Hydrodynamic Simulation of River Ambica for Riverbed Assessment: A Case Study of Navsari Region

Abstract

Physically based hydraulic or hydrological model will simulate the dynamics flow water of a river network against space and time with varying reach boundary conditions that may be enforced for the case of Ambica river stream. Such stream models refers to the physically based hydrologic or hydraulic models which usually helps in crucial part of flood prediction, flood forecasting and fluctuation of tidal that forecasts river levels in flood prone areas off the center stream of Ambica river. For the setting of a any river model, the measurements of river geometry, bed depth/slope, floodplain mapping and boundary condition flow are essential. The discharge and water level in the river reach of Ambika are controlled by Jhuj and Kelia dam which is 68.9 and 57.6 km away from Navsari city, respectively. Major flood events occurred in the years 1981, 1994, 1997, 2001, 2003, 2004, 2005, 2006, 2007, 2013 and 2014. Therefore, it becomes highly necessary that flood events are studied and analysed properly in order to propose adequate flood control and protection measures in time to come. At present, the carrying capacity of Ambica River is approximately around 2.5 lakhs cusecs (7079 m³/s). In this paper, we used one-dimensional model which is released by US Army Corps of Engineers, i.e. HEC-RAS 5.0.4. over the river reach of Ambica, Navsari. In this paper, hydrodynamic simulation is performed to compute the water surface profiles for five-peak flood discharge of year 1981, 1994, 1997, 2004 and 2006. Thus, in this present paper from Ichhapore to Salej village which is approximately 1170 m long is selected for study purpose. The computed sections are then compared with existing sections on the river reach and are checked whether the sections are critical or not. Based on above study, it is recommended that the cross sections which the water is overtopped on the existing section, levees or retaining is to be constructed or need to be raised.