沟壑密度调查应采取水文网络法

Discussion on Metheds of Gully Density Investigation

沟壑密度是评价小流域沟蚀程度的指标，具体地反映了小流域沟蚀轮廓。目前，对于沟壑密度调查，尚无统一规定，有方格网法、小斑号法等。这些方法虽能描述小流域沟蚀现状，但不能为沟壑治理的工程设计提供前期资料。水文网络法，从沟道发育入手，将大流域依沟道分布划分为若干小流域，结合工程布局进行调查，计算结果与其它方法相同，结论相同，而基础资料均为以后的工程设计提供了必要的准备。

Gully density is an index to evaluate gully erosion and describe the sketch of gully erosion in a watershed. At present, some different approaches, such as grid approach and small spot number approach etc., are used to investigate the gully density. However, there is no unique approach to be used by different investigators. Although these methods mentioned above can describe the existing condition of the gully erosion in a small watershed, it can not provide the antecedent information for the design of gully harnessing engineering. Nevertheless, the hydrological network approach, which can divide a large watershed into several sub-watersheds according to the gully characteristics, can give the same result of gully density in a watershed as the other approaches by combining investigation of engineering layout. Additionally, the basic data gained by using the hydrological network approach are in preparation for the later design of gully harnessing engineering, which can be used anytime.