| Abstract: | A 3-D finite difference digital model was used to simulate groundwater flow in the 25,000 sq mi aquifer system of the North Carolina Coastal Plain. The model was developed from a geohydrologic framework that is based on an alternating sequence of 10 aquifers and 9 confining units, which comprise a seaward-thickening wedge of sediments that form the Coastal Plain aquifer system in North Carolina. The model was calibrated by comparing observed and simulated water levels. The maximum transmissivity of an individual aquifer in the calibrated model is 200,000 sq ft/d in a part of the Castle Hayne aquifer, which is composed predominately of limestone. The maximum simulated vertical hydraulic conductivity in a confining unit was 2.5 ft/d in a part of the confining unit overlying the upper Cape Fear aquifer. Analysis indicated the model is highly sensitive to changes in transmissivity and leakage near pumping centers; away from pumping centers, the model is only slightly sensitive to changes in transmissivity but is moderately sensitive to changes in leakance. Recharge from precipitation to the surficial aquifer ranges from about 12 in/yr in areas having clay at the surface, to about 20 in/yr in areas having sand at the surface. Most of this recharge moves laterally to streams, with only about 1 in/yr moving down to the confined parts of the aquifer system. Groundwater level declines, which are the result of water taken from storage, are extensive in some area and minimal in others. Water level declines exceeding 100 ft have occurred in the Beaufort County area because of withdrawals for a mining operation and water supplies for a chemical plant. Head declines have been less than 10 ft in the shallow surficial and Yorktown aquifers and in the updip parts of the major confined aquifers distant from areas of major withdrawals. A water-budget analysis using the model simulations indicates that much of the water removed from the groundwater system by pumping ultimately is made up by a reduction in water leaving the aquifer system, which discharges to streams as base flow. |
| Genre: | USGS Numbered Series |
| ProdID: | 19080 |
| Citation Author: | Giese, G. L.; Eimers, J. L.; Coble, R. W. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | - |
| Citation Editor: | |
| Citation End Page: | |
| Citation Issue: | |
| Citation Keywords: | |
| Citation Language: | ENGLISH |
| Citation Larger Work Title: | |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | xiii, 178 p. :ill. ;28 cm. |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | Dept. of the Interior, U.S. Geological Survey ;
Books and Open-File Reports [distributor], |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 90-372 |
| Citation Search Results Text: | Simulation of ground-water flow in the coastal plain aquifer system of North Carolina; 1991; OFR; 90-372; Giese, G. L.; Eimers, J. L.; Coble, R. W. |
| Citation Start Page: | |
| Citation Volume: | |
| Citation Year: | 1991 |
| Type: | citation/reference |
| Text: | Simulation of ground-water flow in the coastal plain aquifer system of North Carolina; 1991; OFR; 90-372; Giese, G. L.; Eimers, J. L.; Coble, R. W. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/usgs_thumb.jpg |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | Dept. of the Interior, U.S. Geological Survey ;
Books and Open-File Reports [distributor], |
| Superseded by: |
http://pubs.er.usgs.gov/publication/pp1404M
|
