Time Flood Inundation Mapping

  •  13 February 2025

Key Points

  • Proposed a novel Topography-based approach for Real-Time Flood Inundation Mapping (TOPFIM)

  • TOPFIM adapts to river segments and allocates flood volume based on topographical features by considering the water volume constraints

  • TOPFIM has higher computational efficiency with accuracy approximating to hydrodynamic model

Open access

Reinforcement Learning of Multi‐Timescale Forecast Information for Designing Operating Policies of Multi‐Purpose Reservoirs

  •  12 February 2025

Key Points

  • Multi-timescale hydro-meteorological forecast information helps in multi-purpose reservoir operations

  • A new methodology is proposed to learn the most valuable information from multiple forecasts and jointly design operating policies

  • With the available operational products, more skillful short-range lead times are preferred to ideally more informative extended-range ones

Open access

Combining Local Head Differences and Topography‐Driven Groundwater Flow Reveals Gaining and Losing Patterns in Stream Networks

  •  12 February 2025

Key Points

  • A method was developed to estimate surface water levels along the stream network by correcting a digital elevation model with 25 m resolution

  • Combining head gradients and topographic analysis reveals catchment-scale patterns and uncertainties in stream gains and losses

  • About 42% of streams indicate locally losing conditions despite being in a topographical discharge zone

Open access

Evaluating the Performance of Sentinel‐1 SAR Derived Snow Depth Retrievals Over the Extratropical Andes Cordillera

  •  12 February 2025

Key Points

  • We derived 4 years of snow depth maps at 1 km2 over the Andes mountains with Sentinel-1 SAR and other globally and freely available data

  • Snow depth retrievals perform best over sites with negligible evergreen forest cover and in deeper snow

  • Snow depth is overestimated for Tundra and Prairie snow class sites, whilst Maritime is unbiased

Open access

Quantification of Carbopeaking and CO2 ${\text{CO}}_{2}$ Fluxes in a Regulated Alpine River

  •  12 February 2025

Key Points

  • Flow regulation in an Alpine river affects the spatiotemporal variability and drivers of CO2 fluxes

  • Diel metabolism and carbonate buffering sustained by lateral inflows dominate CO2 dynamics in the residual flow reaches

  • Intense and localized peaks in CO2 concentration and evasion rate are observed downstream of the hydropower outlets during hydropeaking

Open access

Modeling of Low‐Velocity Non‐Darcian Flow With Nonlinear Consolidation in a Leaky Aquifer System Induced by a Fully Penetrating Confined Well

  •  12 February 2025

Key Points

  • We develop a model that describes low-velocity non-Darcian flow with nonlinear consolidation in a leaky aquifer system

  • Characteristics of aquitard consolidation influenced by nonlinear consolidation and low-velocity non-Darcian flow are investigated

  • The influences of various factors on the differences in results, with and without considering consolidation effects, are analyzed

Open access

Direct Observations of Solute Dispersion in Rocks With Distinct Degree of Sub‐Micron Porosity

  •  12 February 2025

Key Points

  • X-ray computed tomography and positron emission tomography applied in a multimodal imaging approach to study transport in rock cores

  • Spreading and mixing are independently quantified from pulse tracer tests and correlated to distinct forms of subcore-scale heterogeneity

  • When solely calibrated against the breakthrough curve, 1D transport models cannot accurately describe internal concentration profiles

More articles
Open access

A Transdisciplinary Review of Deep Learning Research and Its Relevance for Water Resources Scientists

Key Points

  • Deep learning (DL) is transforming many scientific disciplines, but its adoption in hydrology is gradual
  • DL can help tackle interdisciplinarity, data deluge, unrecognized linkages, and long-standing challenges such as scaling and equifinality
  • The new field of AI neuroscience opens up many opportunities for scientists to use DL as an exploratory tool for scientific advancement

Open access

MERIT Hydro: A High‐Resolution Global Hydrography Map Based on Latest Topography Dataset

Key Points

  • A global hydrography map was generated using the latest topography dataset
  • Near-automatic algorithm applicable for global hydrography delineation was developed
  • Adjusted elevation and river width layers consistent with flow direction map are provided

free access

A Rainfall‐Runoff Model With LSTM‐Based Sequence‐to‐Sequence Learning

Key Points

  • An hourly runoff model was developed using the LSTM sequence-to-sequence learning method for 24-hr predictions on USGS stations
  • The proposed model shows better performance than traditional data-driven models and is applicable to different watersheds
  • The advantages and limitations of seq2seq models and how this model structure could work on the rainfall-runoff modeling is presented

More articles
free access

Investigating the Propagation From Meteorological to Hydrological Drought by Introducing the Nonlinear Dependence With Directed Information Transfer Index

Key Points

  • Directed information transfer index was introduced in drought propagation study to build a new drought response time evaluation system for the first time

  • Trigger thresholds from meteorological to hydrological drought were determined by a drought propagation model

  • Sub-regions with smaller meteorological drought trigger thresholds had longer durations of hydrological drought events

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

free access

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

free access

Status of CO2 storage in deep saline aquifers with emphasis on modeling approaches and practical simulations

Key Points:

  • Carbon storage in deep saline aquifers is a viable carbon mitigation option
  • A wide range of modeling approaches can provide practical simulation results
  • Field-scale observations and modeling enhance system understanding

free access

A Method for Objectively Integrating Soil Moisture Satellite Observations and Model Simulations Toward a Blended Drought Index

Key Points

  • Develop a viable approach to validate the satellite soil moisture products
  • Translate model and satellite soil moisture into useful information for drought monitoring
  • An objective blended drought index is recommended

Open access

Global Groundwater Modeling and Monitoring: Opportunities and Challenges

Key Points

  • A global groundwater framework is needed to address critical gaps in our understanding and predictive capacity of the hydrologic cycle

  • We envision a framework that will combine observations and models to provide spatially and temporally continuous groundwater information

  • The proposed framework could improve predictability in existing models and provide valuable new information for water management

Plain Language Summary

Groundwater is an important part of the water cycle but we are still working on the best ways to include it in global models. This study provides an overview of the state of the science for groundwater modeling and outlines a road map for what is needed to improve global groundwater models.

Open access

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

Open access

Remote Sensing of Groundwater: Current Capabilities and Future Directions

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, Interferometric Synthetic Aperture Radar, Global Navigational Satellite System, lidar altimetry, and Airborne Electromagnetic Systems can yield indirect yet valuable information about groundwater

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

free access

ChatGPT in Hydrology and Earth Sciences: Opportunities, Prospects, and Concerns

Key Points

  • Large language models (LLMs) such as ChatGPT, are new technological tools that might fundamentally change academia

  • ChatGPT can assist in academic writing but should not be relied on as the only source of information in hydrology and Earth Science studies

  • Authors should exhibit transparency in their utilization of LLMs and uphold ethical responsibility

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