模拟流域地貌发育过程的空间数据获取与分析

Analysis of Spatial Data for Simulating the Development Process of Topographic Feature of Watershed

运用数字摄影测量与GIS技术对人工模拟降雨条件下小流域模型地貌发育过程进行了动态监测研究,获得了小流域模型不同发育阶段地貌形态高精度、高分辨率的DEM数据、等高线、纵横剖面等数据,计算出了流域模型各种地貌形态参数,并利用GIS技术进行流域发育过程的空间形态进行了可视化和空间分析。研究表明,数字摄影测量与GIS技术可准确快速获取流域地貌形态的相关参数及小流域土壤侵蚀的空间定量分布,对于黄土高原小流域降雨侵蚀产沙过程与地貌形态特征定量作用关系研究及小流域土壤侵蚀预报模型建立具有重要科学意义。

The topographic feature is one of the main factors that influence the process of soil erosion and sediment yield of small watershed. It is very necessary to quantitate the topographic feature of small watershed and get the correlative parameters rapidly. According to the process resemble principle and statistic analysis of the topographic feature of small watershed on the Loess Plateau, the small watershed model is designed as 9.1 m long (max), 5.8 m wide (max), 3.15 m high (max) and the soil density is controlled as 1.39 g/cm^3 . Based on 25 artificial simulated rainfalls, the dynamic development process of the topographic feature of small watershed model is studied by means of photogrammetry and GIS technology. We obtained the data of high precise DEM model, contour line map and the vertical and horizontal section of the small watershed model during different developing periods, including early developing period, active developing period and stable developing period. By GIS technology, the parameters of the topographic feature of the small watershed model are worked out, such as area, length, width, depth, volume and perimeter of the small watershed model. The visualization and spatial analysis of the development process feature of the small watershed model are conducted. The development process of the small watershed model takes on the gully width expansion, the gully bottom cutting down and the gully length increase. The spatial conformation of the main gully and branch gully of the small watershed model are irregular during the early developing and active developing period, and contrary during the stable developing period. The chief reason for the spatial conformation development of the small watershed model is the redistribution of the earth surface substance that is caused by soil erosion, especially the gravity erosion. The research shows that the photogrammetry and GIS technology may be applied to getting the related parameters of the topographic feature and quantitiving spatial distribution of the soil erosion of small watershed quickly and exactly. The technology is very significant to study the quantitive relationship between the soil erosion and sediment yield process and the topographic feature of small watershed on the condition of rainfall on the Loess Plateau. It also provides new method for establishing the soil erosion prediction model of the small watershed in this area.