NIH/CS/13-14: Flow modelling in Gauthami Godavari river

Abstract

The surface water levels of a river, especially at its river mouth are required for planning and managing flood alleviation schemes and river engineering works. In lower reaches of a river flood plain inundation may occur from a high tide in combination with a high flood. Such studies will help understand the interaction between river flows from upstream and tidal forcing through river mouth. The results from the study are useful for various govt. departments that associate in hydrologic design of flood banks and tidal banks; planning flood plain zoning and disaster preparedness and flood, storm surge vulnerability mapping. In this study, river flow is simulated using SWMM for the network of nodes that correspond to locations where cross-section data exists and links that identify stream portion between two nodes to represent the Gauthami River upto its mouth from just downstream of Dowlaiswaram. Two scenarios, the first one to simulate for the condition of original flood banks that existed and second one for scenario where flood embankment are raised to pass the peak flood studied. The impact of resistance to river flow due to tidal effect and rise in river level at upstream nodes is large and is about 1.5 m above flood water level in the river initially and gradually subsides with time as the tidal effect reduces. The head and depth at two last nodes located representing two outfalls is evaluated. It is observed that the head at Outfall-1 of the northern branch is well connected to the main river network compared to the Outfall-2, as the discharge of the river is peaking up and flows during ebb tide to sea. The complete output of simulation will help draw detailed information on the river flow and river levels.