Emerging Flood Inundation Mapping Technologies

Real-Time Dynamic Flood Inundation Mapping

Real-time dynamic flood inundation maps are created on-the-fly using real-time data gathered during flood events. Targeted modeling applications run flood simulations during the flooding event and produce maps.

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ScienceFIM 

In order to promote ongoing scientific studies in the Flood Inundation Mapping (FIM) Program, the USGS Water Resources Mission Area provides small supplemental grants to ongoing or recently completed FIM projects to explore key questions to move flood inundation mapping science forward. 

The intent of a ScienceFIM grant is not to make a map library or supplement a budget shortfall in an existing project, but to provide a little extra time to fully investigate and share the lessons learned from FIM projects. To that end, you must submit a short document at the end of your project discussing your investigation and results. The FIM Program will publish these documents in a yearly ScienceFIM report and share your experiences with the Flood Science Teams and our partners. This is your chance to do that "Oh, I wish I could have tested X to answer Y during that project" opportunity! 

Any USGS Science Center with a current or recently completed FIM project is eligible. If you have any questions, please contact a Flood Science Team Leader or Marie Peppler, FIM Coordinator.

EcoFIM 

Flooding is a primary driver of riverine ecosystem, particularly floodplain functions like plant succession and diversity; nutrient availability, cycling, and flux; and aquatic and terrestrial animal habitat quantity and quality. USGS water and ecosystem scientists have developed geospatial tools to simulate flood extents and depths on floodplains (the fundamental science behind the FIM program), but these tools were missing an important ecosystem element: distribution of water velocities. Modeling water velocities over a floodplain is critical to understanding nutrient and sediment fluxes as well floodplain landscape features (such as wetlands and oxbow lakes) affect habitat. The EcoFIM pilot project seeks to fill in this gap. 

The objective of the EcoFIM project is to develop USGS Flood Inundation Mapping (FIM) library resources for ecosystem studies. The pilot project will focus on a reach of the Maquoketa River flowing through Green Island, Iowa. The reach contains a U.S. Geological Survey (USGS) streamgage (Maquoketa River near Green Island, IA: station number 05418720. The Green Island study area is a 764 acre Wetlands Reserve Enhancement Program (WREP) easement on a damaged levee district area along the Maquoketa River. The Natural Resources Conservation Service (NRCS) restoration goals for this area include improving floodplain function, reducing future levee district repairs, and improving wildlife habitat along the Mississippi River flyway. 

The EcoFIM pilot documentation assist the NRCS efforts by developing a review of influences of flood inundation on floodplain biodiversity (e.g., vegetation, fish and wildlife), biogeochemistry (e.g., nutrient cycling and flux), and ecosystem services (e.g., recreation, safe drinking water, nature viewing), and providing the types of data need to carry out Eco-FIM projects related to these topics. The EcoFIM project will also help decision makers develop map libraries that can inform No Adverse Impact (NAI) improvements to floodplain areas.

RapidFIM

In addition to the traditional hydrologic, hydraulic and geospatial method of creating a flood-inundation map library, USGS is interested in developing and testing additional methods that can be used to make simpler, faster and less expensive maps. These maps will likely be of lower quality so it is necessary to quantify how they differ from traditional studies. With a suite of methods, communities can make informed choices to create map libraries that meet their operational and budget needs. Several methods are being documented and tested, including: 

• The GIS Flood Tool. Instead of performing traditional modeling, the GIS Flood Tool (GFT) uses a relative DEM whose zero point has been referenced to the lowest point of the stream channel along the specified reach. The area of flood inundation is determined for a user-specified river discharge or stream stage by applying the Manning equation at each grid cell. This calculates how fast flow will go through that cell, and which way the water will flow. The resulting inundation patterns can be enhanced by joining additional geographic information like settlement patterns, transportation networks, and land use/land cover. This method is less detailed and relies on some generalized assumptions, but it produces a quick, basic, single-stage inundation map. Download the GIS Flood Tool here.
   
• Imagery-derived products. Flood extents can be derived from processing aerial or satellite imagery, such as LANDSAT, instead of using more intensive DEM-based methods. These maps can be derived quickly during a flood to inform officials and first-responders. Algorithms are designed to interpret the pixel values of visible spectrum or near IR images and produce a quick outline of flooding. To make this technique successful, improvements need to be made to ensure that water surfaces are clearly separated from other large flat areas, like roofs or parking lots. Additionally, these maps only represent a single snapshot of flood conditions, and since no two floods are alike, care should be taken when using them to plan for future events.
   
• Flood Insurance Study interpolations of water-surface profiles. When FEMA assess an area to determine National Flood Insurance Program zones and rates, they use similar methods as the FIM program to estimate flood risk, except their maps are produced for a range of flood probabilities (for example, areas with 1% chance of flooding) instead of a range of stream stages. Additionally, they don't produce as many maps as a typical flood inundation map library, so the gaps between the equivalent stream stage maps can be quite large. However, it might be possible to use interpolation methods to calculate the between-stage water surface profiles instead of having to use more resource-intensive modeling. The USGS is currently testing the accuracy and cost-effectiveness of potential Flood Insurance Study interpolation methods.

Coastal Inundation

Coastal Inundation modeling brings a new set of challenges to the program, as coastal areas are typically very complex hydrologic and hydraulic systems. Depending on the area of interest, these maps may have to consider sea-level rise or beach erosion. If the coastal area is near a river mouth, the riverine, estuarine, and ocean areas all need to be modeled together. The USGS is partnering with National Oceanographic and Atmospheric Administration (NOAA) coastal programs and forecast offices in this area of on-going study.

 

Critical Infrastructure Analysis

For some communities, the motivation for creating a Flood Map Library is to evaluate the susceptibility of critical infrastructure to flood hazards. While flood map libraries can help identify areas and resources most at risk, it is often important to keep the details and location of priority infrastructure secure. The USGS is exploring pilot projects that are examining how flood risks can be evaluated and mapped while still maintaining the safety and privacy of the data.