Abstract
Pengga Dam is a water resource in the Pelambik Village area, Southwest Praya, Central Lombok, West Nusa Tenggara. This dam experienced sedimentation problems caused by land erosion, threatening its helpful life. Preventing the decline in the useful life of the dam can be done by predicting the amount of erosion that occurs in the dam's catchment area. The erosion rate can be estimated and analyzed using the Modified Soil Loss Equation (MUSLE) method using ArcGIS 10.8 software. The MUSLE method consists of several factors that influence its analysis; there are surface runoff factor (R), soil erodibility factor (K), length and slope factor (LS), land use factor (C), and erosion control-practice factor which are analyzed into a layout based on the catchment area of Pengga Dam. Using the erosion value, the sedimentation of Pengga Dam is calculated based on the Sediment Delivery Ratio (SDR) using the Boyce (1975) method and the Menhut (2005) method. The results of data analysis show that the erosion rate in the Pengga Dam Catchment Area (CA) is 38456.98 tons/year with an eroded catchment area of 19537.56 ha. Based on the Brune and Churchill graphs, the trap efficiency value of Pengga Dam is 96%. Therefore, the sedimentation of Pengga Dam is 1583.936 m³/year using the Boyce method and 2093.06 m³/year using the Menhut method. From the results of this erosion and sedimentation analysis, it is hoped that erosion at Pengga Dam can be predicted and controlled in the future so that it does not have a harmful impact.