关键词: 基本地块, 分布式模型, 黄土高原丘陵沟壑区

Abstract:

Distributed erosion model is one of the effective methods to evaluate soil loss. The land patch is a key componentin establishing adistributed erosion model. Now many researchers prefer rectangle as cellsin the model. However, they had not made an agreement about the cell size. Furthermore, when the rectanglecells are employed, it is somehow difficult to keep a balance between the precision and the load of the model, because both of them are decided from the size of the cell. The larger the cellis, the more laboriousthe work is, but it is not always the case that the model will be more precise. Actually, thecellsize should be determined according tothe uniformity of the land in the region where the model is to be applied and the accuracy of the model needed. However, there is a chance that the user of the model, and even the designer of the model, have no actual image of the region, and then have no idea about what size the cell should be. Similarly, when a cell is chosen, the accuracy is not clearly presented. Zhifanggou catchment is a typical area of the hilly loess region in the Loess Plateau. Supported by GIS and SPSS, the authors got the patches of the catchment which haveuniform characters respectively, and analyzedthe statistic result of the patches' areas. It was indicated that the areas rangedfrom less than 1 m 2to almost 200,000 m 2. On the other hand, nearly 67% of the patches congregate into two groups: either below 500 m 2or between 1,000 m 2to 5,000 m 2. Accordingto the results, one can get anapproximate image of the hilly loess region and then be more reasonable to establish or usea distributed erosion model forthat region.

Key words: land patch, distributed erosion model, hillyloess region in the Loess Plateau