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Tuesday, April 17, 2012

Rhode Island Braces for Impending Drought

Click for larger image. (Courtesy of NOAA)

PROVIDENCE — The average Rhode Islander enjoyed our milder-than-usual winter. Record high temperatures were logged nearly every week from January through March, and daily temperatures rarely got close to average lows.
The high temperatures and lack of snow were an unexpected savings for municipalities that didn’t have to pay contractors or city/town employees to clear the white stuff from roads and parking lots, or buy road sand.
What a difference a few years make. 

In March 2010, a record 14.87 inches of rain soaked Rhode Island. Most of the deluge, and damage, was attributed to the Great Flood. Yet in March of this year, only 1.21 inches of rain fell, 72 percent below the average. April has been even drier. Less than a quarter-inch has registered at T.F. Green Airport, or nearly 90 percent below the average.
All that can change in an instant, but the extreme weather, as predicted by climate scientists, is presenting challenges for those who work and play in the outdoors.
While the warm, snow-less winter may have been a boon to economically strapped communities, that same lack of a deep-freeze, and slow infiltration of groundwater that the gradual melting of snow provides through the spring, have set the stage for some serious pest and water-supply-related problems to both Ocean State residents and farmers.
The situation has reached the point that the Rhode Island Water Resources Board has convened a statewide Drought Steering Committee. While we are not officially under drought conditions, all the indicators are pointing to a drought advisory being issued sooner, rather than later.
What makes a drought?
There are four thresholds that have to be crossed for the Drought Advisory Steering committee to issue an advisory:
• Precipitation levels have to be 65 percent below a two-month cumulative average. The mostly snow-less winter means that Rhode Island has experienced much lower-than-average precipitation amounts; 2012 yearly rainfall amounts through March were 7.5 inches lower than average, and may reach 9 inches below average by the end of this month. We’ve met, and crossed, this threshold.
• The second indicator of drought conditions is streamflow. This is measured through a combination of river and stream levels, volumes and pressure. To get to drought levels, streamflow indices must be below average for three consecutive months. Though we haven’t yet met these conditions, members of the steering committee are confident that when April’s streamflow numbers have been finalized this condition will have been met.
• Groundwater levels are the third indicator of drought conditions. The threshold for this indicator is two out of three months below normal. While this indicator hasn’t yet been met, in February one-third of U.S. Geological Survey testing wells in Rhode Island were below normal, and nearly all of them were below normal in March. Again, officials expect these conditions to be met when April’s numbers come in.
• The last indicator of drought conditions is thePalmer Z Short-Term Drought index, maintained by the National Oceanic and Atmospheric Administration (NOAA). The Palmer Z shows severe drought conditions throughout all of southern New England for February.
We’re not quite there yet, but all signs are pointing to a drought advisory being issued as soon as early May.
The winter that wasn’t
Warmer winter temperatures present some benefits to New England farmers, but the potential problems may outweigh those benefits.
Higher temperatures allowed farmers with greenhouses and high tunnels to continue to grow through the winter with much less fuel consumption for heating those structures. Milder temperatures could conceivably allow farmers to till soil and plant row crops earlier in the season, but most New England farmers know that spring weather is a fickle beast. Most will wait until there is no chance of an overnight freeze before thinking about any outdoor planting.
The lack of deep-freeze conditions in the tillable soil may also contribute to the earlier appearance of certain pests and blights. The normally subfreezing cold of New England winters can kill many insect larvae and blight, inducing molds and pathogens in the soil. One of Rhode Islanders favorite crops, sweet corn, is particularly susceptible to a blight called Stewart’s wilt.
The bacterium that causes the disease resides in the flea beetle that feeds on corn. Low enough winter temperatures kill the beetle and the pathogen, and a deep-freeze may completely eliminate the risk of Stewart’s wilt. An outbreak of the wilt may mean smaller harvests and decreased revenues for farmers, and higher prices for consumers.
Perennial crops, particularly fruit trees, benefit from the shorter days and sustained low temperatures during the winter. Measured in “chilling hours,” this dormancy is the time when plants’ energy is stored, building up for new growth, and farmers can prune, clone, graft and transplant without fear of sprouting. A warmer-than-normal winter may lead to fruit trees generating fewer, weaker buds, hindering fruit production from the start of the growing season.
Fire risk high
Most of the state is on high alert for forest and brush fires. Fires recently torched 5 acres in Tiverton and open space in Exeter and West Greenwich.
"It's dry as a bone," said Paul Dolan, deputy state forester for the state Division of Forest Environment. 
March 15 to May 15 is peak fire season. Until trees sprout leafs to shade arid spots, dry leaves can stoke bigger fires in wooded areas. Vernal pools and other leaf-covered areas are also drying out, pushing the risk of fires to its highest level.
Most fires, Dolan said, are started by cigarettes or poorly managed manmade fires. He's urging fire marshals across the state to reduce the number of permits for burning backyard brush. He's also concerned about this weekend's start of the fishing season and school vacation week, which bring more people outdoors.
Fortunately, cooler and humid ocean winds have helped prevent larger fires like those in New York and Connecticut. But with 55 percent of the state covered in forest land, the risk is still high for damage. "Until we get rain we're in a holding pattern," Dolan said.
What does this mean for Rhode Island farms?
Drought Steering Committee member Henry Meyer drew a stark distinction between northern and southern Rhode Island regarding water retention. (Dave Fisher/ecoRI News)Where your farm is located in the state has a lot to do with how difficult it may be to weather the impending drought.
Henry Meyer, who sits on the Drought Steering Commmittee and the South Kingstown Water Board, said, “Northern and central Rhode Island have significant reserves.”
Reservoirs in these parts of the state are near or at capacity, due to higher than normal precipitation in the autumn months, but, “Storage in southern Rhode Island is nearly impossible," Meyer said. "Water supply in these parts of the state is almost completely driven by groundwater levels and streamflow. This statewide drought is something that South County deals with almost yearly.”
Ken Ayars, director of the state Department of Environmental Management’s (DEM) Division of Agriculture and Drought Steering Committee member, said the timing of the dry weather has so far spared seasonal crops, most of which have yet to be planted. The dry soil may also delay the start of planting season or force farmers to divert water from ponds or streams to meet demand. Ayars also said he is getting requests from some farmers to dig deeper ponds to hold water for irrigation.
Farmers in Rhode Island, with some caveats, are exempted from DEM regulations concerning expansion of retention ponds, especially in wetlands areas. “The ability of farmers to deal with drought conditions is largely dependent on water conservation techniques already in place on the farm," Ayars said. "The most important thing is we try not to wait for the drought to implement the practice."
One area of concern for Ayars is the irrigation-dependent sod and nursery industry, which generates most of the state's revenue from crop sales. “The drought may cause delays in the time to market for these crops because the sod may take longer to grow, and trees and shrubs will have to be left in the soil longer before being removed for sale," he said.
A dry spring also presents additional pest problems.
Heather Faubert, research assistant in plant sciences at the University of Rhode Island College for Environmental and Life Sciences, stressed that, “Of much greater concern than insect pests is the lack of water. One 'insect' pest that I know to thrive under dry conditions is spider mites. Two-spotted spider mites and European red mites reproduce more quickly under hot, dry conditions. Spruce spider mites probably do as well.”