The Role of Slope Position on Soil Erosion Acceleration in The Tertiary-Quaternary Volcanic Landscape

Abstract

Identifying the predisposing factors of soil erosion acceleration is an intriguing worldwide subject since each site has unique characteristics. Here, we aim to analyze the influence of slope position on soil erosion acceleration in The Tertiary-Quaternary Volcanic Landscape. Soil erosion was measured through a volumetric approach. Soil properties analysis included soil texture, aggregate stability, permeability, bulk density, particle density, porosity, and organic matter. Soil properties were purposively assessed at 18 sampling points. This study showed that the slope position determined soil erosion and characteristics. Typically, the dominant processes were soil aggregate destruction due to raindrops and transportation by runoff on the upper slope. In addition, greater flow volume and higher flow erosivity are the ultimate consequences of flow accumulation from the upper slope. Those processes resulted in the even distribution of 14,6 ton/ha rill erosion at the peak of the rainy season. Surprisingly, the most significant soil erosion process on the middle slope was runoff scouring, which resulted in 4.7 tons per hectare of gully erosion at some concave spots. Furthermore, the overpowering mechanism on the lower slope was the debris deposition. Although the soil parameters on the middle slope were good, soil erosion developed because the overland flow reduced soil porosity and permeability. Since gully and rill erosion are the primary causes of soil loss, the slope position directly impacts the volume and direction of overland flow. Finally, controlling the soil erosion rate should be concentrated on rill and gully erosion. Communities and stakeholders can use the findings to implement sustainable land management, particularly in regions with comparable typologies.

Keywords

• soil erosion
• slope position
• erosion acceleration
• volcanic landscape