While there are estimating design discharge, we are in trouble with how to separate area. Because discharges will be different depending on the shape of area even though there are same size of area. This study is for a reasonable presentation of design discharge method where there are changing characteristics of area with SCS and Clark theory by using HEC-l Model While we were Estimating design discharge with separating area in a relation to Time 01 Concentration(T_c) with SCS , Clark method, we found that if there are no variation of T_e. the value of a discharge is not changed where shapes of area are different though. And from the result of analysis with SCS and Clark method, we ascertained that discharge by the SCS method was more bigger than that of the Clark where Area is less than 100ha. On the other hand, Clark method is more bigger in the more 1000ha