Extensive, lingering rains have turned much of Mississippi into a soggy mess while replenishing rivers and lakes and recharging groundwater stores.
Charles Wax, state climatologist at Mississippi State University, said 2007 was the worst year of the recent, multi-year drought the state experienced. The end came in 2008 when above-average rainfall came in August and heavy rains began in late November.
“Statewide, the first week of December 2008 averaged about 4.25 inches of rain with a range of 7.54 inches in the northeast to 2.94 inches in the north-central parts of the state,” Wax said. “The second week of December brought a statewide average of 7.82 inches of rain, ranging from a high of 9.05 inches in the lower Delta to 5.06 inches in the upper Delta. Only the coastal region of the state did not receive above-normal rain during this time.”
Wax attributed the wet fall and winter to the activity of fronts.
“Lots of warm and cold frontal passages through the state associated with upper-level troughs in the middle of the North American continent brought much of the rain,” Wax said. “The large events, such as the Jan. 5-6 rain, have been caused by stalled or stationary fronts across the state, with waves of low pressure developing along them and moving from southwest to northeast across the state.”
Nearly all areas of the state ended last year with above-average rainfall. The 2008 rainfall and the difference from average is given in inches for the following locations in DeSoto, Washington, Oktibbeha, Hinds, Adams, Hancock and Jackson counties:
• 59.70 at Lake Cormorant, 10.08 above average
• 57.82 at Stoneville, 6.53 above average
• 65.18 at MSU, 12.70 above average
• 59.60 at Jackson, 4.65 above average
• 61.28 at Natchez, 4.98 above average
• 65.70 at Bay St. Louis, 2.11 above average
• 55.85 at Ocean Springs, 6.98 below average
Wax said the state normally gets 5-6 inches of rain in January, but MSU got 4 inches of rain in two days and nearly all of the state received rain the first week of the year.
“Right now, the wettest part of the state is along an axis from about Vicksburg to Iuka, with the east-central region having the most rain locally,” he said.
This extensive rain is generally a good thing.
“For the first time in a couple of years, the rivers and lakes are filled, the soils are full of water, and surplus water is available for aquifer recharge,” Wax said. “This is not the growing season, and there is no need for the water right now, but getting it now restores the environment and puts us in good shape for drier conditions later in the year.”
Larry Oldham, soil specialist with the MSU Extension Service, said rain can stay on top of the soil, soak in or run off.
“Soils have a great ability to soak up a lot of water,” Oldham said.
“Clay particles can absorb up to 200 times their size.
The puddles found in yards and farmland and the local flooding seen around rivers and creeks result when soil has absorbed as much water as it can. Excess rainfall runs off and collects in low areas.
“Our soils are saturated now, and there is very little oxygen in the soil,” Oldham said. “This is not a problem while most of our plants are dormant or simply not growing, but as the weather warms up and plants start growing, they will need to have some air in the soil to live.”
Oldham said how long soils take to dry out depends on the type of soil; clay soils hold water the longest, and sandy soils dry out the fastest.
While recent rains are running off in most places because of saturated soils, some water fails to soak in because of soil compaction. Oldham said wet soil that is driven over or used extensively can be compacted, damaging the soil and preventing water from being absorbed.
“To solve a compaction problem, you have to wait until the soil is very dry and use implements to shatter those manmade pans,” Oldham said. “A vehicle that drives across wet soil leaves damage about 10 inches below the soil. This damage still exists even when the tire tracks are flattened out and the area looks smooth again.”