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.

岩溶斜坡和岩溶洼为表汇集区及排泄区，岩溶作用相对，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.

这样既可以反映出河道附近格网的流方向，又可以让各个子流域内的汇流方向和流方向不会跨越子流域的分岭。