Evaluation of Soil Loss and Sediment Yield Based on GIS and Remote Sensing Techniques in a Complex Amazon Mountain Basin of Peru: Case Study Mayo River Basin, San Martin Region

Abstract

This study aims to estimate the average annual rate of soil loss by rainfall in terms of spatial distribution and sediment rate using RUSLE and GIS techniques. Additionally, remote sensing and available soil property information are applied for erosion analysis. The work reveals a very severe type of soil erosion, with the highest mean rate in the steep areas. Annual mean erosion in many parts of the basin is in the range of 0 to 9237.0 t/km2/year with an average of 403 t/km2/year. Approximately 45% (in the upper basin) of the total area has moderate to high soil loss by water, especially in five catchments, namely Serranoyacu, Naranjos, Naranjillo, Yuracyacu, and Tonchima at 886.8 t/km2/yr, 985.1 t/km2/yr, 691.3 t/km2/yr, 567.3 t/km2/yr, and 506.9 t/km2/yr, respectively. Catchment-wise soil loss estimates suggest that these areas are experiencing much higher soil loss in comparison to others; hence, these catchments are prioritized for soil conservation efforts. Sediment rate assessments indicate high sediment deposition along the flow direction of the mainstream of the catchment; in the upper Mayo part, the highest sediment rates are in Yuracyacu, Serranoyacu and Tonchima. Finally, the parts most vulnerable to increased erosion rate are the central part of the basin, which indicates progressive sediment deposition.