City of San Marcos
The Texas Water Development Board (TWDB) provides assistance to local communities through the Flood Protection Planning Program, aimed at helping local communities study flood-troubled watersheds on a comprehensive basis. Espey Consultants, Inc. prepared a successful grant application for the City of San Marcos, bringing $200,000 of state assistance to match the City’s $200,000 contribution and $33,000 of in-kind services from the City and its participating partners: Hays County, GBRA, EAA and the Upper San Marcos Watershed Management District. The project covers the analysis of 7 major watersheds in the city, and aims to identify problem areas, develop and model both structural and non-structural solutions, conduct a cost-benefit analysis of viable flood protection measures, and finally produce a plan to guide the City in implementing the Flood Protection Plan.
EC is developing a series of georeferenced hydrologic and hydraulic models for seven major watersheds that cover San Marcos, its ETJ and portions of Hays County. Given the unique characteristics of these watersheds in “Flash Flood Alley”, the most recently available topographic and land use data were utilized to produce the most accurate rainfall runoff model. Field survey at over 25 structural crossings was taken and is carefully integrated into WISE software to delineate floodplain boundaries.
An analysis of the resulting floodplains, risk to life and property, potential economic damage, and emergency management concerns guide the City and EC in developing flood protection measures that are cost effective and implementable, while addressing the entire needs of the watershed. Additional topics, such as Flood Early Warning Systems along the Blanco River and the potential for dual-purpose flood control and water supply reservoirs can also be evaluated together with the participating partners, such as the GBRA and EAA.