Hybrid model for derivation of synthetic unit hydrograph

Splitting the Nash single linear reservoir into two serially connected reservoirs of unequal storage coefficients (one hybrid unit) for a physically realistic response, a hybrid model is introduced for derivation of a synthetic unit hydrograph. Empirical relations are given for estimation of the two storage coefficients from known peak flow (q(p)) and time to peak (t(p)). The hybrid model with two serially connected units is found to work significantly better than the most widely used methods such as those of Snyder, the Soil Conservation Service (SCS), and the two-parameter gamma distribution when tested on synthetically generated data and the data from four catchments from India and one from Turkey. The workability of the proposed approach was also tested for partial and no data availability situations.