Unsteady flow analysis using hydrological and hydraulic models for real-time flood forecasting in the Vamsadhara river basin

Abstract

The river Vamsadhara runs through the states of Andhra Pradesh (AP) and Odisha along a stretch of coastline that is prone to cyclonic storms. Riverine flow, along with cyclonic gales, is a crucial issue for most of India's coastal districts. As a result, a developed flood forecasting model is required to mitigate the danger of flooding to a certain level. For evaluating maximum water depth and inundation of flood plains induced by storms under existing and future land use circumstances, hydrological and hydraulic models are more prominently studied. The current work employs hydrological and hydrodynamic models to simulate a real flood inundation model for unsteady flow conditions. The technique involves the processing of the digital elevation models (DEM) to generate flood hydrographs that serve as boundary conditions for the reaches. In the present analysis, Manning's roughness coefficient is used as a sensitive parameter. Calibration and validation of extreme flood events that occurred in 2006, 2010, and 2013 using observed water levels yielded good results, with model performances of 0.79, 0.68, and 0.84, respectively. The findings of the generated depth, velocity, and flood extent maps are presented. These maps can be used to plan for flood disasters and long-term watershed management. HIGHLIGHTS To develop a calibrated rainfall-runoff model for a large river basin.; Interactions between hydrologic and hydrodynamic models.; Simulations of two-dimensional unsteady flow hydrodynamic model.; The high-risk zones generated by this model may help to plan flood prevention, mitigation, relief, and restoration efforts by related government agencies.;

Keywords

• flood inundation modeling
• hec-hms
• hec-ras
• river vamsadhara
• unsteady flow