This research found the better runoff coefficients from the method of GIS by using ARC/INFO soft-ware package to file the surface coverages of the catchments. The runoff quantity were estimated by substituting the found runoff coefficients into the rational formula. The results from this research and those from the traditional rational method, the rational method modified by the kinematic wave theory, the moment method of the instantaneous unit hyd-rograph were all compared with the observed quantity. The compared results shows that the GIS method has simpler theory and more accurate results. Therefore, the GIS method can be used as a reference to estimate the runoff quantity for the futural citified drainage planning.
