Application of Remote Sensing and Geographic Information System for Soil Erosion Assessment in Huay Nam Rit Watershed, Uttaradit Province

Abstract

The aim of this study was to assess the distribution and map the geomorphology and land use effects on soil erosion in the Huay Nam Rit watershed, Uttaradit province. The study integrated Landsat-5 TM imagery to analyze land use with a supervised classification maximum likelihood model, based on indices identified from training areas, with a Universal Soil Loss Equation (USLE) model for estimating onsite erosion by Geographic Information System (GIS). The study was performed on a grid size of 30 × 30 m producing a 1655.820 × 1655.820 m or 274.170 km² system.

The results of study indicated that land use in the Huay Nam Rit watershed can be divided into 10 land use types namely, hill evergreen forest, mixed generation deciduous forest, mixed deciduous forest, natural regeneration forest, banana orchard, paddy field, teak forest plantation, abandoned field crop, community, and water source. The evaluation of soil erosion in the watershed indicted that the rate of total soil erosion was slight (0.998 t/ha/year). However, most of the watershed area was covered with mixed deciduous forest which can produce covered soil erosion at an extremely severe rate (75.656 t/ha/year; 27.595 %), as this type has sparse forest where the soil is easily detached and transported by rainfall and runoff. However, the community land use type had soil erosion that was rated as slight (0.004 t/ha/year) due to its more gentle slopes, with the majority being on a plain.

Keywords: Remote Sensing System, Geographic Information System, Soil Erosion