Browsing by Subject "aquifer"

Now showing 1 - 8 of 8
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    Aquifer and Stratigraphy Code Prediction Using a Random Forest Classifier: An Exploration of Minnesota’s County Well Index
    (2021-05) Thielsen, Chris
    We live in an era of big data, brought on by the advent of automatic large-scale data acquisition in many industries. Machine learning can be used to take advantage of large data sets, predicting otherwise unknown information from them. The Minnesota County Well Index (CWI) database contains information about wells and borings in Minnesota. While a plethora of information is recorded in CWI, some objective codes are missing. A random forest classifier is used to predict aquifer and stratigraphy codes in CWI based on the data provided in drillers’ logs; i.e., before the strata are interpreted by a geologist. We find that by learning from the information written down by the well driller, stratigraphic codes can be predicted with an accuracy of 92.15%. There are 2,600,000 strata recorded in CWI; these codes are not only useful in understanding the geologic history of Minnesota, but also directly inform groundwater models.
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    C-28 Geologic Atlas of Renville County, Minnesota [Part A]
    (2013) Setterholm, Dale R.
    Surface and subsurface geology of Renville County, Mn. includes bedrock topography and depth-to-bedrock
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    C-30 Geologic Atlas of Wright County, Minnesota [Part A]
    (2013) Tipping, Robert G.
    Surface and subsurface geology of Wright County, Mn. includes bedrock topography and depth-to-bedrock. Additional data added 2015; raster data sets of the elevation of the top and bottom, and the thickness of bedrock units in Wright County.
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    C-31 Geologic Atlas of Morrison County, Minnesota [Part A]
    (2014) Lusardi, Barbara A.
    Surface and subsurface geology of Morrison County, Mn., including bedrock topography and depth to bedrock
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    C-32 Geologic Atlas of Sherburne County, Minnesota [Part A]
    (2013) Lusardi, Barbara A.
    Surface and subsurface geology of Sherburne County, Mn., including bedrock topography and depth to bedrock
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    An Enclosing Analytic Element
    (2019-02) Ausk, Bonnie
    The main contributions described in this thesis are two-fold: 1. A new analytic element for a closed boundary of a chosen shape that may contain internal elements. The element, referred to as the enclosing analytic element, is valid for steady three-dimensional flow. We outline the general method for constructing these new analytic elements and provide several examples: (1) an elliptic enclosing element, (2) a square enclosing element, (3) a rectangular enclosing element, and (4) a slotted enclosing element. We combine the enclosing analytic element with other established analytic elements via superposition, including uniform flow, recharge, wells, line-sinks, and elliptic lakes. 2. A new technique for expanding the original shape into a family of shapes. Each new shape within the family set results in a reduction in the sharpness of the corners. We refer to these new shapes as smooth boundary shapes.
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    OFR14-05, A HYDROCHEMICAL SURVEY OF GROUNDWATER FLOW IN THE ROCHESTER METROPOLITAN AREA, MINNESOTA
    (Minnesota Geological Survey, 2014) Tipping, Robert G.
    Historical chemical and isotopic data from Olmsted County, Minnesota were used to distinguish groundwater types based on similar chemical and isotopic composition. The extent of recent waters, identified by detectible tritium, chloride, nitrate or sulfate concentrations above background levels, along with groundwaters having elevated calcium to magnesium molar ratios were mapped in three dimensions. The distribution of these waters can be explained, in part, by the permeability of unconsolidated sediments overlying bedrock, bedrock hydrostratigraphy, and vertical hydraulic gradients within the Rochester Central Metropolitan Area (RCMA) dueto high capacity pumping. The spatial distribution of groundwater chemical types is also a function of changes in vertical hydraulic gradients with time. Within the last 20 years, the extent of recent waters within the RCMA has expanded both horizontally and vertically. Groundwater calcium to magnesium ratios in the Prairie du Chien Group (Shakopee aquifer) and the Jordan Sandstone (Jordan aquifer) within the RCMA have also increased and show greater variability through time, indicating a greater percentage of recharge to these aquifers moving vertically within the RCMA and from the Decorah edge than before high-capacity pumping began.
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    OFR18-03, Core Descriptions, Borehole Geophysics, and Unit Interpretations in Support of Phase I and II USGS Hydrologic Properties of Till Investigation
    (Minnesota Geological Survey, 2018) Staley, Amie E; Wagner, Kaleb; Nguyen, Maurice; Tipping, Robert
    This report summarizes the contributions of the Minnesota Geological Survey (MGS) to a three-year study conducted in two phases – Environmental and Natural Resources Trust Fund (ENRTF), M.L. 2014, Chp. 226, Sec. 2, Subd. 03h, and ENTRF, M.L. 2016, Chp. 186, Sec. 2, Subd. 04h, led by the United States Geological Survey (USGS) Minnesota Water Science Center, which seeks to further knowledge on the sources and rates of recharge to confined aquifers set within buried-valley sequences in Minnesota. Six cores (including one collected for a previous study) of unconsolidated Quaternary deposits were extracted from known confined glacial aquifer settings, in four regions across Minnesota, in order to target variability in the material properties of the aquitards that confine them.