黄土丘陵沟壑区大空间尺度林草植被减沙方程的尺度适应性

黄土丘陵沟壑区大空间尺度植被减沙方程是分析黄土高原植被变化产沙效应的有效工具,其在不同空间尺度的适应性对于黄河水沙情势变化研究十分重要。运用数值试验方法,研究黄土丘陵沟壑区大空间尺度林草植被减沙方程在小流域、子流域和栅格等3种空间尺度的适应性。结果显示,黄土丘陵沟壑区大空间尺度林草植被减沙方程在各空间尺度的总体估算偏差（D）由小到大排序为小流域（D=52.26%）<子流域（D=60.07%）<栅格（D=92.17%）,纳什效率系数（NSE）由大到小排序为小流域（0.21）>子流域（-0.31）>栅格（-0.80）。可见,黄土丘陵沟壑区大空间尺度植被减沙方程在约500 km²以上的流域单元较为适用,在500 km²以下的子流域和栅格单元不适用。该研究成果可为黄土丘陵沟壑区大空间尺度林草植被减沙方程的推广应用提供参考。

Scale Adaptability of the Large-Scale Vegetation Reducing Sediment Equation in the Loess Hilly Region

The large- scale vegetation reducing sediment equation in the loess hilly region (LVRSE) is one of the efficient tools for analyzing the effect of vegetation change on sediment yield in the Loess Plateau, and its adaptability at different spatial scales is very important to study the water and sediment changes of Yellow River. This research uses a numericalexperimental method to study the adaptability of LVRSE at small basin, sub- basin and grid scales. The result shows that the overall estimation bias (D) of LVRSE at different spatial scales ranks in the following order: small basin (D=52.26%), sub-basin (D=60.07%), grid (D= 92.17%); the Nash- Sutcliffe model efficiency coefficient (NSE) of the LVRSE at different spatial scales ranks in the following order: small basin (NSE =0.21), sub-basin (NSE=-0.31), grid (NSE=-0.80). This result indicates that the LVRSE is more applicable to small basins of more than about 500 km2, and not applicable to the sub-basins and grids of less than 500 km2. These findings can provide reference for the popularization and application of the LVRSE.