The CN-SCS method is one of the most common methods in runoff and peak discharge estimation.

Sensitivity analysis and relative importance assessment of five parameters, CN, time of concentration, rainfall

in different return periods, watershed area and

has not completely processed by sensitivity analysis. For finding the nature of curve number SCS method

in estimating peak discharge and its reaction to change in input parameters, the effects of 5 parameters

including CN, time of concentration (TC), watershed area (A), rainfall amount in different return periods

(P) and finally,

equal to 0.133) were surveyed on peak discharge. Results indicate the effective role of CN on peak discharge

as the most important output of model. The sensitivity of the model in estimation of peak discharge

highly increases in large return periods. The sensitivity analysis of curve number SCS method was performed

in MATLAB programming environment.