Evaluation of catchment hydrology and soil loss in non-perennial river system: a case study of Subarnarekha Basin, India

The climate of India reflects the instability and variability of the monsoon in the tropical regions of the country. Monsoon in India occurs annually, with variations in rainfall that adversely affect water resources, agriculture, and other regional conditions. The perception of the variability of the monsoon season is one of the critical problems in the field of atmospheric science. In the study area, the Subarnarekha river basin being non-perennial, exclusively depend on the monsoon to maintain its riverine flow. The variability and instability of the monsoon can significantly influence the hydrological parameters (erodibility and discharge) of this river basin. Therefore, it requires significant water resource management through the assessment of the hydrological processes. It is crucial to assess both the runoff response and soil loss in the drainage basin to evaluate the hydrological conditions of the drainage basin. The soil and water assessment tool (SWAT) is a hydrological model used in this study to simulate the discharge rate for runoff responses daily, monthly, and annual. A simulation of a similar kind has been carried out regarding the soil loss to estimate the amount of erosion before and after significant rainfall events in the study area. The study emphasizes the SWAT model and its efficacy in assessing water flow through ungauged channels or rivers. The present study showed that the SWAT model successfully characterized the role of the Subanarekha Basin’s monsoon-driven hydrological processes leading to erosion.