Impact of Size and Location of Wetlands on Watershed-Scale Flood Control

This paper presents a case study on the impact of the size and location of wetlands on watershed-scale flood control utilizing the Cypress Creek Watershed in Houston, Texas as the study area. Wetlands of different sizes were implemented at different locations (upstream, midstream, and downstream) of the watershed and corresponding hydrologic and hydraulic simulations were performed to investigate the impact that wetland size and location parameters have on downstream flood conditions. This study used HEC-HMS as the hydrologic model for the watershed, and HEC-RAS as the hydraulic model for rivers within the watershed. Wetlands were implemented in the HEC-HMS model as reservoirs. Simulation results indicate the more upstream wetlands are located within the watershed, the smaller the flood area, the shallower the flood depth, and the shorter the flood duration at the downstream region of the watershed. In addition, the downstream flood area, flood depth, and flood duration decrease as the size (storage capacity) of wetlands increases.