Analysis of Surface Runoff in the Beratan Lake Rain Catchment Area

Abstract

Rainwater infiltration and surface runoff are fundamental hydrological processes that directly affect water availability, watershed health, and flood risk. Understanding runoff dynamics is essential for designing effective water resource management strategies, particularly in sensitive catchment areas. This study analyzes the quantity of surface runoff in the Lake Beratan catchment, located in Baturiti Subdistrict, Tabanan Regency, Bali Province. A quantitative approach was employed using both primary and secondary hydrological data, with runoff discharge estimated through the Thornthwaite-Mather method. The results indicate notable temporal variability, with the highest monthly average runoff recorded in February at 1.2921 m³/second, while the lowest occurred in September at 0.0303 m³/second. The annual average runoff was calculated at 5.6663 m³/second. These findings highlight the seasonal dependence of runoff on rainfall patterns, which has significant implications for local water management, agricultural planning, and flood control. The study concludes that accurate runoff estimation provides a scientific basis for sustainable watershed management in the Lake Beratan area. It further suggests that integrating hydrological monitoring with adaptive water management policies is essential to balance ecological preservation, water supply stability, and community resilience.