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Ground-water Resources, continued
Recharge of Ground Water
Addition of water to an aquifer is known as ground-water recharge. The main source of recharge in Miami County is the precipitation which falls on the county. Some water enters the county by movement in the subsurface from adjacent areas, and some recharge is contributed by streams.
Recharge from Precipitation
Only a small percentage of the water that falls as precipitation on Miami County reaches the ground-water reservoir. Most of it runs off as surface water or returns to the atmosphere through evaporation and transpiration. The rate of precipitation, type of soil, character of underlying rocks, amount and type of vegetation, and configuration of the topography all affect the rate and quantity of recharge.
Probably the most favorable conditions for recharge in Miami County occur in the alluvium and upper Pleistocene terrace deposits of the Marais des Cygnes River valley. In some localities the silt and clay of these deposits may retard recharge to some extent, but water levels in wells in the Marais des Cygnes valley rise relatively quickly after moderate to heavy rainfall.
Pennsylvanian rocks have diverse recharge characteristics because of local geologic, structural, and topographic conditions. In areas underlain by thick sequences of shale, recharge is very low, but where limestone or sandstone are exposed, conditions are favorable for substantial recharge. Over large areas of Miami County, limestones are at or near the surface and recharge probably occurs through fractures and joints in the rock. Fluctuations in the discharge of springs from limestone aquifers in the county coincide with wet or dry periods, indicating a considerable amount of recharge and rapid horizontal movement of water in these rocks. Precipitation entering small sinkholes in the upper part of the Wyandotte Limestone in eastern Miami County moves downward through solution channels and fractures and is largely discharged by springs in the same general area. It is reported that response to precipitation is so rapid in some of the springs discharging from limestones in eastern Miami County that the issuing water becomes turbid soon after a heavy rain.
Recharge from Adjacent Areas
Subsurface movement of water from outside the county is a relatively unimportant source of recharge to the ground-water reservoir. Some ground water probably moves into the county in the northeastern part along structural lows that trend southwest. Minor amounts of ground water probably enter along the eastern edge of the county from Missouri.
Recharge from Streams
Temporarily, during periods of high water in the Marais des Cygnes River, some water probably enters the alluvial aquifer from the stream. However, as soon as the stage of the stream drops below the level of the water table in the aquifer, the direction of water movement is reversed, and the water is discharged from the aquifer into the stream.
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Kansas Geological Survey, Miami County Geohydrology
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Web version June 2002. Original publication date June 1966.
URL=http://www.kgs.ku.edu/General/Geology/Miami/08_gw2.html