Decomposing impact of climate change and land surface alterations on catchment hydrology in Eastern Himalaya

Abstract

Climate change is intensifying water challenges in the Eastern Himalayas. Bridging climate change and water demand is vital, especially in India’s ungauged Himalayan catchments. The proposed novel method aims to differentiate climate change and anthropogenic activity impacts on catchment hydrology. In this study, evaporative demand was assessed by coupling SWAT and Budyko framework at the micro-watershed scale for understanding climate and surface changes in local hydrology. The coupled model considers climate parameters through SWAT to decompose the impacts of climate change and anthropogenic activities on watershed hydrology. The Budyko framework depicted the relationship between precipitation, evapotranspiration (ET), and potential evapotranspiration (PET) resulting in partitioning evaporative demand into green and blue ET. Parameters like d-statistics, responsivity, and elasticity assessed the buffer capacity of catchments against climate change. The study unveiled catchment characteristic (ω) values within the range of 1.70–1.56 from 2005 to 2030, indicative of a discernible shift in hydrological patterns attributed to changes in land use land cover (LULC) and climate variables. The investigation underscored the significant impact of LULC changes, manifesting as a reduction in snow and glacier cover alongside an augmentation in blue ET. The variation in precipitation, LULC, PET, and temperature were identified as primary influencers on hydrological regimes, rendering watersheds increasingly susceptible to climatic variations. Six catchments are unable to cope with or buffer against climate change and have low coping capacity. The study emphasizes the exigency to water resource management in ecologically delicate Eastern Himalayan ecosystem. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.