Characterization of surface water/groundwater interactions along a coastal plain river / by Patrick Kolt Johnson.
| Author/creator | Johnson, Patrick Kolt author. |
| Other author | O'Driscoll, Michael (Michael Anthony), degree supervisor. |
| Other author | Mallinson, David J., degree supervisor. |
| Other author | East Carolina University. Department of Geological Sciences. |
| Format | Theses and dissertations |
| Production | 2007. |
| Description | 215 leaves : illustrations (some color), maps (some color) ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The interactions between Coastal Plain rivers and their underlying groundwater systems have important implications for water resource management, yet these interactions are not well-known. The Tar River, located in eastern North Carolina, is a Coastal Plain river with an asymmetrical river valley; the river is commonly located at the extreme southern flank of its valley. This results in a common pattern of steep bluffs and narrow floodplains to the south of the river, and broad floodplains to the north side of the river. Significant differences in slope, elevation, sediment type, and riparian zone river connection exist between the north and south sides of this river. The study objective was to quantify river-groundwater interactions along the Tar River and determine if differences in river-groundwater interactions exist across and along the river channel. Physical hydrograph separations and statistical analysis of long term discharge (1931-2003) indicated that baseflow (groundwater) comprised an average of 60% of the Tar River streamflow. Streamflows were found to be susceptible to seasonal weather patterns. Floodplain and river channel sediments adjacent to the river along a 22 kilometer reach were characterized with split spoon cores and hand auger samples. Ground penetrating radar was used to define the shallow stratigraphic framework. Sediments on the north side of the river are typically fine to coarse reworked fluvial sands. Sediments on the south are typically Pleistocene and older marine sands and clays. The Snow Hill Member of the Black Creek Formation and the Yorktown Formation are sloping regional confining units that underlie the Tar River in western and eastern portions of the field area, respectively. The lateral flow of groundwater towards the Tar River atop these confining units is likely. Hydraulic conductivity calculated from channel piezometer data showed that surficial materials on the north side were approximately 19 times higher than on the south side. Sediment samples and slug tests conducted in stream-channel piezometers also indicated that the geology between the north and south sides of the river varied significantly. Annually, the river typically gained groundwater, but losing conditions also existed during the 2005-2006 study period. Typically, losing conditions became more common when river discharge fell below 500 cfs. Annual average groundwater flux for the north side was higher than the south side. Ground penetrating radar was found to be useful in locating sub-channel horizons including channel sands, bedforms, and confining units. Groundwater flux near the stream channel likely occurs as lateral flow atop confining beds and at much higher rates on the north side. Consequently, the movement of contaminants through the unconfined aquifer and into the Tar River is likely to occur at higher rates on the north side. The City of Greenville uses the Tar River as its primary source of potable water. With increasing water demands, alternative water sources and progressive management strategies like aquifer storage and recovery (ASR) may be necessary to sustain projected development while maintaining streamflows. |
| General note | Presented to the faculty of the Department of Geological Sciences. |
| General note | Advisor: Michael A. O'Driscoll |
| General note | Advisor: David J. Mallinson |
| Dissertation note | M.S. East Carolina University 2007 |
| Bibliography note | Includes bibliographical references (leaves 83-86. |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |