Granite Geek: Rain, rain don’t go away and you can come again another day

  • The Contoocook River flows up to its banks as it crosses downtown Contoocook on Monday, July 12, 2021. GEOFF FORESTER—Monitor staff

  • This chart from scacis.rcc-acis.org shows accumulated shortfall of precipitation in Concord. The brown line is the long-term average; green line is accumulated precipitation (rain and melted snow) since May 1, 2020, when the current dry spell began. NOAA—Courtesy

  • The Contoocook River flows over the dam in downtown Contoocook on Monday, July 12, 2021. GEOFF FORESTER—Monitor staff

  • The Merrimack River is up to its banks on Monday, July 12, 2021 compared to last year. GEOFF FORESTER—Monitor staff

  • The Contoocook River flows up to its banks as it crosses downtown Contoocook on Monday, July 12, 2021. GEOFF FORESTER—Monitor staff

  • The Contoocook River flows up to its banks as it crosses downtown Contoocook on Monday, July 12, 2021. GEOFF FORESTER—Monitor staff

  • A person walks in a downpour on Storrs Street last Friday as the remnants of Tropical Storm Elsa moved through the Concord area. GEOFF FORESTER / Monitor staff

  • The Merrimack River is up to its banks on July 12, 2021. GEOFF FORESTER / Monitor staff

  • A spillway into the Merrimack River in Penacook on Sept. 17, 2020. Monitor file

Monitor staff
Published: 7/12/2021 4:16:57 PM

Every time I plan to write about our drought, it rains.

Last week as I discussed the state’s long dry spell with Ted Diers, administrator of the state’s watershed management bureau, Tropical Storm Elsa was dumping almost 2 inches of rain on my house. As I type this, an unnamed storm is following up with another inch or more.

It’s hard to think about drought when you’re worried about basement flooding. But this little paradox is actually appropriate because a wet spell has less to do with drought than it seems, especially when it involves a heavy downpour that runs off into rivers more than it soaks into the ground.

“This is great, super helpful, this is amazing, but it’s probably not going to put us out of drought. It will fill up the lakes, give some relief to fish in the river, and you’re going to have to mow the lawn,” Diers said. “But this isn’t going to help groundwater much at all.”

Much of New Hampshire has been in a drier-than-usual spell since May 2020, although it’s much worse in the North Country, where Diers says some stream gauges have recorded the lowest flow on record. The state has reinstated a well-replacement fund for low-income individuals who’ve lost their home water supply.

Such geographic variation isn’t unusual, Diers noted: “Because of the way the jet stream works and elevational changes, this state has a lot more climate than most small states.”

As for Concord, it has gotten almost three inches of rain this month, as can be seen by looking at the Contoocook or Sun cook rivers, which are popping right now. The Merrimack River is much bigger and so heavily controlled by dams that it doesn’t fluctuate as much.

So the drought’s over, right? Alas, no.

Since May 1, 2020, Concord has had 9 inches less precipitation (rain and melted snow) than normal: 41 inches vs. the expected 50 inches. July has been very wet, cutting the deficit by almost four inches, but that hasn’t made up for a long-term shortfall, especially with so much of the recent deluge racing downstream toward the ocean. In particular, it takes weeks or even months for groundwater to seep down into the bedrock where most wells draw their water these days, so while recent rain might help boaters and swimmers, it’s not going to do much for aquifers.

(A quick note: An aquifer is just a layer of sand, gravel or rock that’s permeable to water that oozes through cracks or among the aggregate. Many of us think it’s a lot more impressive than that: “I have people who call me and say, ‘My water comes from an underground river,’ ” said Diers.)

As of Friday, low levels in groundwater systems had led 87 public water systems – some as small as a single mobile home park and others as large as Pennichuck Water covering greater Nashua – had imposed some sort of restriction, usually limiting outdoor watering. That affects more than 330,000 people. The current wet weather is unlikely to change that number much unless it continues steadily.

Designations for things like “abnormally dry” and moderate through exception drought are based not just on recent rainfall but on groundwater measurements, agriculture reports and stream flows, among other items. If you’d like to keep track of how things are going – maybe you’re tired of fixating on the state’s COVID-19 dashboard – the state DES has a drought page with enough links to maps and charts for the most data-hungry among us: www.des.nh.gov/climate-and-sustainability/storms-and-emergencies/drought.

Diers says the current drought is a reminder that although New England is a pretty wet place overall, we need to be prepared, especially in view of the recent shocking heat wave and wildfires in western Canada, which is just as wet and cool as we are.

“We should be planning for more challenges – we should also be becoming more resilient,” he said. Happily, we have.

“We’ve gotten a lot better at using water efficiency over the last 20 years,” Diers said. “I was looking at projections from the 1990s. Back then, we were talking about doubling water use. But in many communities, water use went down over that period of time … even as they grew. That’s because we’ve gotten better at using water.”

However, we are going to need to do better still. Cities need to fix water system leaks and decrease stormwater runoff so more of it soaks into the ground. We need to reduce or redesign those “impermeable surfaces” (buildings, parking lots, roads) that keep rain out of aquifers. We all need to be prepared to use less water inside our homes and on our lovely but useless lawns if the need arises. 

And there’s one more possibility that comes to mind as I look out my home-office window at an overflowing rain barrel: Maybe I need to write about drought more often.




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