The report deals with the estimation of geomorphology parameters for small catchments using Geographical Information Systems (GIS). Stream channel morphology is literally the study of stream channel form and structure, but generally it is taken to mean their form and structures regarded as a whole or their collective morphology features. Systematic analysis of morphometry of any drainage basin and its stream system is of great importance in understanding the hydrological behavior of the basin.
Geomorphologists have developed parameters, which describe the topology, structure, planform and relief of stream networks. The important geomorphological parameters, which represent the linear, areal and slope aspects of the catchment are required to be evaluated either from the Survey of India toposheets or from existing maps. Application of Geographic Information Systems (GIS) package provides an efficient and accurate means for valuation of these characteristics.
In this study, geomorphological characteristics of various bridge catchments in the Luni Subzone 1(a) have been determined using GIS. The morphological parameters have been estimated using GIS for five catchments located in the subzone. Geomorphological Instantaneous Unit Hydrograph (GIUH) based approach has been applied for one of the catchments and design flood estimated.
The peak value of unit hydrograph obtained using this approach is comparable with the value given in the Flood Estimation Report of Luni subzone 1(a) prepared by the Central Water Commission.
The study indicates that GIUH and GIS based approaches have potential application for the estimation of design floods particularly for ungauged catchments. The approach has an added advantage over the conventional regional unit hydrograph technique as it derives the time variant unit hydrograph based on the storm characteristics without going through the cumbersome procedure of developing the regional unit hydrograph.
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