Modelling of Rainfall and Runoff for Large River Basin, using HEC HMS Software
The hydrological model is a simple presentation of the hydrological system in the watershed. This model aims to describe the response of a watershed to the hydrological processes that occur when given certain inputs. In the preparation of the hydrological model, the focus of the analysis is focused on the process of diversifying rain into flows through the watershed system. One of the hydrological models that can be used to diversify rainfall into streams (both flow events and continuous flow) is HEC-HMS (Center for Hydrological Engineering - Hydrological Modeling Systems, US Army Corps of Engineers). The purpose of this study was to analyze the relationship of rain runoff in the upper Godavari watershed using the HEC-HMS 4.2 model. The HEC-1 hydrologic model was originally developed in 1967 by Leo R. Beard and other staff members of the Hydrologic Engineering Center, with the U. S. Army Corps of Engineers, to simulate flood hydrographs in complex river basins (Singh 1982). Since then, the program has undergone a revision: different versions of the model with greatly expanded capabilities have been released. The HEC model is designed to simulate the surface runoff response of a catchment to precipitation by representing the catchment with interconnected hydrologic and hydraulic components. It is primarily applicable to flood simulations. In HEC-HMS, the basin model comprises three vital processes; the loss, the transform and the base flow. Each element in the model performs different functions of the precipitation-runoff process within a portion of the catchment or basin known as a sub-basin. An In recent times, GIS (geographic information systems) has become an integral part ofn hydrologic studies because of the spatial character of the parameters and precipitation controlling hydrologic processes. GIS plays a major role in distributed hydrologic model parameterization. This is to overcome gross simplifications made through representation by lumping of parameters at the river basin scale. The extraction of hydrologic information, such as flow direction, flow accumulation, watershed boundaries, and stream networks, from a DEM (digital elevation model) is accomplished through GIS applications. This study combined GIS with HEC-HMS, and analyzed the model’s suitability for the studied catchments.
Keywords - HEC-HMS, Hydrological Modelling.