数字高程模型(DEM)是当前用于流域地形分析的主要数据,由DEM可以提取河网,为不同尺度的水文模型计算和存储地形参数。对黄河小浪底—花园口区间,面积范围为100～1×10⁴km²的8个研究流域,应用网格大小分别为100～1000m6种水平分辨率的栅格DEM进行了流域特征参数的提取和分析。研究表明,DEM的水平分辨率对提取河网的精确性有影响,网格的增大增加了平地处流向确定的随意性。提取的流域面积、长度等有关的参数差别不大,但坡度值变化明显。参数的差别导致主要受长度和坡度因素影响的流域的汇流时间和滞时有较大的不同。

The use of digital elevation models(DEMs)has made it possible to extract drainage network,calculate and store geomorphic parameters for hydrological modeling at different scales.Raster DEMs are the main data source used in hydrology.The effects of different grid cell sizes of raster DEMs on drainage basin characteristics were evaluated.Eight basins ranging approximately from10² km² to10⁴km² with elevations from129m to2618m in Xiaolangdi and Huayuankou section at the middle reaches of the Yellow River basin were examined in this study.Using DEMs with6different horizontal resolutions with grid cell sizes varying from100m to1000m,basin parameters included those commonly used in hydrology and geomorphology such as area,elevation,slope,channel length,drainage network are extracted and derived.According to the result,grid size affects the accuracy of derived drainage network,especially the case in the flat areas.Slope is more sensitive to the resolution of DEM than the area,the length and the shape is.Because of the different parameters derived from DEMs of different resolutions,the concentration time and lag time thus calculated vary more apparently in the same basin.