| Abstract: | A compilation of regional ground-water divides for the five principal aquifers corresponding to the Great Lakes Basin within the United States is presented. The principal aquifers (or aquifer systems) are the Cambrian-Ordovician aquifer system, Silurian-Devonian aquifers, Mississippian aquifers, Pennsylvanian aquifers, and the surficial aquifer system. The regional ground-water divides mark the boundary between ground-water flow that discharges to the Great Lakes or their tributaries and ground-water flow that discharges to other major surface-water bodies, such as the Mississippi River. Multicounty to multistate (regional) hydrologic studies of the five principal aquifers were reviewed to determine whether adequate data, such as potentiometric surfaces or ground-water divides, were available from which ground-water flow directions or ground-water-divide locations could be derived. Examination of regional studies indicate that the regional ground-water divides for the Cambrian-Ordovician aquifer system and Silurian-Devonian aquifers have changed over time and differ from the surface-water divides in some areas. These differences can be attributed to either pumping or natural processes. The limited information on the shallow Mississippian and Pennsylvanian bedrock aquifers indicate that these aquifers and the surficial aquifer system act as one hydrostratigraphic unit and that downdip flow is insignificant. Generally, in the Mississippian and Pennsylvanian aquifers, regional ground-water divides are similar to regional surface-water divides. Previous studies of the regional ground-water divide of the surficial aquifer system depict the regional ground-water divide as generally following the regional surface-water divide.
Because studies commonly focus on areas where ground-water use from an aquifer system is concentrated, the regional ground-water divides are not known in large, unstudied parts of some of these aquifer systems. A composite ground-water divide for the region was generated and is estimated to generally follow the surface-water divide, except in areas where anthropogenic or natural factors affect its position. |
| Genre: | USGS Numbered Series |
| ProdID: | 77026 |
| Citation Author: | Sheets, R. A.; Simonson, L. A. |
| Citation Contributing Office: | USGS National Water Availability and Use Program |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | Revised Jan 2008 |
| Citation Editor: | |
| Citation End Page: | |
| Citation Issue: | |
| Citation Keywords: | |
| Citation Language: | ENGLISH |
| Citation Larger Work Title: | |
| Citation LatN: | 0500000 |
| Citation LatS: | 0360000 |
| Citation LonE: | -0700000 |
| Citation LonW: | -1000000 |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 27 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | iv, 23 p. |
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| Citation Public Comments: | |
| Citation Publisher: | Geological Survey (U.S.) |
| Citation Series: | Scientific Investigations Report |
| Citation Series Code: | SIR |
| Citation Series Number: | 2006-5102 |
| Citation Search Results Text: | Compilation of Regional Ground-Water Divides for Principal Aquifers Corresponding to the Great Lakes Basin, United States; 2006; SIR; 2006-5102; Sheets, R. A.; Simonson, L. A. |
| Citation Start Page: | |
| Citation Volume: | |
| Citation Year: | 2006 |
| Type: | citation/reference |
| Text: | Compilation of Regional Ground-Water Divides for Principal Aquifers Corresponding to the Great Lakes Basin, United States; 2006; SIR; 2006-5102; Sheets, R. A.; Simonson, L. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/usgs_thumb.jpg |
| URL (INDEX PAGE): | http://pubs.usgs.gov/sir/2006/5102/ |
| Date Other: | Thu, 13 Jul 2006 00:00 -0500 |
| Publisher: | Geological Survey (U.S.) |
