The U.S. Department of Homeland Security, National Protection and Programs Directorate, Office of Cyber and Infrastructure Analysis (OCIA) provided an overview of the National Oceanic and Atmospheric Administration (NOAA) 2016 Spring Flooding Outlook and examines the potential impacts to U.S. critical infrastructure. This product is an update to the April 21, 2015, OCIA Spring Flooding and Critical Infrastructure Note. This update supports DHS leadership; the DHS Protective Security Advisors; and other federal, state, and local agencies. It was developed in coordination with the DHS/National Protection and Programs Directorate/Office of Infrastructure Protection/Sector Outreach and Programs Division, DHS/Federal Emergency Management Agency, NOAA, and the U.S. Army Corps of Engineers. OCIA will continue to monitor conditions and produce additional analysis if significant flooding occurs.
- Spring flooding occurs annually in many regions in the United States. Analysis of flood risk and water supply integrates late summer and fall precipitation, frost depth, soil saturation levels, stream flow levels, snowpack, temperatures, and rate of snowmelt. NOAA predicts snowmelt will not be a significant contributor to spring flooding this year. Seasonal rain and thunderstorms will be the primary factors that could lead to flooding.
- Parts of Arkansas, Louisiana, and eastern Texas have an elevated risk of moderate flooding, as well as communities along the Mississippi River and Missouri River basins and the southeastern United States from Alabama to North Carolina. The Ohio Valley, Tennessee and Cumberland Valleys, Humboldt Valley, Nevada, and Northern Maine are at risk of exceeding minor flooding this spring.
- OCIA assesses that the critical infrastructure Sectors most likely to be degraded or disrupted during a flood event are Transportation Systems, Energy, Dams, Water and Wastewater Systems, Food and Agriculture, and Chemical. The degradation or disruption of these assets, nodes, and systems can have significant cascading effects on many other critical infrastructure sectors.
- Dams and levees may experience added strain or overtopping. Failure or loss of a dam or levee can affect the overall consequences of a flood depending on the extent of failure and the inundation area.
- OCIA recommends that after water subsides from a flooding event, restoration should focus on lifeline sectors. Priorities for restoration should be the following: Water and Wastewater Systems, Healthcare and Public Health, Energy, and Communications Sectors, and the Electricity and Oil and Natural Gas Subsectors.
2016 Spring Flood Outlook
According to NOAA’s U.S. Spring Outlook, areas of the country still under water from torrential rainfall have an elevated risk of moderate flooding through the rest of the season. Analysis of flood risk and water supply integrates late summer and fall precipitation, frost depth, soil saturation levels, stream flow levels, snowpack, temperatures, and rate of snowmelt. Although no widespread areas are at risk of exceeding major flooding, springtime heavy rains in areas with saturated soils may cause localized flooding. Without significant snowpack across most of the country, the flood risk depends highly on the amount of future rainfall in areas with above normal soil moisture and streamflow.
Parts of Arkansas, Louisiana, and eastern Texas have an elevated risk of exceeding moderate flooding, along with communities along the Mississippi River and Missouri River basins and the southeastern United States from Alabama to North Carolina. A chance of moderate flooding exists for the middle Mississippi River because of high soil moisture and streamflows throughout much of the region.
The lower Missouri River basin in Missouri and eastern Kansas has a threat of exceeding moderate flooding through spring. This flood potential will be driven by individual rainstorms typical in the spring, since average to below-average mountain snowpack is unlikely to cause significant flooding from snowmelt.
Eastern Texas has received record amounts of rain, and any additional precipitation along the Sabine, Neches, Trinity, and Navasota Rivers will likely exacerbate flooding. Moderate flooding is possible in the Southeast, including Alabama, Georgia, northern Florida, South Carolina, and North Carolina. This flood potential is driven by individual rainstorms typical in the spring affecting basinsSource: NOAA
where near to above-average soil moisture conditions exist. Based on individual convective rainstorms, the Ohio, Tennessee, and Cumberland Valleys are at risk of exceeding minor flooding.
Because of snowmelt driven flooding, northern Maine and portions of the Humboldt Valley, Nevada, are at risk of exceeding minor flooding. The flood potential from snowmelt and ice jams throughout Alaska this spring is rated as normal. Heavy rainfall at any time can lead to flooding, even in areas where overall risk is considered low.