坡沟系统侵蚀时空分布特征试验研究

Experimental Study on Spatial and Temporal Distribution Characteristics of Erosion in the Slope-Gully System

依托水利部黄土高原水土流失过程与控制重点实验室的水土流失试验厅,采取高精度三维激光扫描技术获取坡沟系统不同侵蚀发育阶段的地形Grid数据,借助Arc GIS软件中Arc Toolbox的3D Analyst工具和数据管理工具模块的分析功能,从时间和空间角度分别对坡沟系统侵蚀发育过程进行量化分析。研究表明:1坡面侵蚀和沟坡侵蚀对坡沟系统产沙量贡献率的大小受降雨历时和侵蚀发育阶段影响,降雨初期的面蚀阶段以沟坡侵蚀为主,继而向坡面侵蚀为主转化。在雨强85 mm/h、降雨历时60 min的模拟试验条件下,降雨过程的前20 min面蚀阶段坡面与沟坡侵蚀贡献率之比约为3∶7,降雨过程的后20~60 min的细沟和切沟侵蚀阶段坡面与沟坡侵蚀贡献率之比约为7∶3;2径流含沙量与地表侵蚀空间不同步,试验条件下径流含沙量峰值区约滞后于侵蚀强度较大部位2个断面(2 m)。

Experiments were carried out in the Hall of Soil Erosion which belongs to the Key Laboratory of Soil and Water Loss Process and Control on the Loess Plateau of MWR. This study used the high-precision three-dimensional laser scanning to get the data of terrain develop- mental in slope-gully system and quantified the erosion process by using ArcGIS software from the angle of rainfall periods and spatial distri- bution. The results show that：a） the slope erosion and gully erosion contribution rates of the whole system sediment yield are different for different rainfall duration or terrain developmental stages. At the surface erosion stage, the contribution rate of gully erosion is bigger than that of slope erosion, And then it converts with the development of erosion. Under the experimental conditions of rainfall intensity 85 mm/h and the duration 60 minutes, the sediment contribution ratio of slope erosion and gully erosion is 3 ： 7 at surface erosion stage during the rainfall in 20 minutes,and the ratio is 7 ： 3 in 20-60 minutes of rill and gully erosion processes; b） erosion and high sediment concentration are not syn- chronized in the spatial distribution. The peak value of runoff sediment concentration locates downstream at about 2 m behind the strong erosion zone under the experimental conditions.