Synthetic Unit Hydrograph for Un-gauged Basins using Geomorphologic Instantaneous Unit Hydrograph (GIUH) based Nash model

Abstract

The present study examines one of the most widely used flood hydrograph modelling approach for gauged and un-gauged basins and efforts have been made to produce Synthetic Unit Hydrograph (SUH) with the help of Nash Model, which has a low relative error and based on the Geomorphological Instantaneous Unit Hydrograph (GIUH). Under the suggested methodology forty one tributaries of Narmada basin were selected from the state of Madhya Pradesh and Gujarat for study purpose. Arc-GIS 10.2.2 software was used for analysis purpose. SRTM Image popularly known as Digital Elevation Model (DEM) was used as an input.  Various Geomorphological characteristics of the streams as output were derived from Arc GIS software: Stream Order, Total number of streams of different order, Stream Length, Area of the catchment, Slope of the area, etc. The complete data was derived through Arc-GIS 10.2.2 software and various parameters were extracted. From the Geomorphological parameter obtained, the Nash parameters were derived and synthetic Unit Hydrograph was produced and was found smooth and time saving. The result shows that Bifurcation Ratio=4.17779, Stream Length Ratio=2.890911, Stream Area Ratio=2.55258, Main stream Length (km) =56.66, average slope (S) = 0.077068 (m/m) = 7.7 %, Dynamic velocity (m/s) = 3.956173766, Nash parameter (n) =5.2412, Nash parameter (K in hr.) = 1.30188, Peak Time (t_P) = 5.521533456 hr, Peak Discharge (q_P) = 335.1370794 cumec.