Climatic Variability and Surface Water Dynamics in a Hilly Region of Northeast India: Implications for Soil and Water Conservation in Longding District, Arunachal Pradesh

Abstract

Abstract: Climatic variability plays a critical role in influencing soil moisture regimes and surface water availability in hill ecosystems of Northeast India. This study examines the impact of long-term variations in rainfall and temperature on surface water dynamics in Longding District, Arunachal Pradesh. Multi-temporal climate datasets derived from WorldClim were analyzed for the years 1990, 2000, 2010, 2020, and 2024 to assess changes in precipitation and temperature patterns. Normalized Difference Water Index (NDWI) was computed using satellite imagery to evaluate spatial variations in surface water distribution across corresponding periods. The results indicate a general decline in annual precipitation and a gradual increase in temperature over the study period. NDWI analysis reveals noticeable spatial fluctuations in surface water expression, reflecting the hydrological response of the region to changing climatic conditions. The combined effect of reduced rainfall and rising temperature suggests increased evapotranspiration losses and potential stress on soil moisture retention and groundwater recharge. These changes have direct implications for rainfed agriculture and watershed stability in the district. The study highlights the importance of integrating climatic assessment with remote sensing-based water indices to support soil and water conservation planning in hill regions.