黄土高原切沟空间分布特征

Spatial Distribution of Gullies in the Loess Plateau

在区域尺度研究切沟空间分布特征,对黄土高原切沟防治及黄河中游水土保持工作具有重要意义。研究以系统抽样的方法布设256个小流域抽样单元,基于Google Earth亚米级遥感影像,采用人工目视解译的方法,对黄土高原切沟空间分布特征展开研究,结果表明:(1) 92个抽样单元存在切沟,占抽样单元总数35.94%。黄土高原切沟密度均值为1.47 km/km^(2),以小切沟为主。切沟长度、宽度、距分水岭距离均值分别为43.53 m, 6.30 m, 71.19 m。(2)黄土高原切沟主要分布在400 mm等降雨量线附近,尤其是延安及其以西至固原一带,榆林及其以北至东胜一带,小切沟分布与切沟总体分布基本一致,大切沟分布相对分散,在天水—定西一带最为突出。(3)黄土高原切沟所在坡面目前土地利用类型主要为草地(48.51%)、耕地(29.76%)、林地(17.27%)。研究可为黄土高原侵蚀沟分区治理规划提供理论依据。

The exploration on the spatial distribution of gullies at the regional scale is of great importance to the prevention and control of gullies in the Loess Plateau, as well as the soil and water conservation planning in the middle reaches of the Yellow River. In this paper, based on Google Earth sub-meter remote sensing images, 256 small watershed sampling units were arranged using the systematic sampling method, and the spatial distribution characteristics of gullies in the Loess Plateau were studied adopting the visual interpretation method. The results reveal that:(1) gullies were found in 92 sampling units, accounting for 35.94% of the total number of sampling units;the average density of gullies in the Loess Plateau reaches 1.47 km/km^(2), mainly in small gully;the mean values of the gullies length, width and distance from hill top were 43.53 m, 6.30 m and 71.19 m, respectively;(2) gullies in the Loess Plateau mainly distributed near the 400 mm isohyetal line, especially in Yan′an and its west to Guyuan, Yulin and its north to Dongsheng, the distribution of small gullies was basically consistent with the overall distribution of gullies;meanwhile, the distribution of large gullies was relatively scattered and most of them are prominent in Tianshui and Dingxi;(3) at present, the gullies are located the types of the land use of the slope mainly including grassland(48.51%), cultivated land(29.76%) and forest land(17.27%) in the Loess Plateau. These results can provide a theoretical basis for the zoning treatment planning of gullies erosion in the Loess Plateau.