Sahoo et al. (2026) An integrated basin-scale indicator framework for assessing spatial imbalance in water availability and use: Evidence from India

Identification

• Journal: Ecological Indicators
• Year: 2026
• Date: 2026-10-24
• Authors: Debi Prasad Sahoo, Kaushal Kishor Garg, Aiendrila Dey, Nagarjuna Reddy, Sourav Roy, Israr Majeed, Niranjan Padhan, Nagaraju Budama, Venkataradha Akuraju, K. H. Anantha, Ramesh Singh, Himanshu Pathak
• DOI: 10.1016/j.ecolind.2026.115743

Research Groups

• International Crops Research Institute for Semi-Arid Tropics (ICRISAT), Patancheru, India

Short Summary

This study developed an integrated basin-scale indicator framework to comprehensively assess water availability, utilization, groundwater stress, residual water, and basin-development status across 22 major river basins of India. The framework revealed significant spatial heterogeneity, with approximately 85% of the national river-basin area experiencing critical to very critical water stress, largely influenced by increasing human interventions such as groundwater-dependent irrigation and reservoir sedimentation.

Objective

• To quantify basin-scale water availability and rainfall partitioning across major river basins by examining the allocation of rainfall among major hydrological components.
• To assess the extent of water utilization across surface water and groundwater systems in relation to available resources.
• To identify basin-level imbalances by distinguishing between withdrawn and residual water components, thereby characterizing patterns of water stress, resource development, and remaining water within the basin accounting framework.

Study Configuration

• Spatial Scale: 22 major river basins of India.
• Temporal Scale:
  • Rainfall: Long-term average (30 years) from 1992 to 2022.
  • Reservoir sedimentation: Surveys from 2000, 2010, and 2023.
  • Land use/land cover: 2015 and 2024.
  • Groundwater: Assessment years 2017 and 2024.
  • Overall: Synthesis of the most recent nationally available information, not a strictly synchronous water-balance assessment.

Methodology and Data

• Models used: An integrated basin-scale indicator framework based on water balance principles, which synthesizes nationally reported datasets rather than employing process-based hydrological models.
• Data sources:
  • India Meteorological Department (IMD): Gridded rainfall data (0.25° × 0.25° spatial resolution).
  • Central Water Commission (CWC): Average Annual Water Resources Potential (AAWRP), surface water utilization statistics, dam storage capacity, and reservoir sedimentation data.
  • Central Ground Water Board (CGWB): National Compilation on Dynamic Ground Water Resources of India for groundwater recharge and abstraction (district-scale, aggregated to basin-scale).
  • National Remote Sensing Centre (NRSC), ISRO: National Land Use/Land Cover (LULC) database (56 m × 56 m spatial resolution).

Main Results

• At the national scale, average annual rainfall of 1141 mm generates about 611 mm of basin water resources (54% of rainfall), with 211 mm utilized as surface water and 86 mm as groundwater, leaving approximately 314 mm (51.4%) as residual water. The national Groundwater Stress Index (GSI) is 0.64, indicating critical groundwater utilization.
• Significant spatial heterogeneity exists: high-rainfall basins (e.g., Brahmaputra, Barak) show large residual-water fractions (>75%) and low utilization, while basins like Krishna, Cauvery, Pennar, and Indus exhibit intensive utilization, elevated groundwater stress, and limited residual water. The Ganga basin is identified as a closing basin with intensive conjunctive use.
• Human interventions increasingly influence water resources: cumulative reservoir storage losses due to sedimentation increased from 9.5% in 2000 to 16.6% in 2023. The expansion of irrigated agriculture has become predominantly reliant on groundwater, with tube-well irrigation increasing from less than 5 million hectares (Mha) in the 1950s to approximately 35–40 Mha by 2022–2023.
• An area-based assessment indicates that approximately 85% (ranging from 78% to 86% across sensitivity scenarios) of the national river-basin area falls under critical to very critical water-stress conditions, with only about 15% remaining under safe to very safe conditions.
• Environmental-flow sensitivity analysis shows that under a 10% environmental flow requirement (EFR) scenario, two basins fail to meet the threshold, while under a more protective 30% EFR scenario, eight basins become constrained, primarily affecting highly developed river systems.

Contributions

• Developed and applied an integrated basin-scale indicator framework that unifies rainfall partitioning, groundwater processes, storage infrastructure, water utilization, land-use dynamics, and environmental-flow sensitivity within a common water-accounting structure.
• Addressed the limitations of fragmented national-scale water assessments by providing a comprehensive and consistent understanding of basin-development status and water-resource conditions across India.
• Demonstrated a transparent and operationally relevant approach for integrated basin-scale water assessment using readily available national datasets, offering a complementary perspective to model-based studies.
• Provided a practical basis for classifying river basins into "open," "closing," and "closed" categories based on a Basin Development Index (BDI), supporting evidence-based water-resources planning and prioritization.
• Highlighted the increasing influence of long-term human interventions (e.g., reservoir sedimentation, groundwater-dependent irrigation) on basin-scale water resources beyond hydro-climatic variability.

Funding

• CGIAR Science Program on Multifunctional Landscapes (MFL) (partially supported staff time of the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) team).

Citation

@article{Sahoo2026integrated,
  author = {Sahoo, Debi Prasad and Garg, Kaushal Kishor and Dey, Aiendrila and Reddy, Nagarjuna and Roy, Sourav and Majeed, Israr and Padhan, Niranjan and Budama, Nagaraju and Akuraju, Venkataradha and Anantha, K. H. and Singh, Ramesh and Pathak, Himanshu},
  title = {An integrated basin-scale indicator framework for assessing spatial imbalance in water availability and use: Evidence from India},
  journal = {Ecological Indicators},
  year = {2026},
  doi = {10.1016/j.ecolind.2026.115743},
  url = {https://doi.org/10.1016/j.ecolind.2026.115743}
}