COMMUNITY PARTICIPATION IN DETERMINING RUNNOUT COEFFICIENT AS AN EFFORT TO REDUCE FLOOD VOLUME IN TEWAH VILLAGE

The Rational method is one of the simple hydrological modeling to estimate the discharge of a watershed, and one of the important factors in the rational method is the runoff coefficient (C). The purpose of this study is to analyze the results of the Rational method discharge estimation using the runoff coefficient value that is tested and analyzed based on the parameters of community participation in the use of its land use. Analysis of the planned flood discharge using the Rational method, followed by analysis of the runoff coefficient value (C), analyzed using the SWOT analysis method, which is the basis for determining the parameters in simulating the runoff coefficient value (C) to reduce the magnitude of the planned flood discharge. The results of the study showed that the form of community participation in reducing the risk of flood disasters in the Tewah Village area, especially in areas affected by flooding, was to change 40% of the built-up area/community settlements and 10% of the forest area/open land area to be converted into parks, as an effort to carry out the greening process and utilize residents' yards as rainwater catchment areas which produced the lowest C runoff coefficient value, namely 0.26, so it is assumed to reduce the planned flood discharge value by around 8% of the 2023 discharge.