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Lack of Flood Maps at Many U.S. Military Bases Creates Risks

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An aerial view of Offutt Air Force Base affected by major flood waters March 17, 2019. An increase in water levels of surrounding rivers and waterways caused by record-setting snowfall over the winter in addition to a large drop in air pressure caused widespread flooding across the state of Nebraska. (U.S. Air Force photo by TSgt. Rachelle Blake)

By Dr. Marc Kodack

The 2019 National Defense Authorization Act (NDAA) required that for any proposed major or minor U.S. military construction project within the Department of Defense (DoD), the Pentagon must disclose to Congress whether or not that project is located within the 100-year floodplain. DoD was to use the most recent Federal Emergency Management Agency (FEMA) flood hazard data. If the FEMA data were unavailable, DoD was directed to create a process to determine the 100-year floodplain through risk analysis that conforms to standards used in federal flood risk assessments (see here). Elsewhere in the same NDAA, Congress required that climate resiliency be included in master plans for major military installations, although it did not define “major military installation.” Resiliency includes the ability of an installation to “avoid, prepare for, minimize the effect of, adapt to, and recover from extreme weather events…(Section 2805).”

In the 2020 NDAA, Congress further required that DoD include in its’ installation master plans a discussion of risks and threats that included those from extreme weather and flooding. It also said that master plans should deliberately consider how assets and infrastructure associated with critical missions are vulnerable to these risks and threats (Section 2801). However, for installation master planners to accurately determine the boundaries of existing floodplains and how these floodplains may change under climate change, they must be able to access accurate flood hazard maps, such as those in FEMA’s national flood map program.

The Association of Floodplain Managers (2020) recently reviewed the National Flood Insurance Program and the National Flood Mapping Program. They concluded that the flood mapping program requires significant additional funding to bring many flood hazard maps throughout the U.S. up-to-date. In addition, annual maintenance funding is also currently inadequate. If installation master planners use out-of-date flood maps, they cannot accurately determine installation resilience as-a-whole or for individual assets and infrastructure used in critical missions that will be affected by extreme weather, flooding, and climate change. They will fail to reduce climate risk.

For all the types of natural disasters that occur in the U.S., floods are the most damaging resulting in $155 billion in direct losses since 2010. Average annual direct losses from floods have been increasing since 1990 with an average loss of $17 billion between 2010-2018. Indirect costs include “lost wages, agricultural losses for crops and livestock, expenses for evacuating, risk for first responders and significant physical and mental health issues following the event…” Transportation systems are also affected which disrupt supply chains for food and fuel. Development and climate change are the two primary variables that will affect future flooding. Development will increase impervious surfaces leading to greater run-off, whereas climate change will cause more frequent coastal flooding through sea-level rise and increases in extreme rainfall across the U.S. As an example of how floods can affect a military installation, in 2019 floods caused over $1 billion in damages to infrastructure at Offutt Air Force Base, Nebraska. It will take five years before the base fully recovers. This assumes that no future flooding events occur over the next five years. Fortunately, spring 2020 flooding along the Missouri River and its tributaries around Offutt is not anticipated.

The Federal Emergency Management Agency (FEMA) has the responsibility for the National Flood Mapping Program (NFIP). FEMA has the responsibility to ensure that the flood maps can be used to make flood risk determinations. For example, state and local governments can use the maps to determine flood risk related to development within their jurisdiction. FEMA also needs to ensure that the NFIP maps are regularly reviewed and updated to include climate change forecasts and its effects on existing floodplains. Data from other sources, such as that from the National Oceanic and Atmospheric Administration (see here), the U.S. Army Corps of Engineers, and the U.S. Geological Survey (USGS, elevation data), needs to reviewed to determine if these data change local flood hazards. However, there is “no consistent, definitive timetable for revising and updating” flood maps in any community (see also here).

Approximately one-third of the existing stream miles in the U.S. have flood maps. Not quite 50% of shorelines have flood maps. FEMA has prioritized floodplain mapping in those areas with the largest populations and most flood insurance policies assuming these areas are at the highest risk areas for flooding. The majority of unmapped areas are in the western U.S. where 50-100% of the counties are unmapped. Some of these maps are still on paper and are 30 years old. By law, FEMA is supposed to review flood maps every five years and determine if the maps need to be updated or changed. To address all the multiple issues in the national flood mapping program, funding needs are estimated at $11.7 billion with a $480 million required for annual maintenance. The backlog and large cost to reduce this backlog mean that many communities will not have the data they need to reduce their flooding risk even if they have a planning process in place that addresses emergency responses to natural disasters whatever their cause.

Installation master planners should be using multiple tools to determine if their installation might be vulnerable to flooding. One tool, FEMA flood maps, may or may not be available. For those installations located in the western U.S., these maps do not exist or are significantly out of date. Thus, installation master planners will have to find other sources of flood data/maps, e.g., USGS, to assess their flood risk as part of their planned development decisions. These decisions will affect infrastructure associated with critical missions currently located on an installation or that could be created/transferred to that installation under future base realignment and closure actions.

Dr. Marc Kodack is Senior Fellow at the Center for Climate and Security and former Sustainability and Water Program Manager in the Office of the Deputy Assistant Secretary of the Army for Energy and Sustainability.

* This post is part of the Council on Strategic Risks’ “Responsibility to Prepare and Prevent” Blog Series, designed to increase the tempo and scale of relevant and useful analysis during a time of crisis

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