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Flood Inundation Mapping Tool

A new flood preparedness tool that will help emergency managers protect lives and property in the flood-prone Sweetwater Creek area was unveiled on August 22, 2012 on the banks of the creek at Legion Park.

Developed by scientists from the United States Geological Survey's Georgia Water Science Center, the interactive web-based tool, called a "flood inundation map," is the first of its kind to be created for a major urban area in the southeastern United States.

The epic September 21, 2009 resulted in 10 deaths and more than $250,000,000 total estimated damages in a 7-day period. Floods impacted more than 20,000 homes and businesses and damaged hundreds of roads and bridges, according to Federal Emergency Management Agency. During this time, Sweetwater Creek experienced the highest flows recorded in more than 108 years of measurement with a recorded 31,500 cubic feet per second – 300 times higher than the creek’s normal flow.

This new online tool will help identify where the potential threat of floodwaters is greatest, enabling emergency personnel from FEMA and state and local agencies to make quick decisions about when and how to evacuate residents. State and local officials will be able to use the interactive tool before the rain falls to better plan flood response and resource recovery and to assess evacuation routes at various flood levels.

Flood inundation maps are based on real-time river gauge readings from the United States Geological Survey’s nationwide stream gage network, which monitors water level and flow of the nation's rivers and streams. Remote sensing lidar data and geographic information system technology are used to portray stream gage readings from the Sweetwater Creek gauge onto an online interactive map. The result is a dynamic webpage where users can zoom in and out on different parts of the community to identify locations that would be affected by flooding at different water levels from I-20 north through Austell.

The flood inundation map for Sweetwater Creek is coupled with HAZUS loss-estimation software developed by the Federal Emergency Management Agency and adapted for online display by United States Geological Survey. Using the projected depth and extent of floodwaters from the United States Geological Survey flood inundation maps, this technology enables estimates to be calculated for the potential physical, economic, and social impacts of flooding in a specific area. Flood loss calculations are available through the USGS FIM Program Mapper.

People wishing to access the Sweetwater Creek flood inundation map can find it online. In addition to the map, a webcam along the creek near Legion Park to capture live streaming video, enabling citizens to monitor the creek’s water levels in real time, is available to the public.

WaterAlert and StreaMail are two other online resources that provide residents with timely information about river conditions at important locations. Subscribers have a number of options to choose from on how to get the information. With these tools, emergency managers, resource managers and the public can stay informed and help save lives and reduce property damages by keeping up to date of local river conditions.

Related Links and Documents:

Sweetwater Creek Stream Gauge

Sweetwater Creek Flood Inundation Mapping Tool