A Geomorphological based rainfallrunoff model for ungauged watersheds

Dynamic parameter velocity is an important parameter in GIUH based models. Accuracy of the IUH/UH predicted using GIUH models largely depends on the estimate used for dynamic parameter velocity. Kirpich formula and velocity relationships are independently used to estimate time of concentration for a watershed. In the present study it is shown that combining these empirical formulae a new relationship useful for estimating dynamic parameter velocity for a watershed can be developed. The new technique can be used with easily measurable watershed parameters to estimate dynamic parameter velocity. The model is applied to an ungauged watershed in Barak basin, in India. Applicability of the present model is tested by using a standard UH example reported earlier by different investigators. Peak discharge and time to peak value for the selected example are estimated applying the present technique and are compared with earlier results. Model performances show that the present technique can provide accurate estimate for the dynamic parameter velocity and when used with GIUH approach results to improved prediction for the peak value. The present technique is simple and gives estimate of dynamic parameter velocity on the basis of easily measurable watershed parameters and is useful for ungauged watersheds.