From
Stephanie Griffin
Title
Professional Engineering Services Contract with Walter P Moore and University of Texas at Arlington for the development of a Flood Warning-Forecasting System in Grand Prairie in the amount of $100,000
Presenter
Bill Crolley, Executive Director of Planning, Development and Transportation and Stephanie Griffin, Floodplain Administrator
Recommended Action
Approve
Analysis
The City of Grand Prairie has a rain and stream gauge system consisting of 22 gauges. The system provides real-time rain and stream data. The City’s Stormwater Department, Public Works Streets Department, and Office of Emergency Management use the real-time data to determine locations of flooding and to dispatch crews to blockade these locations during and following storm events. This information is also used in deciding when evacuations are warranted.
The proposed flood warning-forecasting system will use the data collected by the City’s existing rain/stream gauge system to answer the “what if” questions that arise in advance of storm events. “What if it rains __ inches? How high will the creek get?”
The flood warning-forecasting system will be developed in multiple phases with Year 1 being the first phase, including:
• Task 1: Conduct a workshop with emergency management officials, first responders, public works staff and stormwater staff to determine the important aspects of a flood warning system for their activities.
• Task 2: Collect existing rainfall data, stream gauge data, H&H models, radar data, topographic information, historical flood information, GIS information, and other appropriate information to build the system to support the necessary flood warning-forecasting operations.
• Task 3: Develop a flood warning-forecasting system at specific locations with above mentioned data to assist City staff during and following rainfall events by providing timely notifications of locations where life safety is at risk. The engineers will develop correlations between rainfall and inundation levels at the specific locations to determine risk. The correlations will be confirmed with the May 2015 storm data, as well as being calibrated during future storm events. Historical radar information will also be incorporated into the model. The information will be incorporated into a GIS layer showing potential inundation areas.
• Task 6a: Document the assumptions, the development of the system and the procedures for use in a report. Train City staff to use and interpret the real-time information of the flood warning-forecasting system.
Pending the outcome of the Year 1 program, the subsequent year may incorporate additional locations or extend the model to incorporate real-time radar and other modeling tools to provide more detailed information at these same locations. Future program expansion will be brought to City Council for consideration.
Financial Consideration
Funding in the amount of $100,000 is available in the Stormwater Utility Surveys and Studies Operating Account (233010/61405).