Guidelines on Performing Drainage Impact Analysis Using 1D-2D/2D HEC-RAS Models

Two Dimensional (2D) hydraulic models are powerful tools for floodplain management and evaluating flood risk. Few public agencies in the Houston Metropolitan region have adopted 1D-2D/2D models to manage floodplains in their jurisdiction. It is becoming mandatory for all development projects to use these publicly available models to perform Drainage Impact Analyses and to meet the No Adverse Impact requirements. There are important modeling aspects which should not be overlooked while performing a Drainage Impact Analysis using 1D-2D/2D hydraulic models. 

This presentation will discuss five (5) key modeling aspects put together by the authors based on their experience of performing Drainage Impact Analyses for land development projects using 1D-2D and 2D-only HEC-RAS models. The five (5) key modeling aspects include Terrain Modifications, Model Geometry, Model Stabilization Effort, Interpretation of Results, and Accounting for Conveyance, Detention and Floodplain Fill. Modeling aspects mentioned above play a crucial role in making sure that models have minimal errors and incorporate the best floodplain management practices to successfully perform a Drainage Impact Analysis.

By the end of this presentation, attendees will gain an understanding on how to use 1D-2D/2D RAS for Drainage Impact Analyses.