Projecting water demands under various socioeconomic scenarios in the upper Jhelum basin, Indus using WEAP model

The Upper Jhelum Basin (UJB), a glacier-fed, critical sub-basin of the Indus River system in Kashmir, India, is undergoing rapid socioeconomic transitions in the Himalayan region, with population nearly tripling from 0.67 to 1.96 million and horticultural land expanding fourfold from 165 to 641 km² between 1981 and 2020, fundamentally restructuring the basin’s sectoral water demand. Despite its hydrological and socioeconomic significance as a key lifeline of the Kashmir Valley and a critical component of the Indus basin, no comprehensive long-term, multi-sector water demand projection has previously been developed for the UJB, representing a critical gap in regional water resource planning that this study directly addresses. This study employs the Water Evaluation and Planning (WEAP) model calibrated against observed streamflow (1981–1990) and validated over an independent period (1991–2010) to simulate water supply and demand dynamics across five glacier-fed sub-watersheds of the basin, namely Lidder, Kuthar, Bringi, Sandran, and Vishav, under five long-term socioeconomic scenarios extending up to 2100, integrating four decades of satellite-derived land use and land cover data and demographic records as model inputs. The results reveal a significant restructuring of sectoral water demand between 1981 and 2020: annual agricultural water demand declined by 66% from 716 Mm³ to 246 Mm³, driven by a reduction in cultivated land from 991 to 361 km²; horticultural water demand rose sharply from 110 Mm³ to 434 Mm³, corresponding to the fourfold expansion of orchard land; and domestic water consumption increased from 74 Mm³ to 245 Mm³, reflecting population growth and expanding piped water infrastructure. Scenario projections from 2021 to 2100 indicate cumulative domestic water demand of 26,547 Mm³ under the reference scenario, with 494 Mm³ unmet demand; rising to 42,566 Mm³ with 3,323 Mm³ unmet under high population growth, and to 58,230 Mm³ with 7,336 Mm³ unmet when combined with high living standards; while low and very low population growth scenarios project 21,333 Mm³ (198 Mm³ unmet) and 19,614 Mm³ (142 Mm³ unmet), respectively. This 52-fold span in cumulative unmet domestic water demand from 142 to 7,336 Mm³ constitutes the first scenario-based planning envelope for infrastructure investment and population management decisions in the UJB, and underscores the dominant role of demographic growth and land use change as primary drivers of the long-term water demand trajectories in glacier-fed Himalayan sub-basins.