Development of real-time flood forecast model for vamsadhara river through hydrological approach

Hydrologic simulation of large river catchments, and the decision to choose a computerized model, is a complex job that necessitates a thorough knowledge of rainfall-runoff processes. While modeling involves proper estimation of direct surface runoff volume and peak discharge in a watershed. In the present study, a real-time flood forecasting model is developed using Hydrological Modelling System (HMS) to forecast floods and River Analysis System (RAS) to identify inundation areas in the Vamsadhara river basin located between Odisha and Andhra Pradesh in India. The flood prediction model is constructed using a simulation of spatial data. The approach includes a loss model to compute infiltration loss, a transform model to simulate runoff rate, and a Muskingum routing method to route flow in a river along with model calibration, and validation with field data. Topographic and hydrologic parameters for each of 17 sub-basins are computed using Land Use, Land Cover (LULC). Muskingum parameters are also calculated. The hydrological model has been calibrated using the precipitation and gauge discharge data of the 2006 flood event. For validation of the modeling process, flood events in 2010 and 2013 at two Gunupur and Kashinagar gauge stations were chosen. The simulated peak discharges obtained are sufficiently accurate with observed data at both the gauge stations. The Nash-Sutcliffe efficiency (NSE) obtained for the calibration period are 0.78 & 0.77, which shows that model performance is good and accepted for simulation of streamflow. Similarly, the model performance for validation period is 0.81 & 0.80 for 2010 flood event while for the 2013 flood event are 0.84 & 0.82 indicating very good model performance. Overall, the study revealed that the HMS model could be employed for the calculation of surface runoff and flood forecasting in similar areas and conditions existing nearby catchments. Flood inundation maps generated with HEC-GeoRAS and Hydrologic Engineering Center-River Analysis System (HEC-RAS) for 1D steady flow demonstrate the model's output. As a result, this would help in the effective monitoring of flood hazards and the sustainable management of watersheds.