subdrainage

The karst depression belongs to the accumulative area of surface water and subdrainage area of subsurface water, the karstification is relatively week, and reservoirs are undeveloped.

岩溶斜坡和岩溶洼地为地表水汇集区及地下水排泄区，岩溶作用相对较，不发育。

This method can acurately simulate the flow direction in gird near river, and can keep the direction of waterflow from crossing the watershed of subdrainage area.

这样既可以较确地反映出河道附近水流方向，又可以让各个子流域内汇流方向和水流方向不会跨越子流域分水岭。