Understanding Suitability of MIKE 21 and HEC-RAS for 2D Floodplain Modeling

Abstract

Urbanization leads to increase in impervious area and eventually increasing vulnerability to urban flooding. Deer Creek in the city of Brentwood, Missouri, has been experiencing major significant high flows in the past and has flooded the neighboring communities several times. A major step in mitigating the flood is to evaluate the flooding extent. The current research utilizes the Hydrologic Engineering Center River Analysis System (HEC-RAS) and hydrodynamic modelling software-MIKE 21 to study the extent of floodplain in the urbanized area. A comparative study between the models to evaluate the modelling advantages of each model is performed. Moreover, the study focuses on two-dimensional (2D) modelling capabilities of each model as 2D models are more useful in urban areas with more numbers of discrete features. The tradeoff between the accuracy and resources is evaluated while comparing the 2D floodplain modelling capabilities of each models. Channel morphology and flow characteristics for different return period will be incorporated while modeling and the USGS gage data will be utilized for calibration of the models. The models will be calibrated for peak stages along the Deer Creek, with downstream boundary condition of normal depth and the unsteady flow simulations will be performed using the relevant flow hydrographs. The streamflow properties simulated will be derived from the measurements of USGS gaging site near Brentwood, MO.