Land Conservation Practices Induced by Soil Loss Simulation with GIS in Loess Plateau, China

抄録

A typical small watershed (5.91km²) located in the Loess Plateau (Mizhi County, Shanxi Province, China) was selected for the trial study. The objective of this study was to quantify the amount of soil eroded under current land use and to predict soil loss according to different conservation measurements simulated with pc-ARC/INFO GIS (Geographical Information System) on the principle of the USLE (Universal Soil Loss Equation). Thematic maps of the watershed related to land use, soil, soil erosion, and land type were drawn from aerial photo field surveying, and the slope map was derived from DTM (Digital Terrain Model) analysis. The rill and interrill erosion region where most of the crops are planted was extracted from the watershed based on the concept of the division of geomorphological characteristics and erosive types.
Through overlaying of thematic maps, a distributive map unit was generated with an attached attributive data file that consists of all necessary information for soil loss quantification and land evaluation and planning. The amount of soil loss under present land use was calculated and used as the baseline for comparing soil loss under different conservation simulations. Land use planning was conducted with the methodology of linear planning, and it was dependent on the results of land quality evaluation and the possibility of economic development prediction in the village. The potential soil loss was evaluated and compared to simulations of other biological and engineering land conservation practices.
The results by computer simulation showed that both biological and engineering countermeasures can effectively protect soil against water erosion. However, the best approach was the combination of terrace engineering and the adjustment of land use pattern, which was based on linear planning of the general development of the watershed.