Determine a Flood Zone
The Federal Emergency Management Agency (FEMA) reports that flooding is the most common natural disaster. Factors other than precipitation determine the extent and severity of floods. Not all floods occur near bodies of water. Impervious surfaces such as roads and parking lots increase the risk for floods by removing land that could absorb floodwaters. According to Flood Smart, we all live in a potential flood zone. The degree of risk varies. FEMA defines flood zones based on geography, history and land cover. Does this Spark an idea?
Instructions
1. Determine the geographical location of the site in question. Certain areas such as coastal areas are more prone to flooding from storm surges caused by extreme weather events. According to FEMA, these locations are high-risk flood zones.
2. Investigate base flood elevation data. Historical data may be available for certain areas from FEMA or local government agencies. Based on an area's history, the risk and categorization of its flood zone can be derived.
3. Use the National Oceanic and Atmospheric Administration's flood mapping tool to identify areas of risk. The National Oceanic and Atmospheric Administration's National Weather Service maintains a current map of flooding conditions. These data present gauge readings based on real-time observations.
4. Locate nearby rivers and streams. Locations in proximity of these waterways fall into floodplain areas. Ecologically speaking, these areas serve as storage areas for seasonal floodwaters. FEMA classifies these areas as high-risk flood zones.
5. Identify other aquatic environments. Aquatic habitats such as ponds and wetlands often are subject to seasonal, ephemeral flooding. Homes and businesses located in these areas may be high-risk flood zones.
6. Find areas located near flood control structures such as levees. Reliance on manmade flood control structures promotes a false sense of security in local populations. Despite these systems, these areas are still considered part of the flood zone.
7. Map wetlands data. According to the U.S. Environmental Protection Agency, wetlands provide important flood protection by absorbing excess storm waters. One acre of wetlands can absorb up to 1 million gallons of water, reducing an area's risk for severe floods.
8. Survey other land cover types. Land cover data combined with water flow and elevation data identify areas at the greatest risk for floods. Using geographic information systems (GIS), potential impacts can be modeled, allowing for a more detailed analysis of flood zones.
9. Determine areas of low to moderate risk using Flood Insurance Rate Map (FIRM) data. These data identify areas of 100-year and 500-year flood zones. Local conditions such as drainage may mitigate the area's flood risk.
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