In the present study, design flood estimation of Morel catchment of Rajasthan state is computed using the Synder approach, regional relationships as proposed by Central Water Commission, Clark's model, Soil Conservation Services (SCS) method and Geomorphological Instantaneous Unit Hydrograph (GIUH) based approach.
The computation of flood hydrographs has been one of the major concerns in the field of water resources engineering. Deterministic approaches have advantages over statistical and empirical approaches as they provide complete shape of the hydrograph.
Mathematical modeling is often resorted to for the purpose of rainfall-runoff process simulation. Continued research in this field has resulted in numerous types of rainfall-runoff models. Conceptual models and physically based models are widely used for simulation and design flood evaluation. The linearity principle of unit hydrograph theory has been widely applied for the simulation of rainfall-runoff process, particularly for small and medium sized catchments.
The unit hydrographs can be derived by analyzing the historical rainfall-runoff records for the gauged catchments. However, for ungauged catchments some indirect approaches have been used for the derivation of the unit hydrographs. Due to scarcity of data, particularly for small and medium sized-catchments, physically based models are very difficult to implement.
For these catchments, emphasis is either on using the regional information or the geomorphological characteristics of the basin for estimation of floods. GIUH is an approach available for the simulation of flood events, especially for the ungauged catchments.
In this study, to estimate the parameters of Clark model, relationship between time of concentration & catchment area and time of concentration & ratio of length of stream channel to the equivalent slope have been developed for the region. The ratio of storage coefficient to the sum of time of concentration and storage coefficient is worked out for each catchment of the region and based on the median value of this ratio, a value is assigned to the region. The design flood for the basin is computed based on Clark model and GIUH approach as they are more appropriate for the ungauged catchments.
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