Treffer: Application of two-dimensional hydraulic modeling in riverine systems using HEC-RAS

Flood simulation models have a wide variety of approaches that are available to compute the water surface elevations associated with a flood event. Some of these models use a One-dimensional (1D) approach, others use a Two-dimensional (2D), and there are others allow the use of integrated 1D and 2D simulations. In 2015, the US Army Corps of Engineering Hydrologic Engineering Center (HEC) released HEC-RAS Version 5.0.3 which performs 1D steady and unsteady flow calculation, as well as 2D unsteady flow calculation. 2D modeling is likely to become more common due to HEC-RAS. This paper is the comparison of 1D and 2D models for a water level in the channel and the floodplain inundation. Two treatments of the problem are explored: (1) a 1D model based upon discretization of floodplain units into storage areas; (2) a 2D model for a channel and a floodplain surface. The two models were tested on the Great Miami River and Bear Creek. The models were assessed by comparison with measured inundation extent. Also, the study reviews the academic basis for modeling floodplain flow based on a two-dimensional analysis. The goal of the proposed research effort will be to include the application of 2D unsteady-state models in future releases of the HEC-RAS 2D model.