Sediment export estimation from the catchment area of Lake Rawapening using InVEST model

Abstract

Sedimentation is one of the main problems of the fifteen priority lakes in Indonesia, including Lake Rawapening. It has adverse impacts on lake, such as siltation that contribute to eutrophication and reduce the lake’s lifetime. Therefore, reducing sedimentation rate was set as one of the super-priority programs of the Lake Rescue Movement. Information on the spatial distribution of sediment export becomes important to implement the program effectively. This study aims to estimate the magnitude and the spatial distribution of sediment export from the catchment area of Lake Rawapening. The analysis was based on the Sediment Delivery Ratio sub-model. The results indicated that the total sediment export from the catchment area of Lake Rawapening is 501,628.6 tons/year. The largest export of sediment came from Galeh Sub-sub watershed, i.e., 161,091.7 tons/year (32.1% of the total sediment). However, Legi Sub-sub watershed has the highest average of sediment export per hectare, i.e., 42.9 tons/ha. High sediment export generally occurs in the upstream area with very steep slope, high rainfall, and dominated by dryland agriculture and vegetable farm land. Thus, efforts to reduce sediment export to Lake Rawapening should be focused on the hot-spot area, such as the upstream area of Legi Sub-sub watershed.

Lake and Stream Buffer Zone Widths' Effects on Nutrient Export to Lake Rawapening, Central Java, Indonesia: A Simple Simulation Study

“…It has an area of about 27,130 ha (Nugroho, 2017;Piranti, 2019). More information on Lake Rawapening can be found in (Nugroho, 2022a(Nugroho, , 2022b. A map of the study area is presented in Figure 1.…”