Abstract:

Terrain is an important controlling factor affecting the process of soil erosion and plays an important role in the evaluation of soil erosion. In this paper， based on the expression of terrain relief， the terrain index was constructed， and the soil loss formula based on terrain index was established by combining rainfall erosivity and vegetation coverage. The temporal and spatial variation characteristics of soil erosion from 1985 to 2018 in the loess area of Ten Turbutries sandstone in the north of Ordos City， Inner Mongolia Autonomous region were analyzed. The main results are as follows： （1） the soil erosion modulus in the study area showed no significant decreasing trend for many years， and the average erosion modulus was 22.34 t·hm^-2·a^-1. The soil erosion modulus was the highest in 1985 and the lowest in 2000， and showed a downward trend from 1985 to 2000 and an upward trend from 2000 to 2018. （2） The average soil erosion area for multi-year was 2 956.07 km². The soil erosion area was the largest in 1985 at 4 047.14 km²， accounting for 83% of the total area； it was the smallest in 2000 at 2 153.67 km²， accounting for 44%. There were mainly light and moderate erosion intensity grades in the study area from 1985 to 2000， and there were mainly slight and mild erosion intensity grades from 2000 to 2018. （3） The spatial distribution pattern of soil erosion had remained basically the same over the years. The comprehensive index of soil erosion was increasing from west to east， and the soil erosion in the east was greater than that in the west. Among them， Muhaergou had the largest soil erosion comprehensive index and Maobula was the smallest. （4） There was no significant difference in the estimation of soil erosion modulus and area between Terrain Soil Loss Equation and Universal Soil Loss Equation （P>0.05）.

Key words: USLE, terrain index, comprehensive index of soil erosion, loess area of sandstone