Beyond traditional metrics: a comprehensive framework for blue and green water scarcity assessment in a changing climate

This study presents an integrated framework to assess blue and green water scarcity at sub-basins scale, by considering sectoral water demands and climate projections. The study proposes novel and improved indices for assessing scarcity in green water, i.e. Potential Green Water Scarcity (PGWS) index and the Potential Agricultural Water Scarcity (PAWS) index, which overcome the limitations of traditional indices by accounting for actual crop water deficits. The framework is demonstrated in the Upper–Middle Godavari basin. Results show substantial spatial variability in blue and green water resources, with projected declines in green water availability of up to 50% in some sub-basins. Persistent blue water scarcity (BWS >1) emerges in central and south-western regions, while PGWS indicates critical deficits of 400–600 ×106 m3 during summer months. The PAWS shows minimal Kharif stress but severe Rabi deficits (800–2000 ×106 m3), underscoring the need for targeted, climate-resilient water management strategies.