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Ground-water Recharge
Recharge is the addition of water to the underground reservoir and may be accomplished in several ways. In Chase County local precipitation is the principal source of recharge, and lesser amounts are contributed by influent seepage from streams and ponds and by subsurface inflow from adjacent areas.
Recharge from Precipitation
In Chase County the normal annual precipitation is about 32 inches. The greatest amount occurs in the months of April to September, inclusive, during the growing season. The normal annual precipitation amounts to more than 500,000,000 gallons of water per square mile, but only a small part of this quantity reaches the zone of saturation. Of the precipitation, a part runs off directly, a part is discharged by evaporation and transpiration, and a part is added to (recharges) the ground-water reservoir, later being discharged into streams or by evaporation and transpiration.
Runoff, including both direct runoff and groundwater discharge into streams, accounts for only a small part of the precipitation except after prolonged or very heavy rains. According to records of the Division of Water Resources of the Kansas State Board of Agriculture, the annual net runoff in the drainage area of the Cottonwood River above Cottonwood Falls, Kansas, during the five years 1939 to 1943, inclusive, ranged from 0.96 inch in 1940 to 11.59 inches in 1941, and the average for the five-year period was 3.47 inches. If related to the precipitation records at Cottonwood Falls for the same period of time, a runoff of approximately 11 percent of the precipitation is indicated; this figure is probably somewhat higher than the average for a longer period of time because of the exceptionally high precipitation and runoff in 1941.
The amount of water lost by transpiration and evaporation depends upon the temperature, humidity, vegetative covering, wind velocity, depth to the water table below land surface, and the length of time the processes of evaporation have access to moisture. In Chase County the bulk of the water that does not run off into the streams, averaging probably a little less than 29 inches, is lost by transpiration and evaporation.
Seepage from Streams and Ponds
Streams contribute recharge to the unconsolidated alluvial material during times when stream level is above the level of the adjacent water table. After periods of flood, the water table in the alluvium of Cottonwood River valley and its major tributaries is frequently several inches to several feet higher than before the flood. The water, however, discharges rather quickly back into the streams after their levels decline.
Intermittent tributary streams, where they cross exposed permeable strata in the upland areas, contribute to the recharge of the stratified Permian rocks where structural conditions are suitable--that is, where the permeable strata dip away from, rather than toward, the contributing stream.
Ponds and lakes in the upland areas contribute small amounts of recharge, mostly to the surficial permeable rocks below the pond or lake but to some extent to permeable stratified rocks. The amounts contributed to the stratified rocks, however, are small.
Percolation from Outside the Area
Ground-water recharge by subsurface percolation in either the consolidated stratified rocks or unconsolidated rocks, or both, enters Chase County from adjacent areas. The amount of ground water added to the subsurface reservoirs by this means, however, is small. Also, it probably is balanced by water leaving the county in the same way.
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Kansas Geological Survey, Chase County Geohydrology
Placed on web March 2001; originally published Aug. 1951.
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