Harris County Flood Control District:
Continuous Updates Program

Harris County, TX - The Harris County Flood Control District (HCFCD), a Cooperating Technical Partner (CTP) in association with the Federal Emergency Management Agency (FEMA), recently completed a countywide Flood Insurance Study (FIS) restudy for Harris County, Texas (Houston, Texas). This restudy resulted in the modeling and floodplain delineation of 22 major watersheds and approximately 1,300 miles of channels using HEC-HMS and HEC-RAS. The new floodplain maps became effective on June 18, 2007.

Harris County, Texas is a growing community with a highly active floodplain-related development. Presently there are many Letter of Map Changes (LOMC), consisting of both a Conditional Letter of Map Revisions (CLOMR) and Letter of Map Revisions (LOMR), in the queue at FEMA. These map revisions will be approved in the near future and will change the models and floodplains within Harris County. Furthermore, additional CLOMRs and LOMRs will be submitted to FEMA in the future by local floodplain managers and consultants. With the vast number of LOMRs and CLOMRs, maintaining the models into the future by considering all the map revisions is a considerable challenge. HCFCD has developed a solution to properly manage the models into the future on a continuous basis. This program is called “continuous updates.”

The goal of continuous updates is to manage a master set of current and accurate hydrologic and hydraulic models and their supporting data for watersheds in Harris County. These models are developed and maintained to:

1. Support the Flood Control District’s planning and project development activities,

2. Provide local communities an understanding of flood risk [e.g., FEMA’s National Flood Insurance Program (NFIP)], and

3. Provide the development community with realistic tools to assess and plan development projects.

HCFCD has become engaged in the management of the effective models and associated data; these activities are outlined in Mapping Activity Statement (MAS) No. 14. In order to accomplish the objective outlined above, HCFCD shall be the custodian of the model sets and supporting data. The items in MAS No. 14 are as follows:

1. HCFCD development of Modeling Management Standards to ensure consistent products.

2. HCFCD development of a web-based application to distribute, notify, and check models and supporting data.

3. Continuous updating of the FEMA effective model set by incorporating recently approved LOMRs into the master model set, which then can be distributed to the community through HCFCD's web-based application.