Geology topics
R.E. Hansen
Publications and source records attributed to R.E. Hansen.
Availability and quality of water from the alluvial, glacial-drift, and Dakota aquifers and water use in southwest Iowa
A ground-water resources investigation was conducted in southwest Iowa to describe the availability, quality, and use of water from the alluvial, glacial-drift, and Dakota aquifers in a nine-county area. Historical water quality was examined for each aquifer, and water samples were collected for major ions, trace metals, radionuclides, and selected pesticides. Selected aspects of surface-water resources in the study area also were examined to more fully evaluate alluvial aquifers. The flood plain of the Missouri River valley was not included except for the accounting of the water use in the area. Four principal alluvial aquifers consisting of sand and gravel deposits in the valleys of the Nishnabotna, Tarkio, Nodaway, and One Hundred and Two Rivers are present. Yields to wells have been reported as large as 2,000 gallons per minute; however, most yields are less than 100 gallons per minute. Nitrate concentrations greater than the drinking-water regulation and agricultural herbicides have been detected in 6 of 27 samples from municipal water supplies. Four types of glacial-drift aquifers are present-loess, inter-till sand and gravel, basal sand and gravel, and buried-channel aquifers. The glacial-drift aquifers are most commonly used by rural water users or users that do not have access to alluvial aquifers. These aquifers are discontinuous and unpredictable in location. Hydraulic and water-quality data generally are unavailable for these aquifers. Wells completed in loess commonly yield less than 10 gallons per minute, although there are reports of yields as large as 20 gallons per minute. Yields of 10 to 120 gallons per minute appear to be possible for inter-till and basal sand and gravel aquifers. Yields of more than 150 gallons per minute are possible from some buried-channel aquifers. The Dakota aquifer is comprised of bedrock of Cretaceous age and is present as erosional remnants and outliers in several counties, mainly Cass and Montgomery. Yields of more than 150 gallons per minute to wells completed in the Dakota aquifer have been reported, although yields of 20 gallons per minute or less are more typical. The drinking-water regulation for nitrate has been exceeded in some samples from the Dakota aquifer. The quantity of water withdrawn for municipal, rural-domestic, livestock, and other permitted water users was determined for each of the three principal aquifer types. The total water use within the study area was about 91.8 million gallons per day; 35.3 percent was from alluvial ground-water sources. Alluvial aquifers supplied most of the water from ground-water sources. The largest use of water is for permitted irrigation purposes, mostly from the Missouri River alluvial aquifer.
Bedrock topography of west-central Iowa
Bedrock in Iowa (Hershey 1969) generally is overlain by deposits of glacial drift and alluvium. The drift, consisting of glacial till and glacial outwash, ranges in thickness from zero to more than 500 feet in western Iowa; the alluvium in stream valleys ranges in thickness from less than 1 to more than 70 feet. The configuration of the bedrock surface is the result of a long period of preglacial erosion and during shorter, but more intense, periods of interglacial erosion. This map, for a 12-county area in west-central Iowa, is the eighth of a series of nine reports that will provide statewide coverage of the bedrock topograhy of Iowa.
Bedrock topography of northwest Iowa
Bedrock in Iowa (Hershey, 1969) generally is overlain by deposits of glacial drive and alluvium. The drift, consisting of glacial till and glacial outwash, ranges in thickness from zero to more than 500 feet in western Iowa; the alluvium in stream valleys ranges in thickness from less than 1 foot to more than 70 feet. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses that were developed during a long period of preglacial erosion. This map, for a 12 county area in west-central Iowa, is the eighth in a series of nine reports that will provide statewide coverage of the bedriock topography of Iowa.
Water resources data Iowa, water year 1985
Water resources data for the 1985 water year for Iowa consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; ground-water levels and ground-water quality. This report contains discharge records for 111 stream-gaging stations; stage and contents for 8 lakes and reservoirs; water quality for 8 stream-gaging stations; sediment records for 12 streamgaging stations; water levels for 94 observation wells; and chemical analyses for 214 observation wells. Also included are 118 crest-stage partial-record stations. Additional water data were collected at various sites, not part of the systematic data-collection program, and are published as miscellaneous measurements and analyses. The data represent that part of the National Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Iowa.
Bedrock topography of central Iowa
The bedrock in Iowa (Hershey, 1969) generally is ovelain by deposits of glacial drift and alluvium. The drift, comprised of glacial till and glacial outwash, varies in thickness from less than 1 foot to more than 400 feet; the alluvium in central Iowa varies in thickness from less than 1 foot to about 60 feet. The configuration of the bedrock suface is the result of a complex system of ancient drainage courses which were developed during a long period of preglacial erosion and during shorter, but more intense, periods of interglacial erosion. This map, for a 10 county area in central Iowa, is the seventh of a series of 9 reports that will provide statewide coverage of the bedrock surface of Iowa.
