Geology topics
Research about Iowa
Source-linked reports with geographic coverage including Iowa.
Flood of June 27, 1975, in City of Ames, Iowa
On June 27, 1975, the city of Ames and vicinity sustained severe flooding from Squaw creek and the south Skunk River. The storm which preceded the flood was net particularly outstanding in its intensity or duration. However, antecedent conditions plus the timing and direction of the storm were "ideally tuned" to cause the flood. In terms of magnitude of discharge as well as of damages this was the most severe flood on record, with losses estimated by city and Iowa State University officials at over a million dollars. The most unfortunate loss involved the drowning of a young person. The peak discharge at the Squaw Creek station, 206 mi 2 (534 km 2 ), was measured at 11,300 ft 3 /s (320 m 3 /s), which is 1.6 times the 100-year flood. The south Skunk River above the confluence with Squaw creek, 315 mi 2 (816 km 2 ), peaked at 5,330 ft 3 /s (151 m 3 ). The recurrence interval of this discharge is 6.0 years. The peak discharge on the South Skunk River below the confluence with Squaw creek, 556 mi 2 (1440 km 2 ), was 14,700 ft 3 /s (416 m 3 /s), which is 1.1 times the 100-year flood.
Bedrock topography of northeast 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 foot (0.3 m) to more than 400 ft (18 m), respectively. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses when were developed during a long period of preglacial erosion and during shorter, but more intense, periods of interglacial erosion.
Resources data for Iowa, water year 1974; Part I, Surface water records
Explore the source record for details and available documents.
Water resources data for Iowa, water year 1974; Part II, Water quality records
Water resources data for the 1974 water year for Iowa including records of streamflow or reservoir storage at gaging stations, partial-record stations, and miscellaneous sites, and records of water-quality data on the chemical and physical characteristics of surface and ground water, are given in this report. In Part 1, records are included for 127 gaging stations of which 119 are streamflow discharge stations, and 8 are reservoir or lake stations; also included are records for 426 low-flow partial-record stations, 128 crest-stage partial-record stations, and 30 miscellaneous sites. Locations of gaging stations are shown in Figure 2. In Part 2, water quality data on chemical, physical, biological, and sediment characteristics of surface water were collected from designated sampling sites at predetermined intervals such as once daily, weekly, monthly, or less frequently. Records are given for 353 sampling stations of which 23 are continuous record stations, 9 are partial-record stations, and 321 are miscellaneous sites. Locations of water-quality stations are shown in Figure 3. A summary of periodic water temperature data is given for 98 regular gaging stations. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of S.W. Wiitala, district chief. These data represent that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Iowa.
Land classification of south-central Iowa from computer enhanced images
The author has identified the following significant results. Two enhanced false color negatives from multispectral scanner scenes, dated 15 April 1974 and 29 August 1972, were printed at a scale of 1:125,000 to form the basis for land use interpretations in the Wapello County, Iowa test site. The use of geomorphic principles proved valuable in the interpretation of the April scene to form valuable generalizations for planning purposes on soil associations, topography, alluvial valleys, and agricultural land use. The August scene was superior in providing information on urban extent, transportation networks, forest cover, and water bodies.
Phosphatic zone in the lower part of the Maquoketa Shale in northeastern Iowa
The basal beds of the Maquoketa Shale in northeastern Iowa include a basal silty phosphorite layer that is thickest near Dubuque. In Clayton County, Iowa, the bed averages about 1 foot thick (30 centimeters) and contains 22.5 percent P 2 0 5 . Phosphatic dolomite that is 8 10 feet (2.4 3 meters) thick and occurs higher in the Maquoketa was observed only in Dubuque County. The thickest and most phosphatic rock in the Maquoketa appears to be coextensive with dark-brown shale, which also occurs mainly in Dubuque County. Rare-earth content of the phosphatic rock decreases southeastward across the area, ranging from 2,000 to about 120 parts per million. The thin low-grade phosphorite is typical of the platform-type phosphorite facies and may be' genetically related to the emergence of the Ozark uplift as an island late in the Ordovician period.
Bedrock topography of south-central Iowa
The bedrock surface in Iowa is covered nearly everywhere by unconsolidated deposits of glacial drift and alluvium which range in thickness from less than 1 foot to more than 400 feet, and from less than 1 foot to about 60 feet, respectively. The bedrock surface is the result of a complex system of ancient drainage courses, which were developed during the long period of preglacial erosion and during shorter, but more intense, periods of interglacial erosion.
Bedrock topography of southeast Iowa
The bedrock in Iowa is covered nearly everywhere by unconsolidated deposits of glacial drift and alluvium, which range in thickness from less than 1 foot to more than 400 feet, and from less than 1 foot to about 60 feet, 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 more intesne periods of interglacial erosion.
Floods in the Iowa River basin upstream from Coralville Lake, Iowa
Flood information is reported for 207 miles of the main stem, 23 miles on the West Branch, and 23 miles on the East Branch, of the Iowa River. The information will be of use to those concerned with the design of bridges and other structures and the conduct of various operations on the flood plains of the streams. Included in the report are flood-peak records, gaging-station records, and water-surface profiles. Outstanding floods treated in this report are the 1954 flood which is the greatest known in the upper reaches of the Iowa River, the 1969 flood which is the greatest flood in recent years in the central reach of the river, and the 1947 flood which is the greatest flood recorded, excepting the 1918 historic flood, in the lower reaches of the river. Selected data are also given for the 1918 flood, the greatest flood recorded on the Iowa River. Flood profiles for the main stem include those for the 1947, 1954, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1972 flood. On the West Branch Iowa River, profiles are shown for the 1944, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1954 flood. On the East Branch Iowa River, profiles are shown for the 1954, 1969, the computed 25- and 50-year floods, and a partial profile for the June 1944 flood. Low-water profiles are shown for all reaches.
Flood of August 2, 1972, in the Little Maquoketa River basin, Dubuque County, Iowa
Flood peaks with magnitudes from 2 to 3 times the SO-year flood occurred on streams in the Little Maquoketa River basin for the flood of August 2, 1972. Up to nine inches of rain fell in the headwater of the Middle Fork tributary with six to seven inches occurring over most of the Little Maquoketa River basin. The flood peak elevation at the gaging station near Durango exceeded the 1925 flood of record by 1.7 feet. Flood damages were extensive to crops, roads, and bridges. Many of the homes in Durango, Daytonville, and Sageville were inundated to some extent and were evacuated. Flood damages were estimated to be over one million dollars. No loss of life or personal injuries were sustained. Flood-peak discharges at 12 sites, basin rainfall, a description of the 1972 flood, brief accounts of other major floods in the basin, maximum flood peaks in northeastern Iowa, selected flood-frequency data, and annual floods of record at 5 sites are given.