drainage network短语¹⁴⁴⁹⁷²⁺² 基本例句 河网,排水网 How to process depression and flat areas and their drainage direction is a key issue and must be solved prior to the extraction of drainage network based on the digital elevation model DEM. 在利用数字高程模型 DEM模拟坡面流提取流域水系特征过程中，对洼地和平地的处理是首先需要解决的关键问题。 cnki