Assessing soil erosion risk in karst area using fuzzy modeling and method of the analytical hierarchy process

Abstract

Soil erosion is a geo-ecological problem in Southwest China, which can result in karst rocky desertification when it is very serious. The grade delineation of soil erosion risk can be used as a guide for controlling regional and hierarchical soil erosion, and provide scientific references for restraining rocky desertification. Chaotian Town, an area of Karst Mountains and hills in Guilin, northeast part of Guangxi Zhuang Autonomous Region, China, was chosen as the study area. Settlement buffer, roadway buffer, lithology, slope, elevation, and aspect were selected as the main indicators of soil erosion in the karst area. After the indicators were scored by fuzzy modeling, the potential risk of soil erosion was quantified using indicator-weight union method. Five grades of soil erosion risk were delineated based on Geographic Information System. The grades of minimal, low, medium, high, and extreme soil erosion risk accounted for 1.62, 19.46, 52.35, 24.86, and 1.71 %, respectively. As a whole, the soil erosion risk was moderate, because the proportion data of different grades of soil erosion risk were a normal distribution, and about 52.35 % of the study area was in the medium grade. Soil erosion risk was higher in the southeast of the study area and lower in the northwest. Obvious variances have been found in the grade distribution of soil erosion risk, corresponding to different indicators.