The impact of soil erosion on sedimentation/silting and decreasing water quality in oxbow lake, Grogol Sub-district, Sukoharjo District

Land use changes that are not under its designation (carrying capacity and capacity) will cause environmental degradation such as erosion. Erosion that occurs, in general, will result in a reduction in soil fertility, a reduction in soil volume, and may result in silting/sedimentation and a decrease in water quality due to an increase in Total Suspended Solid (TSS) levels. The purpose of this study was to determine the Erosion Hazard Level (EHL) that occurred around the oxbow lake and the impact caused by the erosion on the sustainability of the function of the oxbow lake. The methods used in this research are field survey and mapping methods, laboratory analysis methods, and spatial analysis methods on topography and bathymetry as well as Sentinel Satellite Imagery to find out the estimated size of the existing TSS. Erosion rate measurements were carried out using the erosion measuring stick method to measure soil loss over a certain time. Based on the results of the study, it was found that there were two TBE in the study area, including areas with Very Heavy TBE (SB) due to having soil solum > 90 cm and erosion of 653.01 tons/ha/yr. (PME 1), 581.34 tons/ha /yr. (PME 2), and 1022 tons/ha/yr. (PME 3) (> 480 tons/ha/yr.); and areas with heavy TBE (B) due to having soil solum > 90 cm and erosion of 387.80 tons/ha/year (180 - 480 tons/ha/year). The impact of erosion can also result in silting/sedimentation in the oxbow lake so that it can indirectly lead to a reduction in oxbow lake capacity/reservoir and an increase in the TSS parameter which is expected to continue due to an increase in the trendline both in the amount of rainfall and the average rain that occurred in 3 years. and in 2022 (January – June).