The study attempts to apply Geomorphological Instantaneous Unit Hydrograph (GIUH) and Geographical Information Systems (GIS) based approach for flood estimation. The design storm data of four catchments along with morphological characteristics have been considered. The geomorphological parameters and time area diagrams for each of the dam catchments were generated using the GIS package, Integrated Land and Water Information Systems (ILWIS).
The geomorphological parameters together with the time-area diagram forms an important input for the GIUH based Clark model. This model has been applied for deriving the instantaneous unit hydrograph and thereby to estimate the design flood in four dam catchments located in Luni and Chambal basins in Rajasthan viz. Jawai, Sei, Gamabhiri and Alnia. A review of the previous studies carried out using GIUH approach has been presented. Furthermore, a review of studies carried out using GIS techniques is also provided.
The design flood estimates have been obtained for different scenarios of the design storm. These design flood estimates have been compared with the available design flood estimates in order to examine the applicability of the GIUH approach. Velocity is an important design parameter and its estimation for design conditions is a crucial issue.
Quantitative understanding and prediction of the processes of runoff generation and its transmission to the outlet is one of the most challenging areas of hydrology. Unit hydrograph techniques have been widely applied for the estimation of design flood hydrograph at the site of interest. For ungauged catchments, unit hydrograph may be derived using either regional unit hydrograph approach or alternatively by using the GIUH approach. The GIUH approach maybe applied for simulation of flood events particularly for ungauged catchments.
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