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Robert Dalrymple: Get Ready for Extreme Weather

Katrina was just the beginning. The long, hot summer that is global warming will be characterized by rising water levels, unprecedented coastal erosion, and more Category 5 hurricanes. Robert Dalrymple, a coastal engineer at Johns Hopkins University, warns that the nation is woefully unprepared. They said Katrina was a 100-year storm but then, so was Rita a month later, he says. What does that tell you? Dalrymple offers the next president a three-point plan to prepare for the coming era of marine mayhem. How to Avert Disaster 1. Plan the Evacuation If another huge storm strikes tomorrow, we need to know how to beat a timely retreat. Emergency officials say we must be able to empty vulnerable cities like Miami, New Orleans, and Charleston in 24 hours. Most probably couldn't come anywhere close to that goal as recent history demonstrates. The main bottleneck, Dalrymple says, is transportation. Remember the evacuation of Houston during Hurricane Rita? Cars were stuck for miles along the freeway. What's needed, he says, is a reverse-laning system that could be implemented at the push of a button, converting all lanes of traffic into a one-way super-highway out of town. 2. Restore the Wetlands Coastal marshes and swamps provide a natural buffer against ocean storms, absorbing floodwaters like giant sponges. Given that Louisiana has lost more than 1,900 square miles of coastal wetland in the past century, the devastation of New Orleans by Katrina in 2005 was all but inevitable. Because the Mississippi has been so extensively dredged and channelized, it shoots all the sediment needed to sustain these areas right out into the Gulf, Dalrymple says. Current efforts to fortify the city's levees won't be enough. His solution: Reroute the river to aim the waterborne soil where it's needed. That wouldn't be cheap, but the alternative is even less palatable. How to Avert Disaster Click for full-size image. 3. Save the Beaches Beaches are another crucial storm buffer. But those sandy strands are disappearing, putting heavily populated regions like the mid-Atlantic at risk. The erosion is particularly severe around jetties and inlets, which alter shore currents. Seawalls built to fend off the encroaching waters only make things worse. The quickest and often the only practical solution, Dalrymple says, is to just pick up the sand from where it collects and haul it back to where it came from. An operation at the Indian River Inlet in Delaware is using a massive portable eductor (a dredging pump) to suck up offshore sand deposits. Dalrymple says we need to build more such units and put them to work soon. Robert Dalrymple is Professor of Civil Engineering at Johns Hopkins University.