Multi-Year Floodplain Mapping Project

Map Needs Assessment

In 2010, the Texas Colorado River Floodplain Coalition (TCRFC) contracted Halff Associates to prepare a Flood Modeling and Mapping Need Assessment (MNA) throughout the TCRFC basin.  During the MNA process, Halff coordinated with the Texas Water Development Board (TWDB) to build a database of prior, current, and planned engineering flood studies.  Information for this database was gathered during several community meetings throughout the TCRFC basin.  The meetings included two annual meetings and three regional meetings.  In all, Halff was able to document over 1,600 stream miles of floodplain mapping needs from its member communities.  This first MNA was completed in early 2011.  The data collected from this study was then used to apply for FEMA funding through the Cooperating Technical Partner (CTP) program.  

The TCRFC coordinated closely with the TWDB to apply for a FEMA CTP grant.  The TWDB is a FEMA CTP, which allows for them to collaborate with FEMA in order to maintain current flood hazard information.  With the guidance of TCRFC and the TWDB, Halff Associates prepared a Multi-Year Floodplain Mapping Update Plan based on information from the TCRFC MNA.  Halff utilized the results of the Multi-Year Floodplain Mapping Plan to develop a Mapping Activity Statement (MAS) as the basis of the CTP grant.  In the MNA, streams were categorized and ranked on an individual stream basis.  To be eligible for FEMA funding, the streams needed to be grouped into large watersheds, called Hydrologic Unit Codes (HUCs).  The MNA and Multi-Year Mapping Plan will be will be updated yearly to continue to seek FEMA assistance with the ultimate goal of preparing floodplain maps throughout the Lower Colorado River basin.