Dongfenghu Lake Gorge: when the surface water flows, in order to gain maximum hydraulic gradient, it searches for the best way to reduce its potential energy to the minimum by discharging to a lower erosion basis. This process results that the surface river erodes and cuts downward vertically continuously until it reachs basically the same level as erosion basis. During its supplement, runoff and discharge processes, karst gorge with the height being over its width in terms of size is formed gradually.We call this as top-down formulation and evolution mode of the gorge.

 
Schematic diagram for evolution modes of top-down gorge formation