Ground Water, continued
RechargeThe amount of water in storage in the zone of saturation does not remain constant but fluctuates with the precipitation and rate of withdrawal. Recharge is the addition of water to the ground-water reservoir and may be accomplished in several ways.
All ground water in Sumner County originally fell as rain or snow within the county or in adjacent areas. Water reaches the zone of saturation in Sumner County by direct recharge from local precipitation, by recharge from streams and ponds, and by subsurface movement from outside the area.
Recharge from Local PrecipitationThe normal annual precipitation in Sumner County is about 31 inches, but only a small part of this amount enters the zone of saturation as recharge to the ground-water reservoir. A large part of the precipitation is evaporated or is transpired by plants, and a small part leaves the county as surface runoff.
The relation of water levels to precipitation is illustrated by the hydrographs in Figures 5, 6, and 7. The initial abrupt decline of water level in some of the Mulvane wells is caused by the beginning of pumping of the El Dorado-Augusta Water Association wells. In this area generally, water levels declined in 1954, rose sharply in 1955 in those months when the precipitation was near or above normal, and declined in 1956 when precipitation was considerably below normal. Normal or above-normal precipitation in the spring of 1957 resulted in a sharp rise in water level in most observation wells, although pumping by the El Dorado-Augusta Water Association continued at a nearly uniform rate until May 15.
Percolation from Outside AreasThe movement of ground water into Sumner County is, in general, southeastward from Harper, Kingman, and Sedgwick Counties. There may be some movement westward in the westward-dipping Permian rocks, which are exposed at the surface in the area to the east, but not many wells in Sumner County obtain water from these rocks. The amount of water entering the county by subsurface movement probably is only slightly greater than the amount that leaves the county by this means.
Seepage from Streams and PondsTwo factors governing the amount of water seeping into the ground-water reservoir from streams and ponds are (1) the level of the water in the stream or pond relative to the level of the ground water and (2) the character of the material between the stream channel or pond and the water table. The water-table contours show that most streams in Sumner County are effluent (Fig. 8); that is, normally the streams receive water from the ground-water reservoir. During periods of flood, the water level in the streams is higher than the level of the ground water, hence water moves from the streams into the ground-water reservoir. In areas of local heavy pumping near a stream, the water table may be lowered to such an extent that the natural flow is reversed, and water moves from the stream into the groundwater reservoir. This is especially noticeable in the Chikaskia River valley at the Caldwell municipal wells. During periods of drought when Chikaskia River ceases flowing, the yield of the municipal wells is greatly decreased; when the river begins to flow again, the yield of the wells returns to normal although there may have been no local precipitation.
Figure 8--Diagrammatic sections showing influent and effluent streams (after O.E. Meinzer).
If the material between a stream channel or pond and the water table is relatively impermeable, the rate of downward percolation may be so slow that the amount of recharge by this means is negligible. The alluvium of Bluff, Slate, Salt, and Fall Creeks is relatively impermeable, and recharge from them would be small even though the water level in the streams might be high enough to permit recharge. The alluvium of Cowskin Creek and of Ninnescah, Chikaskia, and Arkansas Rivers is fairly permeable and would permit rapid recharge. A heavy coating of algae and contaminating material on the stream floor of Arkansas River undoubtedly impedes recharge from this stream considerably. Most farm ponds in Sumner County have been constructed purposely in relatively impermeable material so that recharge from them is small.
Kansas Geological Survey, Sumner County Geohydrology|
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Web version January 2003. Original publication date August 1961.