*2.1. Study Area*

A typical karst trough valley (LangXi trough valley) in the southwest karst mountainous region was selected as the research object. LangXi trough valley is located in YinJiang County of Tongren region in northeastern Guizhou Province, and the administrative area covers several townships in the territory, including BanXi town, TaiShui town, LangXi town, Eling town, LuoChang township, BaoXi township, and Tinzhai township, with a total area of 130.34 km2. The geographical position is 108◦24 36.43–108◦34 8.62 E; 27◦53 59.55–28◦6 22.16 N. There are 35 administrative villages in LangXi karst trough valley, including SanCun village, XiBu village, HeXi village, etc. Based on the study's purpose and the area's topographical features, the study area was divided into five trough valley locations: the top of the trough valley, the trough slope, the dam, and the east and west slopes (Figure 1).
