Application of 2D numerical simulation for rating curve development and inundation area mapping: a case study of monsoon dominated Dwarkeswar river

Abstract

ABSTRACT While the implementation of real-time flood prediction and warning systems based on real-time continuous rainfall and streamflow data collection has been implemented in a number of river basins in a number of countries such systems require a reliable network of telemetered rainfall and streamflow gauges within the river basin. Typical of a developing country, the southern part of West Bengal has very few gauging stations with, most stations recording only gauge height data. There is a significant lack of local-level information on rating curves and inundation mapping which can be used for flood management purposes and to identify under what conditions areas of the floodplain need to be evacuated to protect human life. Under these circumstances, stand-alone flood modelling can be undertaken to generate rating curves at key locations and inundation maps which can be used during floods to assist emergency managers implement management actions and to decide when to evacuate communities at risk from rising floodwaters. In this study, the monsoon dominated Dwarkeswar River near Arambag Town, Hooghly District, West Bengal was selected for the prediction of a rating curve and inundation area. The August 2016 flood was simulated using a HEC-RAS (Version 5.0.7) rain-on-grid model. The simulated rating curve and inundation area were validated against the river stage data and flooded area observed in the same year. It was concluded that the model was able to simulate the rating curve and inundation area with an acceptable level of accuracy and that this demonstrated the feasibility of applying this approach to other river basins with a limited number of gauges in order to improve flood management and evacuation practices.