摘要： ArcGIS采用D8算法计算水流方向（9.3.1后新增），输入数据应首先完成了洼地填充处理：One of the keys to deriving hydrologic characteristics about a surface is the ability to determine the direction of flow from every cell in the raster. This is done with the Flow Direction function.This function takes a surface as input and outputs a ras 阅读全文