Analysis of Surface Runoff and Remote Sensing Data to Identify Flood Potential in Simbang Sub-Watershed

Abstract

Increased water runoff due to land use change phenomena has triggered flooding events. The objective is to identify flood potential in Simbang Sub-Watershed in Maros Regency using rational methods and remote sensing data. Potential flood hazards were analyzed using the weighting method with the parameters NDVI, MNDWI, NDSI, rainfall, and annual flow coefficient. The highest debit of runoff occurred in 2017, with a value of 113.36 m3/s, while the lowest occurred in 2019, with a value of 63.91 m3/s. The NDVI value is 0.37–1 with high vegetation covering an area of 3,089 ha, while the low-very low vegetation has value -0.03–0.25 with an area of 1,668 ha. The MNDWI value ranges from 0-0.33 with a moderate wetness level covering an area of 741 ha and an NDSI value ranging from -0.06–0.43 for bare land surrounding an area of 738 ha, which has an impact on reducing water catchment areas which can trigger an increase in surface water runoff discharge. The average rainfall is 2,965 mm/year, the area with low potential for flooding is 3,705 ha, and the area prone (moderate) to flooding is 1,450 ha. The rainfall factor is the main priority trigger for flood events with weight of 0.266, and the soil index is the lowest priority factor with weight of 0.145. Surface water runoff in the Simbang Sub-Watershed area makes a small contribution to the flood events that occurred in Maros Regency with an annual flow coefficient value of 0.23.