We should prepare for the next flood, even during drought

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Drive through any part of New England today and you'll see signs of drought: brown grass, wildfire warnings, early fall foliage and low rivers. One hundred percent of New Hampshire, Vermont and Maine is experiencing drought, with drought and abnormally dry conditions stretching into Massachusetts, Connecticut and Rhode Island.  Over the past three months, northern New England has only received about one-half of its normal rainfall due to storms tracking farther south than usual.  

The impacts of the current drought are extensive — dairy farmers are buying feed to compensate for dry pastures, burn bans are in place throughout the region and towns from southern Maine to Cape Cod are restricting water use. Yet, as we rightly manage these impacts, we shouldn't lose sight of the more pressing climate hazard in New England: floods.

New England always has and always will experience drought, but the number and severity of droughts has actually decreased over the last 40 years. Research conducted by my group looking at climate records going back to 1901 found that since 1983, there have been 50% fewer droughts in the Northeast, and the droughts that did occur have been less intense.  

Why did drought decrease? More rain. Droughts are caused by a lack of water at the surface, including in lakes, rivers, soils and vegetation, like a bathtub with very little water. Drought is controlled by the balance between rainfall — water flowing into the tub from the faucet — and evaporation from soils and plants to the air — water flowing out of the tub through the drain. The total amount of rain and snow has increased across the Northeast by approximately 10% over the past 30 years. Temperatures have also been getting warmer, which can cause more evaporation, but to date the increase in rainfall has kept the tub full more often.

As drought has decreased, heavy rainfall across the Northeast has dramatically increased. During the past three decades, we have experienced 45% more heavy rainfall from storms that drop about two inches or more in a 24-hour period. While most of these storms do not cause substantial flooding, some do. This past summer, damaging floods hit Vermont on July 10 for the third year in a row, and just two days later intense thunderstorms washed out roads in southeastern New Hampshire.  

Looking to the future, the Northeast is likely to experience more total rainfall and heavy rainfall, according to predictions by climate models. The flooding we've seen in recent years is the new normal.

To help blunt the effects of drought, we should provide more aid to farmers who are already operating on thin margins, tighten restrictions to prevent wildfires (unfortunately including Dartmouth's homecoming bonfire) and continue reducing our water usage. But at the same time, we should be getting ready for the next flood. Research consistently shows that preparing for floods reduces impacts and saves money — which is all the more important given FEMA's uncertain future. So, how should we prepare? 

First, reduce the number of people in harm's way. Stop building in areas that have been shown to flood whether they are mapped by FEMA or not, and move homes and businesses already in floodplains to safer locations with voluntary buyouts. 

Second, increase the resilience of infrastructure. Upsize and clean out culverts. Identify roads, homes and bridges that are vulnerable to damage by floodwaters scouring their foundation — something our current flood risk maps can't do. And design to today's floods as opposed to the storms of the past. 

Third, strengthen communities throughout New England. Create emergency funds, bolster community service organizations and encourage collaborations across small towns and between urban and rural areas to identify flood protection strategies that do, and don't, work.  

Finally, expand emergency preparedness.  Install more rain and streamflow monitoring. Develop better alert systems and raise community flood awareness so that everyone knows what to do when an alert is issued.

And while we do all of that, let's keep our fingers crossed for some rain, but not too much.

Jonathan Winter is an associate professor at Dartmouth College who studies climate change and climate impacts on water, agriculture, and health.

Photo Credit: Michael Dwyer / AP