Bedrock topography of northwest Iowa
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Water resources data Iowa, water year 1984
Water resources data for the 1984 water year for Iowa consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; ground-water levels and ground-water quality. This report contains discharge records for 115 gaging stations; stage and contents for 7 lakes and reservoirs; water quality for 17 gaging stations; and water levels for 90 observation wells. Also included are 120 crest-stage partial-record stations. Additional water data were collected at various sites, not part of the systematic data-collection program, and are published as miscellaneous measurements and analyses. The data represent that part of the National Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Iowa.
Bedrock topography of central Iowa
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Bedrock topography of west-central Iowa
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Bedrock topography of north-central Iowa
The bedrock in Iowa (Hershey, 1969) is generally overlain by deposits of glacial drift and alluvium, which range in thickness from less than 1 ft to more than 400 ft, and from less than 1 ft to about 60 ft respectively. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses which were developed during a long period of preglacial erosion and during shorter, but mroe intense, periods of interglacial erosion.
Bedrock topography of north-central Iowa
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Geohydrology of Muscatine Island, Muscatine County, Iowa
Muscatine Island is a wide segment of the west bank of the Mississippi River flood plain that covers about 50 square miles in Muscatine and Louisa Counties; the project area encompasses the 30 square miles in Muscatine County. The flood plain is underlain by thick, permeable alluvial deposits that comprise a water-table aquifer that is developed extensively for water supplies in the area. The aquifer consists principally of sand and gravel, interbedded with lenses of silt and clay. Its saturated thickness ranges from about 40 to 140 feet. The transmissivity and storage coefficients of the aquifer range from about 20,000 ft. 2 /day and 0.15. respectively, in the western part of the Island to about 39,500 ft.2/day and 0.24 in the eastern part. The amount of water stored in the aquifer, under normal conditions, is about 100 billion gallons. Discharge from the aquifer is principally by pumpage, which has increased from about 1 mgd (million gallons per day) in 1906 to about 37 mgd in 1970. About 2.5 mgd is normally lost to seepage and evapotranspiration along a 9-mile reach of Muscatine Slough in Muscatine County. About 0.9 mgd is discharged by evaporation from gravel pits. Recharge to the aquifer is by induced infiltration from the Mississippi River, seepage from the river during major flood events, precipitation, and seepage from the underlying limestone bedrock. Induced infiltration provides about 80 to 85 percent of the water withdrawn from the principal pumping centers along the river and also replaces about 70 to 80 percent of the water that is evaporated from the gravel pits; this amounted to about 30 mgd in 1971. Additional significant recharge from the river occurs during major floods, when prolonged high stages provide the head for considerable underflow to the aquifer. Recharge from precipitation on the Island was calculated to average about 6inches per year or about 0.3 mgd per square mile. Seepage from bedrock is significant and is attributed to the increased head differential between the alluvial and bedrock aquifers in the areas of major pumping. The chemical constituents of water from the aquifer are generally within the recommended limits established by the U. S. Public Health Service for drinking water. Stresses on the hydrologic system have affected the position and configuration of the water table and the chemical quality of the ground water. The large-scale withdrawals, which began at the principal pumping centers in 1946, have caused the water table to decline from about 1 foot in the interior of the Island to about 5 feet near the edges of the main pumping centers; the decline was more than 8 feet under the pumping centers. A slight increase in hardness of water from riverward wells in the pumping centers is attributed to the induced infiltration of slightly harder river water; a noticeable increase in hardness and iron content in water from landward wells is attributed to seepage of water from the bedrock. In the central irrigated area, which is underlain by very permeable, highly drained soils that are mulched with organic fertilizers, the nitrate content of the ground water is as high as 46 mg/l (milligrams per liter). Land-use practices have had, and probably will continue to have, an impact on the quality and quantity of water available in the system. The hydrologic system in 1971 was in dynamic equilibrium or in near-equilibrium with the stresses imposed on it to that date. This equilibrium would be disturbed by any additional stresses on the system and water levels would change until a new equilibrium was established. The effects of future stresses can be reasonably predicted by developing a digital model of the system. The data to develop such a model are available in this report. Continued and expanded monitoring of water levels would provide data for better model verification. Periodic monitoring of nitrate and other chemical constituents would permit early detection of changes in concentration before the concentrations reached excessive levels.
Bedrock topography of northeast Iowa
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Bedrock topography of east-central Iowa
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