AHP GIS-Based Gully Erosion Susceptibility Modelling in Tropical Volcano Environment

Abstract

Gully erosion is the most destructive form of erosion and contributes significantly to the accumulation of water sediment in an area. This study aims to map the gully erosion susceptibility in the Kodil watershed, Central Java, Indonesia. The base data used in this study are from Sentinel-2 with a resolution of 10 m and DEMNAS (National Digital Elevation Model of Indonesia) with a resolution of 8 m. The Analytical Hierarchy Process (AHP) was used to assess the weight of each parameter that influences the gully erosion susceptibility. Overall, there were ten parameters used in this study, namely a) elevation (m); b) slope gradient (0); c) slope aspect; d) slope curvature; e) topographic wetness index; f) distance from the river (m); g) distance from the road (m); h) land use; i) soil texture; and j) soil aggregate. An accuracy test used the AUC (Area under Curve). The results of spatial data analysis proved that 855 ha (6.34%) of land in the Kodil DAS has a high susceptibility to gully erosion. Testing with AUC shows that the AUC training value was 0.742, the AUC test was 0.737, and the accumulative AUC value was 0.73, so the model results fall into the good category. The novel aspect of this study is the use of texture and soil aggregate parameters that have never been studied before. The decision to employ soil parameters is inextricably linked to the characteristics of the research site, which has extremely thick soil layers with high clay content. The gully erosion susceptibility model helps plan the development of land resources in its sustainability aspect. Keywords: gully erosion, analytical hierarchy process, susceptibility modeling, tropical volcano environment. https://doi.org/10.55463/issn.1674-2974.50.2.20