APPLICATION OF A TIME VARIANT CONCEPTUAL MODEL TO SMALL CATCHMENTS

Abstract

Unit hydrographapproach is based upon the principles of (i) invariance and (ii) superposition. Those assumptions may not be true. It is often observed that an average (or a representative) unit hydrograph need not necessarily reproduce all the floods in a catch-mont. In this study, hourly gaune data, discharge data and hourly rainfall data available in small catchments (area less than 200 sq.?cm) of Krishna and Pennar basins have been used. Out of ten catchments, the approach has boon developed on eight catchments and the remaining two have been used for testing purposes. Two paramoto:c Hash Model (2,6) was used to dove—lop Instantaneous Unit Hydrograph(I.U.H.) . Utilising the I.U.H., one hour unit hydrograph was derived and rainfall excess was applied on it to give a computed direct runoff hydrograph. It was observed that the reproduction of flood hydrographs by this method was not satisfactory.