North-central Iowa has a large number of private water wells due to no rural water provider in the area. New wells are being installed at an increasing rate and the number of large agricultural and livestock wells is increasing. Larger wells put more strain on aquifers and have the potential to cause interference with private wells in their vicinity. Understanding the lithostratigraphy helps contribute to the delineation of aquifers which can be put into best practice managements. Other geologic information adds to the understanding of water quality. The thickness of Quaternary material has been shown to have a robust effect on the levels of groundwater contaminants. Confining units, like glacial till, impede the flow of surficial water to contaminate groundwater aquifers. Mapping the extent of these packages can help rural Iowans with groundwater issues.
This data was collected from water wells and analyzed by Iowa Geological Survey geologists. I coded the data to fit both lithologic and stratigraphic uses. The table generated was a point file with elevations attached to it. For this project, I have reworked this information by interpolating between points to generate thicknesses of the Quaternary package (depth to bedrock), elevations of the formations, and the elevation of the bedrock surface. The bedrock surface was based on hand-drawn lines that I compiled from 5 different mapping projects in the area then interpolated between them using additional well information. Reclassing them and converting the files to polygons allowed me to use them as web based files.
The thickness of the quaternary package is a key piece in predicting where groundwater contamination could occur.
Aquifers are determined by the lithology of the bedrock. Tracking the elevations of these formations helps accurately predict how deep wells need to be drilled. Areas where the formations are not present are due to the the erosion of the layer
The elevation of the bedrock shows the general trend of both modern and paleo drainage networks. This is a crucial component to generate depth to bedrock values as well as formation elevations. The difference in surface elevation and bedrock elevation give depth to bedrock (Quaternary thickness) and the intersection of formation rasters the zero isoline.
The water well point file used to generate the rasters is shown here projected based on elevation.