March 7, 2011 — March has started out wet, but a dry winter has left the area with a below-normal water table.
The area received 2.77 inches of rain Sunday, measured at the McCormick Observatory. This brought March up to 78 percent of normal rainfall for the month in a little more than 24 hours. But it has been relatively dry winter and there is a seven-inch rainfall deficit to overcome.
"We've had a very dry period in most of the state and particularly in the Charlottesville area," University of Virginia climatologist Philip J. Stenger said. "Only one of the last 11 months has had normal or above-normal precipitation, and that was September."
In February, 1.51 inches of rain were measured at the McCormick Observatory, well below the 3.20 inches considered normal for the month. In January, 0.97 inches were recorded, well below the 3.71 inches considered normal.
Water tables tend to recharge in the colder months, when plants are dormant and there is less evaporation. Because there is less demand for water from plants, the moisture can penetrate the ground. But with little precipitation during the winter, Stenger said some area monitoring wells are at or near record-low levels.
While plenty of storms approached the area this winter, Stenger said they were too far offshore, or moved to the north or south of Virginia, leaving Central Virginia with little benefit.
Last summer, rainfall was light and the region suffered an agricultural drought, in which there was enough moisture in the water table, but not enough rainfall for the crops, much less to seep into the ground.
This summer, Stenger said, could be grim.
"Municipal water levels could go down and wells could run dry. We could be seeing a widespread problem," he said. "During the growing season, plant uptake and evaporation tend to prevent rain from penetrating the soil. Combine this with increased use of water in the warm-weather months and we may see groundwater and stream levels go down in the warmer months."
These water levels could reach their lowest point in the fall.
Sunday's rain was exactly what was needed – a slow, steady rainfall that had a chance to soak into the ground.
"This was a significant event, but we probably need a few more like it to relieve concerns for the summer," Stenger said. "But as things warm up we will see more evaporation, so there is not a lot of time to lay in reserves."
Richard Hopkins, landscape supervisor at the University, is already preparing for a dry summer.
"We've learned from the previous droughts," he said.
He said the University would go to landscape water restrictions earlier this year, using non-potable water on the landscaping. Facilities Management has installed a 7,700-gallon cistern to store rainwater near Bryan Hall, and has another 10,000-gallon cistern near Observatory Hill. Both cisterns are full right now, but they are recharged with rainwater, which may be in short supply.
The University has been planting drought-resistant and native species to conserve water.
"The things we planted in the spring last year can handle a drought better and the things we put in two years ago will require a minimal amount of water," he said. "The older, established plants will be able to handle it."
While the more established plants can handle a water shortage, new landscaping, such as that installed at the Emily Couric Clinical Cancer Center, will need extra attention.
"If we go into a drought, we have to maintain it or we will lose it all," Hopkins said.
Then there's the landscaping for the new Alderman Road residence houses. The University already has the plantings, but they are being kept in a nursery setting, which will require less labor to keep them alive through a dry summer.
"If we have a drought and we plant in the fall, the plants will be going dormant, the temperatures are cooler and there is less evaporation," Hopkins said. "But we need to have a certain amount of landscaping for building occupancy and for erosion control, so we have to find a middle ground."