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，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.

这样既可以较精确地反映出河道附近格网的水，又可以让各个子域内的汇水不会跨越子域的分水岭。