HurricanesHurricanes can cause enormous damage inland, but emergency plans focus on coasts

As Hurricane Florence approaches the U.S. coast, over a million people have been ordered to evacuate from barrier islands and low-lying areas from South Carolina to Virginia. Precautions like this have been part of common hurricane preparations since the 1950s.

Coastal residents also prepare for major storms by building homes elevated above anticipated high water levels, in order to minimize damage and qualify for flood insurance. And building codes commonly call for reinforced construction to endure high wind speeds.

All of these sensible and essential preparations focus on wind and storm surge in coastal zones. Today, however, risk from hurricanes is extending inland. Some of the worst damage from Eastern Seaboard hurricanes in the past several decades has come from inland flooding along rivers after storms move ashore. Hurricane evacuations typically direct coastal residents to retreat inland, but river flooding can put them at risk if shelters and accommodations are not situated safely.

Much of my research, including my book, “Southern Waters: The Limits to Abundance,” has focused on the complex historical geography of water in the American South. What I have seen is that inland river flooding linked to hurricanes and heavy storms is a huge risk in the Southeast, but receives far less attention in emergency plans than coastal areas.

Warm, rainy watersheds
The U.S. Eastern Seaboard is particularly susceptible to river flooding due to tropical weather that moves onshore. From New England to Georgia, a dense network of rivers flows down from the eastern Appalachians across the Piedmont – a broad, rolling plateau extending from the mountains to the coastal plain – and drains into the Atlantic Ocean. Steep gradients move water quickly down the mountain slopes.

On the Piedmont, many small streams merge and then become meandering rivers on the low-lying coastal plain. When tropical weather systems lumber onshore and move inland, they rise up the steep face of the Blue Ridge Mountains. As the saturated air moves upward, it cools and releases huge quantities of rain – a process known as orographic precipitation.