Assessment of soil erosion and landslides susceptibility based on hydrophysic soil properties in Karangkobar catchment, Banjarnegara, Indonesia

Landslides and erosion are highly influenced by soil properties. Soil texture, structure, particle density, bulk density, and porosity are the properties which correspond to infiltration rates. This study aimed to assess soil erosion rate and landslide in upland of Karangkobar catchment and to explore its correlation to hydrophysic soil properties. Material used in this study were topographical maps, land use maps, administrative maps on scale 1:25000, and soil samples. An unit land map was created by overlying topographic, landuse, and administrative maps. This study found 16 unit lands. Soil sampling and infiltration test were conducted in every unit land. Infiltration test adopted double ring infiltrometer test, while Horton's formula was applied to determine the value of infiltration capacity. Soil hydrophysic properties in catchment area Karangkobar: texture loam, granular structure, bulk density 0.62-1.09 g cm^-3, particle density 1.83-2.47 g cm^-3, and infiltration capacity 1.5 cm hour^-1-67.9 cm hour^-1. Erosion rate was 2 mm year^-1 with the potential landslides classified as high. Soil hydrophysic properties which have a strong correlation to erosion was bulk density (r = 0.517) and potential landslides was infiltration rate (r = 0.641).