News Release, Kansas Geological Survey, March 5, 2008
LAWRENCE--Groundwater levels rose in south-central Kansas this year as levels in the western part of the state continued a downward trend according to preliminary data compiled by the Kansas Geological Survey (KGS), based at the University of Kansas.
In January 2008, ground-water levels in a network of more than 1,400 wells were measured by the KGS and the Division of Water Resources (DWR) of the Kansas Department of Agriculture. For the entire network, the average water level rose slightly--0.005 feet based on preliminary estimates--from the year before. In contrast, the average level had dropped a little more than a foot for the entire network between January 2006 and 2007.
The January 2008 levels, however, varied significantly from east to west as unusually high increases in south-central Kansas offset declines to the west.
"The increases and decreases are mainly precipitation driven," said Brownie Wilson, the Survey's water-data manager. "Precipitation in south-central Kansas was 150% to 200% above normal in 2007 and greater than average at key times during the growing season. Some places in the southwest currently have moderate drought conditions while the rest of the area is abnormally dry."
In the short run, precipitation fluctuations influence irrigation withdrawal more than they affect the amount of water recharging the aquifer, Wilson said. More rainfall means less water is taken out for irrigation.
In south-central Kansas, water levels in the Great Bend Prairie aquifer area rose 3.1 feet. In the Equus Beds aquifer north of Wichita, they rose 2.04 feet. In comparison, between 2006 and 2007 they dropped 1.19 feet and 2.39 feet, respectively.
"The rises in ground-water levels in south-central Kansas are the biggest we've recorded since the Survey started administrating the program in 1996," Wilson said.
In western Kansas, where water is pumped primarily from the Ogallala aquifer portion of the High Plains aquifer, declines were greatest in the southwest. There, levels dropped an average of 1.65 feet between 2007 and 2008.
During the same time period, water levels in a stretch of west-central Kansas from Wallace to Lane counties dropped an average of 1.1 feet. In the northwest corner of the state, from Cheyenne to Graham counties, they dropped 0.91 feet.
The year before, average declines were 2.45 in the southwest, 0.73 in the west-central counties, and 0.27 in the northwest.
In January 2007 western Kansas had heavy snows that hampered well measurement efforts but provided little in the way of recharge.
"Snow melt provides soil moisture reserve, but that only lasts so long by itself," Wilson said. "By May the pattern of precipitation was well below normal."
Results of the measurements are provisional and subject to revision based on additional analysis. The measurement data will be available by mid March at http:/www.kgs.ku.edu/Magellan/WaterLevels/index.html.