UNIT HYDROGRAPH BASED RAINFALL RUNOFF MODELS

Abstract

The unit hydrograph is an important tool for the hydrologists for the flood forecasting and for the design of hydraulic structures. In the present study, approach of the composite unit hydrograph derivation has been used for flood simulation and flood forecasting in two catchments from different climates. Two models have been used herein, viz. the conventional model, in which the total rainfall and the total runoff are considered as the input and the output respectively and the Linear perturbation Model (LPM), in which departures of the rainfall and the runoff from their corresponding mean values are considered as the input and the output respectively. It has been found that the medium sized catchments which are considered in the present study do not show well defined seasonal behaviour, hence the LPM is able to produce marginally better results than the conventional model. However, it has been shown that method of derivation of the composite pulse response results in satisfactory simulation and forecasting of the flood.