SWAT-Based Assessment of Land Use Dynamics on Precipitation–Discharge Interactions in the Sagileru Basin, India
Abstract
Hydrological variability in river basins is strongly influenced by LULC changes, particularly in tropical regions where rapid forest transformation and agricultural expansion alter rainfall–runoff processes. Understanding how these dynamic land surface changes affect precipitation–discharge relationships is essential for sustainable water and soil resource management. This study examines the impact of multi-temporal LULC changes on precipitation–discharge interactions in the Sagileru Basin, a tropical sub-catchment of the Pennar River basin, Andhra Pradesh, India. The SWAT hydrological model was implemented for the period 1990–2020 using topography, soil characteristics, daily meteorological data, and dynamic LULC datasets from 2000, 2010, and 2020. Model calibration and validation were carried out using SWAT-CUP (SUFI-2) with fourteen sensitive hydrological parameters and observed monthly discharge data. Model performance was evaluated using the coefficient of determination (R²), Nash–Sutcliffe efficiency (NS), and percentage bias (PBIAS). In addition, precipitation–discharge correlations were analyzed at the sub-catchment scale under different LULC scenarios. The model showed good performance, achieving R² and NS values of approximately 0.8 and low PBIAS (<1.0) during both calibration and validation periods. Results indicate that forest-dominated sub-catchments exhibit stronger precipitation–discharge correlations, whereas agricultural expansion and wasteland formation reduce correlation values by 0.12–0.30 in selected sub-catchments. Compared to similar SWAT-based studies conducted at basin scales, this study highlights pronounced spatial variability at the sub-catchment level. The integration of dynamic LULC analysis with long-term precipitation–discharge relationships provide valuable insights for prioritizing soil conservation and water management strategies in tropical watersheds.Received: 2025-12-05 Revised: 2026-04-07 Accepted: 2026-05-21 Published: 2026-08-12