Submitted to: Chesapeake Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 3, 1994
Publication Date: N/A
Interpretive Summary: Land owners in the Chesapeake Bay watershed are encouraged to preserve or restore streamside (riparian) ecosystems as a way to improve water quality. One way healthy riparian ecosystems may improve water quality is by keeping farm chemicals out of streams. However, we do not know enough about what types of ecosystem works best, where they work best or how much good they will do. Setting up research sites to answer these questions is costly an time consuming and many sites do not have the necessary below ground features. We present a procedure to quickly explore the below ground characteristics of a site to decide if it is suitable to study pollution control in riparian ecosystems. A fast and relatively inexpensive procedure makes it more likely that unsuitable sites will be rejected before so much has been invested in a site that the questions are changed to match the site, rather than the site changed to answer the intended questions. The group of proposed tests should expose below ground complexities at a site that must be avoided, or addressed in a data collection program. The below ground, water flow characteristics combined with plant and soil biology information can then be used to assess the likelihood that riparian ecosystems will buffer streams from pollutants in various parts of the Chesapeake Bay watershed.
Technical Abstract: In the humid East, groundwater passes through riparian ecosystems before discharging into streams. Characteristics of riparian ecosystems control the cycling and sequestering of NPS pollutants within the near-stream environment. The degree to which these processes attenuate the concentration of groundwater contaminants depends on the extent of the riparian zone and flow patterns through it. If much agricultural drainage leaks to regional groundwater or enters the stream through the channel bottom, the possibility for groundwater renovation within the riparian zone decreases. Geophysical and hydrologic investigations help to define flow paths from upland sites to the stream. Seismic surveys reveal the depth to and configuration of bedrock interfaces, plus major discontinuities that might affect flow patterns. Slug tests give aquifer permeability and piezometric head distributions yield flow directions. Together this information can be used to calculate the degree of interaction between discharging groundwater and riparian ecosystems. Seismic surveys, slug tests and piezometric head are used to assess flow patterns within riparian zone sites in the Valley and Ridge physiographic province of Pennsylvania. Flow paths are modeled for the range of measured properties and inferences drawn concerning the potential for groundwater renovation within the riparian zone.