Report
Geologic Hazards Mapping: Identifying Sinkholes and Karst Susceptible Areas In Worth, Cerro Gordo, Mitchell, and Floyd Counties
Iowa Geological Survey Technical Information Series, Vol.59
Iowa Geological Survey
03/2021
DOI: 10.17077/rep.006582
Abstract
The Iowa Geological Survey (IGS) updated the sinkhole coverage and karst susceptibility map for a four-county area in north-central Iowa including Worth, Cerro Gordo, Mitchell, and Floyd counties (Figure 1). Results more than doubled the number of mapped sinkholes and significantly refined the karst susceptibility map for the region. This work was enhanced due to recent surficial and bedrock geologic mapping completed by the IGS as part of the United States Geological Survey (USGS) STATEMAP program. These recent geologic maps improved upon the Bedrock Geologic Map of Iowa (Witzke et al., 2010) and provided the basis for determining areas with bedrock that typically form karst features and sinkholes. The surficial geologic maps allowed IGS geologists to consider the characteristics of surficial geologic materials when identifying areas with high karst potential, whereas previous karst assessments had only considered the thickness of surficial materials.
The IGS evaluated the location and accuracy of data points in the IGS GeoSam database. A series of horizontal to vertical spectral ratio (HVSR) passive seismic points were also collected to check the depth to bedrock in areas of limited data. The 25 foot contour bedrock elevation map produced by previous mapping efforts was adjusted as necessary, but did not warrant a complete remap of the bedrock topography. During the evaluation of the sinkhole data, it was noted that the identified sinkholes took on numerous surficial expressions. The IGS utilized electrical resistivity (ER) methods to investigate the subsurface character of several sinkholes with different land uses and surficial material cover. As part of the study, the newly produced sinkhole coverage was used to validate the karst susceptibility maps.
Details
- Title: Subtitle
- Geologic Hazards Mapping: Identifying Sinkholes and Karst Susceptible Areas In Worth, Cerro Gordo, Mitchell, and Floyd Counties
- Creators
- Stephanie A Tassier-Surine - University of Iowa, IIHR--Hydroscience and EngineeringPhillip Kerr - University of Iowa, IIHR--Hydroscience and EngineeringRyan J Clark - University of Iowa, IIHR--Hydroscience and EngineeringCalvin F Wolter - University of Iowa, IIHR--Hydroscience and EngineeringJason Vogelgesang - University of Iowa, IIHR--Hydroscience and EngineeringAllison Kusick
- Resource Type
- Report
- Publication Details
- Iowa Geological Survey Technical Information Series, Vol.59
- DOI
- 10.17077/rep.006582
- Publisher
- Iowa Geological Survey; Iowa City, Iowa, USA
- Number of pages
- ix, 74 pages, 29 figs., 2 tables
- Copyright
- Publication of the State of Iowa. This publication is a public record.
- Comment
- Final Report (May 1, 2019 to March 31, 2021). Project Number HR-3018. Conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration.
- Language
- English
- Date published
- 03/2021
- Academic Unit
- Iowa Geological Survey; IIHR--Hydroscience and Engineering; Technical Information Series
- Record Identifier
- 9984399859002771
Metrics
62 File views/ downloads
109 Record Views