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.

溶斜坡和溶洼地为地表水汇集及地下水排，溶作用相对较，储层不发育。

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.

这以较精确地反映出河道附近格网的水流方向，又以让各个子流域内的汇流方向和水流方向不会跨越子流域的分水岭。