数字高程模型（ Digital Elevation Model ， DEM ）能表达地形形态的起伏变化，从中提取的地形参数，可为径流预报提供一定的基础数据。但 DEM 数据是按照一定的分辨率对地表进行近似描述的，多种分辨率 DEM 数据的存在导致了尺度问题的产生。通过提取三峡库区内虾子岭小流域不同分辨率 DEM 的地形参数，分析了不同分辨率 DEM 对坡度和汇流网络精度的影响。研究结果表明：DEM 分辨率对坡度和汇流网络有较大影响，坡度和汇流网络的准确性和 DEM 的空间分辨率密切相关；1m DEM 能够准确反映当地的地形，从中提取的坡度与汇流网络接近于实际值，从 5m DEM 提取的坡度和汇流网络也能较为准确地反映实际值，而10m DEM 、25m DEM和 50m DEM 则不能准确地反映坡度和汇流网络。因此，在进行较为精确的径流预报时，建议采用至少 5m DEM 。在进行粗略估计或较大尺度的径流预报时，可采用 10m DEM 、 25m DEM 和 50m DEM 。

 Digital elevation model (DEM) can represent the local relief. Topographic parameters from DEMs are the basic input data for the runoff prediction. However, different resolutions of DEMs can be used to represent the local terrain approximately. Different resolutions of DEMs lead to generate multiple scale problems. This paper extracts the topographic parameters from different resolutions of DEMs in Xiaziling small watershed and analyses the effects of DEM resolution on the accuracy of slope and discharge network. The results are listed as follows: (1) The accuracy of slope and discharge network depends on the DEMs resolution. (2) 1-m DEM can represent the local terrain, and then the slope and discharge network obtained from it are very close to the real values. The both parameters obtained from 5  m DEM are relatively close to the real values. However, the other resolutions in DEMs can not reflect the real value. Thus, when the runoff prediction is reguired more accurately, the paper suggests that 1-m and 5-m DEMs could be used as the data source. When making a rough estimate or larger  scale runoff predicition, 10-m,25-m and 50-m DEMs can be used.