Flood inundation simulation in Ajoy River using MIKE-FLOOD: Fid-Bau Portal

Flood inundation simulation in Ajoy River using MIKE-FLOOD

Kadam, Prashant / Sen, Dhrubajyoti

Control and risk management of floods using non-structural measures such as flood forecasting and flood warning, flood hazard mapping and flood risk zoning are quite effective. Of these, preparation of flood hazard maps and flood plain zoning require flood inundation simulation, for which various numerical models are available, for example, one-dimensional (1D), two-dimensional (2D) and 1D-2D-coupled models. In the present paper, the last model was used for hydrodynamic simulation for Ajoy River, in West Bengal, from the Ilambazar road bridge to the confluence of river Ajoy with the river Bhagirathi. The flood inundation simulation for the Ajoy River flood plain was carried out using modelling tool MIKE-FLOOD, which integrates the 1-D MIKE-11 model with the 2-D MIKE-21 model. River network layout, cross sections, boundary conditions and hydrodynamic and simulation parameters were the inputs for 1-D MIKE-11. The MIKE-11 hydrodynamic model was calibrated by using the gauge data at a single station (Nutanhat) and the calibrated setup was validated for the same gauging station. The simulated values for the validation period were having good agreement with observed values. Manning's roughness coefficient, n, was the only calibrating parameter. The bathymetry (Digital Elevation Model in MIKE-compatible format) of the study area for the MIKE-21 hydrodynamic setup was the only important input for 2-D MIKE-21. The MIKE-FLOOD setup consisted of simulation files of both MIKE-11 and MIKE-21, where the river banks in MIKE-11 were connected with MIKE-21 cells with lateral links. The simulation of MIKE-FLOOD was carried out for two monsoon months of year 2000 as the flooding was severe for this year. This simulated flood inundation extent by MIKE-FLOOD is compared with Dartmouth Flood Observatory's flood inundation extent map.