isolated wetlands - the groundwater connection...include carolina bays, pocosins, pine savannas,...

Background Although the ecological and functional value of wetlands in the landscape is well documented, there are still significant gaps in our knowledge of “isolated” wetlands, especially in regard to water quality and hydrology. The groundwater system serves as a hydrologic connection between isolated wetlands and traditionally navigable waters. Additionally, water quality transformations may occur between the surface and subsurface components of the isolated wetland. Understanding the impacts of alterations to isolated wetlands thus must be informed by an understanding of the role of groundwater. As part of a multi-disciplinary investigation of isolated wetlands, DWQ and USC are investigating the hydrology and water quality function of groundwater at eight isolated wetland sites in North Carolina and four in South Carolina. Results of this investigation show that all the wetlands in the study are connected to downgradient surface water via groundwater without significant impediment from intervening confining units or aquitards. Examination of the water quality data is underway to determine the chemical relationships and transformations that may occur in the water in these systems. Data Collection A Geoprobe drilling rig was used for coring and well installation – it is lightweight for use on soft soils, can access wooded areas, and allows for rapid assessment of geology. • 8 sites in NC, 4 in SC •44 geologic cores, 20’ to 60‘ in depth • 90 monitoring wells • Monthly water level collection for one year at all wells • 43 automatic water level data- loggers for one year • Water quality analysis quarterly for one year for: • Nutrients • Metals • TOC, DOC • 10 stream gages • Aquifer tests at three sites Typical Site Monitoring Well Data Logger Pumping Well 500 Ft Wells and Monitoring Geologic coring 500 Ft Wetland Upland Streamside Core location: Isolated Wetlands - The Groundwater Connection Background Information for Posters 245 and 246 June 2012 Acknowledgements • EPA Cooperative Agreement Number CD 95415809 and CWA Section 106 • Bladen Lakes State Forest • Turnbull Creek Educational State Forest • The Nature Conservancy • South Carolina Department of Natural Resources Tiner (2003), identified 29 wetland types that may be geographically isolated. These occur in depressions, on broad flats and on slopes. Examples found in the North Carolina Coastal Plain include Carolina bays, pocosins, pine savannas, limestone sinks, sandhill seeps, vernal pools, and wet pine flats. In Bladen, Horry and Marion Counties, geographically isolated wetlands are often associated with Carolina Bays and pine savannas. In Brunswick County there are several near an escarpment possibly associated with a former beach front. One DWQ study site in Brunswick County is an apparent lime sinkhole, another is a pine savannah. (Tiner, Ralph W., 2003, Geographically Isolated Wetlands of the United States, Wetlands, vol. 23 no. 3, September, 2003, pp 494-516) Bladen County, NC # # # # # # 10 Miles # # 10 Miles Brunswick County, NC Study site Study Locations 100 Miles NC Counties SC Counties Study area Horry County, SC 10 Miles Marion County, SC 10 Miles

Upload: others

Post on 24-Jan-2021

2 views

Category:

Documents

0 download

Report

Download

Embed Size (px):

TRANSCRIPT

BackgroundAlthough the ecological and functional value of wetlands in the landscape is well documented, there are still significant gaps in our knowledge of “isolated” wetlands, especially in regard to waterquality and hydrology. The groundwater system serves as a hydrologic connection between isolated wetlands and traditionally navigable waters. Additionally, water quality transformations may occurbetween the surface and subsurface components of the isolated wetland. Understanding the impacts of alterations to isolated wetlands thus must be informed by an understanding of the role ofgroundwater.

As part of a multi-disciplinary investigation of isolated wetlands, DWQ and USC are investigating the hydrology and water quality function of groundwater at eight isolated wetland sites in NorthCarolina and four in South Carolina. Results of this investigation show that all the wetlands in the study are connected to downgradient surface water via groundwater without significant impedimentfrom intervening confining units or aquitards. Examination of the water quality data is underway to determine the chemical relationships and transformations that may occur in the water in thesesystems.

Data Collection

A Geoprobe drilling rig was used forcoring and well installation – it islightweight for use on soft soils, canaccess wooded areas, and allows forrapid assessment of geology.

•8 sites in NC, 4 in SC

•44 geologic cores, 20’ to 60‘ in depth

•90 monitoring wells

•Monthly water level collection for one year at all wells

•43 automatic water level data-loggers for one year

•Water quality analysis quarterly for one year for:

•Nutrients

•Metals

•TOC, DOC

•10 stream gages

•Aquifer tests at three sites

Typical Site

Monitoring Well

Data Logger

Pumping Well

500 Ft

Wells and Monitoring Geologic coring

500 Ft

Wetland

Upland

Streamside

Core location:

Isolated Wetlands - The Groundwater ConnectionBackground Information for Posters 245 and 246

June 2012

Acknowledgements• EPA Cooperative Agreement Number CD 95415809 and CWA Section 106

• Bladen Lakes State Forest

• Turnbull Creek Educational State Forest

• The Nature Conservancy

• South Carolina Department of Natural Resources

Tiner (2003), identified 29 wetland types that may be geographically isolated. These occur in

depressions, on broad flats and on slopes. Examples found in the North Carolina Coastal Plain

include Carolina bays, pocosins, pine savannas, limestone sinks, sandhill seeps, vernal pools,

and wet pine flats. In Bladen, Horry and Marion Counties, geographically isolated wetlands are

often associated with Carolina Bays and pine savannas. In Brunswick County there are several

near an escarpment possibly associated with a former beach front. One DWQ study site in

Brunswick County is an apparent lime sinkhole, another is a pine savannah.

(Tiner, Ralph W., 2003, Geographically Isolated Wetlands of the United States, Wetlands, vol. 23

no. 3, September, 2003, pp 494-516)

Bladen County, NC5 Miles

##

##

#

#

10 Miles

5 Miles

##

10 Miles

Brunswick County, NC

Study site

Study Locations

Legend

cntysgen

nccb83

ncSB83

100 Miles

100 Miles

NC Counties

SC Counties

Study area

10 Miles

Horry County, SC

10 Miles

7.5 MilesMarion County, SC

10 Miles