Walk in the Prairie

September 25, 2004, our group walked in this area observing features of Cheyenne Bottom prairie, marshes and drainage system to control level of water.

A 41,000-acre natural land sink, Cheyenne Bottoms was formed by geological forces about 65 million years ago; some 100,000 years ago, after river-borne sediments filled in the basin, it became a freshwater marsh. Today, the bottoms reflect years of shaping by human activity. Nine man-made, interconnected pools each cover more than 700 acres. Roughly 50 percent of the bottoms is privately owned and consists of native-grass pasture and cropland planted with wheat, Milo, and alfalfa (Hands, 1998).

In a marsh, the water level naturally fluctuates. In the bottoms, it can go from bone dry to five feet deep, as happened in 1992. Annual precipitation averages twenty-four inches, but in a typical year, even more water is lost to evaporation. Yet after a heavy rain, the water level can rise by as much as ten inches overnight. Such fluctuations help check the growth of dense stands of cattails, trees, and herbaceous plants, such as millet and dock (Hands, 1998).

Cheyenne Bottoms' natural sources of water--runoff, precipitation, and two creeks that flow into the basin--have been supplemented since the 1950s by flows diverted from the Arkansas River and one of its tributaries, Walnut Creek. These sources proved unreliable, however; starting in about 1970, the once-healthy marsh began suffering from water shortages, which led to the spread of cattails and the subsequent loss of open mudflats. As a result, shorebird numbers in the bottoms began a long decline (Hands, 1998).

An important turn about came in 1992 when, after a severe drought, a landmark court decision ordered cutbacks in irrigation near Great Bend to allow more water to reach Cheyenne Bottoms.  The fight to keep mudflats clear of invading cattails continues. With favorable weather, large tractors to mow these tenacious plants, and persistence will hopefully reclaim more of the mudflats for the benefit of shorebird travelers.

"Although evapotranspiration from marsh vegetation is in balance with rainfall, water lost from native grasses in the surrounding prairies exceeds precipitation by 3inches, about 60 inches is lost each year by evaporation from open water surface.  This water deficit is lessened by the flows of Blood and Deception creeks into Cheyenne Bottoms, but this is a limited asset since their combined collecting basins total a mere 105 square miles.  Accordingly, this surface flow is often less than 20 percent of the import from direct rainfall" (Zimmerman, 1990).

Walking in the area, we observed features typical for both wetlands and prairie.

Drainage stream and dam to keep water level adequate in marshes
Marshes leading to the dam.  Water is very shallow.
Dragonfly in prairie
Cactus in wetlands
Sedge is a typical plant for wetlands
Prairies dogs are inhabitants of wetlands

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