RESILIENCECompound-Flood Modeling Tools Hel Build Community Climate Resilience

Published 6 January 2022

In 2021, extreme flooding from rain affected residents across the United States, causing property damage and loss of life. These extreme weather events are becoming all too common. In fact, a recent United Nations report—Climate Change 2021—found that heavy rain events are likely to become more intense and frequent, resulting in an increase in severe flooding events around the globe.

When Hurricane Ida made landfall in Louisiana in August 2021, it was classified as a Category 4 storm with 150 mph winds, a storm surge that measured at more than five feet in New Orleans and 10 feet in Grand Isle, and rainfall of more than 15 inches. Inland flooding from the rain, combined with overflowing waterways and storm-surge flooding, resulted in a compound-flood event.

In 2021, extreme flooding from rain affected residents across the United States, causing property damage and loss of life. These extreme weather events are becoming all too common. In fact, a recent United Nations report—Climate Change 2021—found that heavy rain events are likely to become more intense and frequent, resulting in an increase in severe flooding events around the globe.

Preparing for and responding to climate change is a priority for the Department of Homeland Security (DHS), with Secretary Alejandro Mayorkas announcing earlier this year the creation of a Climate Change Action Group to drive the department’s cross-functional efforts. And as DHS’ research and development arm, the Science and Technology Directorate (S&T) is developing resilience tools and resources to help communities and first responders prepare for the effects of climate change.

Community-Oriented Flood Risk Planning in Coastal Communities
South Carolina has had its share of historic weather events that caused severe flooding. In October 2016, Hurricane Matthew was a Category 1 storm when it reached the state and left overwhelming flooding in its wake from storm surge, heavy rainfall, and overflowing rivers. In September 2017, Hurricane Irma, one of the strongest hurricanes recorded in the Atlantic Ocean, caused extensive destruction in the Caribbean and southeastern U.S. Irma made landfall in Florida as a Category 3 storm, and while it had weakened into a tropical storm when it moved onto Georgia and South Carolina, it brought significant storm-surge flooding and wind gusts, tornadoes, flooding rainfall, and river flooding. When an area is overcome by multiple sources of flooding at once, it becomes a compound-flood event.