Using HEC-RAS 2D Rain-on-Grid for Dam H & H

Abstract Only - The HEC-RAS 2-dimensional (2D) model has become the standard for dam breach analysis over the past few years, but much of the hydrologic routing is still done using traditional rainfall runoff modeling. Implementing 2D rain-on-grid hydrology for the hydrologic routing can save time by reducing the amount of initial work needed for rainfall runoff modeling, reduce the complexity of the modeling by using a single model for the full analysis, reduce the error caused by artificial hydrograph transforms and assumed timing calculations, and show a more complete picture of what is happening in the watershed.
This presentation will show how the HEC-RAS 2D rain-on-grid model can be used to model hydrology and hydraulics using an example that features three dams in series, which can be a complex problem using two different modeling systems. This example shows the shortcomings of the current implementation of 2D in HEC-RAS and how to work around these limitations. It will also compare the results to traditional rainfall runoff modeling completed using HEC-HMS and show the results of a sensitivity analysis of various input parameters.
While the 2D rain-on-grid implementation in HEC-RAS still has some shortcomings, it can still produce more realistic results than traditional modeling in many situations.