The integration of remote sensing (RS) and geographic information systems (GIS) technologies in hydrology has become increasingly important, offering solutions to understand the complexities of surface water and groundwater dynamics and their environmental interactions. This integration serves as a valuable tool for improving natural resource management by facilitating the acquisition of spatially explicit data, crucial for assessing environmental changes and predicting future trends. Focusing on the Valapattanam River Basin, this study utilizes the Soil and Water Assessment Tool (SWAT) to investigate the spatio-temporal variability of streamflow. The efficiency of the model is confirmed through calibration (R2: 0.92, NSE: 0.87, PBIAS: 9.6) and subsequent validation (R2: 0.89, NSE: 0.85, PBIAS: 3.9) covering the period from 1997 to 2022. Spatio-temporal analyses of surface runoff and groundwater contribution to streamflow reveal distinct patterns within the Valapattanam River Basin. Downstream streamflow is notably influenced by groundwater, peaking between August and October, while surface runoff predominantly shapes upstream regions, especially from June to August. Additionally, the analysis highlights a temporal lag, indicating a one-month delay in groundwater contribution to streamflow. This study emphasizes the crucial role of spatio-temporal streamflow analysis in formulating effective water resource management strategies and strategic planning in the study area. Future research endeavors may explore further integration of advanced modeling techniques and additional data sources to address emerging challenges in hydrological management and environmental conservation.