The Kansas River Corridor--Its Geologic Setting, Land Use, Economic Geology, and Hydrology

by Lawrence L. Brady (compiler), David A. Grisafe, James R. McCauley, Gregory C. Ohlmacher, Hernán A. M. Quinodoz, and Kenneth A. Nelson

Released as Kansas Geological Survey Open-file Report 98-2, January 1998

Executive Summary

• The Kansas River corridor is the major source of sand and gravel for northeastern Kansas. Sand and gravel is obtained either by river dredging or pit dredging in the floodplain. The river dredges produce some of the best-quality and least-expensive sand in the United States. In October 1997, nine dredges operated in the Kansas River, all on the middle to lower portion of the river where conditions normally favor river dredging. In 1996, the Kansas River dredges produced about 2.4 million tons of sand and gravel worth about $8 million, which generated nearly $357,000 in sand royalties to Kansas. In addition, seven pit dredges operate within the Kansas River floodplain.

• In general, the lower portion of the Kansas River (Topeka and below) favors river dredging while the upper portion of the river favors pit dredging. The broader floodplain, the lower price for land, thinner overburden, and thick usable sand and gravel deposits favor pit dredges along the upper part of the river. Scarcity of land due to the narrow floodplain and commercial/industrial development, significant overburden thickness relative to the thickness of available sand and gravel, and a more dense population with political opposition to extractive industries are the main reasons river dredges are preferred in the lower part of the Kansas River. A river dredge requires about 10 acres (4 ha) of land for the processing plant. By contrast, a pit dredge needs about 100 acres (40 ha) of land for the plant, dredging acreage, and land for overburden stockpiles. Studies along the entire river floodplain, based on physical limitations alone, have identified 74 potentially profitable pit-dredging locations, with 49 of the 74 in Pottawatomie, Wabaunsee, and Shawnee counties.

• The river valley averages 2.6 miles (4.2 km) in width over its 138-mile (220-km) length. The widest stretch of the river valley is between Wamego and Rossville, where it is up to 4 miles (6.4 km) wide. Below Eudora, the valley narrows significantly to less than 1.5 miles (2.4 km) and in parts of this reach the valley is 1 mile (1.6 km) or less in width.

• Included in the Kansas River corridor study area are 1,700 square miles (4,400 km²) that include all or part of six of the 10 largest cities in the state. Today the population of the 10 counties in the study area is estimated at about 40 percent of the state's total. Most growth between the 1980 and the 1990 census occurred in Johnson County, with Douglas, Leavenworth, Shawnee, and Riley counties showing substantial gains.

• Grassland, with a coverage of 45 percent, and cropland, at 28 percent coverage, are the two most extensive landcovers in the corridor area. In the floodplain area itself, cropland cover is 60 percent while grassland is second with 14 percent coverage. The combined land-use categories of commercial/industrial and residential, which includes most of the developed areas, represents 7 percent of the floodplain and 9 percent of the corridor area.

• Use of alternate sources such as sand from the Kansas River tributaries, or Missouri River sand west of Kansas City, would result in increased sand and gravel prices because of larger transportation costs, which average about $0.10 per ton mile. A moratorium on river dredging with only pit dredges on the Kansas River floodplain would also increase sand prices, particularly in the lower portion of the Kansas River where demand is highest and potential pit-dredge locations scarce.

• Based on population trends, a long-term demand for both sand and gravel and crushed stone aggregates should continue. Population projections suggest that by the year 2025, nearly half of the Kansas population will reside in the 10 counties along the Kansas River. Planners and decision-makers need to ensure that adequate long-term supplies of sand and gravel and crushed stone are available to meet future demands for aggregates along the Kansas River corridor.

• The Kansas River is a dynamic system carrying water and sediments. The sediment-carrying capacity of the river is a function of precipitation, sediment supply, channel characteristics, and velocity of the water. Because these parameters are highly variable, the sediment-carrying capacity is also highly variable. The sediment-carrying capacity of the river has been estimated in previous studies to be in the range of one to two million tons of sand per year. However, predictions of sediment-carrying capacity are subject to significant uncertainty, which should be taken into account when making decisions and considering alternative policies.

• To minimize potential damage that might be caused by a substantial lowering of the bed elevation in the Kansas River, the U.S. Army Corps of Engineers placed restrictions on the amount of sand and gravel that is allowed to be dredged from certain river reaches and limited the amount of annual sand and gravel production within 15-mile (24-km) zones along the river. This plan was phased in gradually between 1991 and 1994. Restrictions on production of Kansas River sand and gravel in the Kansas City area have been offset by sand-dredging activities in the Missouri River, but Missouri River sand contains a small amount of lignite, resulting in sand of a lower quality than sand from the Kansas River.

• In general, the stream channel of the Kansas River is considered to be in equilibrium or slightly degrading, that is, being deepened by erosion. Because of the effects of bedrock in the channel, gravel armoring, and backwaters from the Missouri River, Bowersock Dam, and the Johnson County water intake, several reaches lack degradation.

Acknowledgments

Considerable support was provided by Capt. Erik Blechinger while working on his research paper for the M.S. degree in Civil Engineering at The University of Kansas. He worked with several of the authors in reviewing available data and determining the economics for floodplain dredging potential along the Kansas River.

Kansas Geological Survey personnel important to various phases of review and development of the report include Dr. Lee Gerhard, Mr. Rex Buchanan, Dr. Pieter Berendsen, Ms. Marla Adkins-Heljeson, Ms. Patricia Acker, and Ms. LeaAnn Davidson.

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Kansas Geological Survey, Kansas River Corridor Study
Electronic version Jan. 13, 1998.
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