Publication Date
April 2018
Abstract
The Ohio Geological Survey has mapped karst in Ohio since 2009. Field mapping of sinkholes has suggested that geomorphological parameters vary between the Bellevue, Delaware, Hillsboro, and Springfield karst regions. Statistical tests confirm that these parameters distinguish the four regions. An understanding of how they differ and what causes those differences can be used to better manage these karst features. Differences between sinkholes within each region were quantified using nine parameters derived from digital elevation model (DEM) analysis. These parameters included: depth, perimeter, area, volume, length of major and minor axes, eccentricity, circularity index, and orientation of karst features. Of these parameters, orientation was displayed on rose diagrams and the others were graphed on boxplots. The Conover-Iman (CI) test was used to determine if parameters were statistically distinct (α=0.05) between karst regions. Bellevue has the largest sinkholes in the state and differs statistically from other regions by perimeter, area, volume, major axis, and minor axis. Delaware has the deepest sinkholes, and depth is statistically distinct from all other regions except Springfield. Springfield has the smallest number of sinkholes, and no parameter distinguishes Springfield from all other regions. Hillsboro has the smallest mean sinkhole size, but the most sinkholes. Sinkholes in Hillsboro are also statistically more circular than other regions as shown by eccentricity, and circularity index. Three of the four karst regions show alignment with structural lineaments. The exception is the Hillsboro region, where sinkholes are very circular and exhibit no preferred orientation. Variations in sinkhole size, shape, and distribution are influenced by multiple factors. For example, dissolution in the four regions is influenced by bedrock type, with increasing solubility from dolomite to limestone to evaporites. Sinkholes in Bellevue may be highly developed because Bellevue is underlain by evaporites. Bellevue also experienced multiple events that likely lead to increased bedrock fracturing and water availability from melting ice. Conversely, most of Hillsboro was glaciated only once and has less-developed sinkholes. Unlike other regions, Bellevue was affected by ancient lakes as well. Large sinks in Bellevue indicate higher dissolution activity and sinkholes that have merged, while small circular sinkholes in Hillsboro are less active and not developed enough to merge and become irregular. Improved knowledge of the differences between these regions will assist in mitigating and avoiding these geologic hazards.
Rights Information
DOI
https://doi.org/10.5038/9780991000982.1021
Quantitative Comparison of Sinkhole Geomorphology of Four Karst Regions in Ohio
The Ohio Geological Survey has mapped karst in Ohio since 2009. Field mapping of sinkholes has suggested that geomorphological parameters vary between the Bellevue, Delaware, Hillsboro, and Springfield karst regions. Statistical tests confirm that these parameters distinguish the four regions. An understanding of how they differ and what causes those differences can be used to better manage these karst features. Differences between sinkholes within each region were quantified using nine parameters derived from digital elevation model (DEM) analysis. These parameters included: depth, perimeter, area, volume, length of major and minor axes, eccentricity, circularity index, and orientation of karst features. Of these parameters, orientation was displayed on rose diagrams and the others were graphed on boxplots. The Conover-Iman (CI) test was used to determine if parameters were statistically distinct (α=0.05) between karst regions. Bellevue has the largest sinkholes in the state and differs statistically from other regions by perimeter, area, volume, major axis, and minor axis. Delaware has the deepest sinkholes, and depth is statistically distinct from all other regions except Springfield. Springfield has the smallest number of sinkholes, and no parameter distinguishes Springfield from all other regions. Hillsboro has the smallest mean sinkhole size, but the most sinkholes. Sinkholes in Hillsboro are also statistically more circular than other regions as shown by eccentricity, and circularity index. Three of the four karst regions show alignment with structural lineaments. The exception is the Hillsboro region, where sinkholes are very circular and exhibit no preferred orientation. Variations in sinkhole size, shape, and distribution are influenced by multiple factors. For example, dissolution in the four regions is influenced by bedrock type, with increasing solubility from dolomite to limestone to evaporites. Sinkholes in Bellevue may be highly developed because Bellevue is underlain by evaporites. Bellevue also experienced multiple events that likely lead to increased bedrock fracturing and water availability from melting ice. Conversely, most of Hillsboro was glaciated only once and has less-developed sinkholes. Unlike other regions, Bellevue was affected by ancient lakes as well. Large sinks in Bellevue indicate higher dissolution activity and sinkholes that have merged, while small circular sinkholes in Hillsboro are less active and not developed enough to merge and become irregular. Improved knowledge of the differences between these regions will assist in mitigating and avoiding these geologic hazards.
