National assessment of soil erosion and its spatial patterns in china

Abstract

The spatial patterns of soil erosion (SE) are an important part of ecological security patterns and critical to erosion control. We assessed the SE and its spatial distribution in China based on geographic information system (GIS) and spatial data sets using the Universal Soil Loss Equation (USLE). The soil erosion area (SEA) and soil erosion amount (SEM) totaled 173.06 million ha and 8.87 billion Mg, respectively, with an average soil erosion rate (SER) of 9.39 Mg·ha−1·yr−1. Slight erosion dominated from the aspect of SEA, whereas extreme erosion contributed the most in terms of SEM. Spatial heterogeneity in soil erosion was obvious in China, with heavily eroded areas mainly concentrated in the Loess Plateau, the Three Gorges reservoir area, and the hot, dry valley of the Jinsha River. Regionally, the provinces of Tibet, Sichuan, Yunnan, Xinjiang, Inner Mongolia, Gansu, Shaanxi, Shanxi, Guizhou, and Guangxi, and the basins of the Yangtze River, Yellow River, and southwestern rivers made a large contribution to the SEA and SEM. Geographically, soil erosion increased, then decreased with increasing slope and elevation. Slopes of 15–25° and 8–15° and elevations of 1000–2000 m were the most seriously eroded. Cropland and grassland ecosystems were major sources of SE, with their SEA and SEM accounting for 64.44% and 77.96% of the total. This study revealed the current situation and spatial characteristics of SE in China on the national scale, which can serve as a scientific basis for regional SE control and decision‐making policy.