An integrated basin-scale indicator framework for assessing spatial imbalance in water availability and use: Evidence from India

Understanding basin-scale water-resource dynamics is essential for sustainable water-resources planning and management. However, existing national-scale assessments often evaluate rainfall, surface water, groundwater, storage infrastructure, and land-use dynamics separately, limiting a comprehensive understanding of basin-development status and water-resource conditions. Therefore, this study developed an integrated basin-scale indicator framework to assess water availability, utilization, groundwater stress, residual water, and basin-development status across 22 major river basins of India using nationally reported datasets on rainfall, surface water, groundwater, reservoir storage, sedimentation, and land use. The proposed framework integrates rainfall partitioning, groundwater processes, storage infrastructure, water utilization, land-use dynamics, and environmental-flow sensitivity within a common water-accounting structure. At the national scale, average annual rainfall of 1141 mm generates about 611 mm of basin water resources, of which 211 mm and 86 mm are utilized as surface water and groundwater, respectively, while approximately 314 mm (51.4%) remains as residual water. Considerable heterogeneity was observed across river basins. High-rainfall basins such as the Brahmaputra, Barak, and west-flowing river systems of the Western Ghats exhibited large residual-water fractions (>75%, reaching nearly 100% in some basins) and relatively low utilization, whereas basins such as Krishna, Cauvery, Pennar, and Indus showed intensive utilization, elevated groundwater stress, and limited residual-water availability. The Ganga basin, despite receiving moderate rainfall (∼1020 mm), was identified as a closing basin characterized by intensive conjunctive use of surface water and groundwater.The analysis further demonstrated that India's water resources are increasingly influenced by long-term human interventions in addition to hydro-climatic variability. Progressive reservoir sedimentation increased cumulative storage losses from 9.5% in 2000 to 16.6% in 2023, while expansion of irrigated agriculture has relied increasingly on groundwater development. The area-based assessment indicated that approximately 85% (range ∼ 78–86% across sensitivity and threshold scenarios) of the national river-basin area falls under critical to very critical water-stress conditions, whereas only about 15% remains under safe to very safe conditions. The study demonstrates that basin conditions are governed not only by hydrological availability but also by groundwater development, storage infrastructure, land-use change, and water-utilization patterns. The proposed framework provides a transparent and operationally relevant approach for integrated basin-scale water assessment and can support evidence-based water-resources planning and prioritization in India and other regions facing fragmented water-information systems and increasing pressure on water resources.