GROUNDWATER FLOW PATTERNS AND SALT MARSH VEGETATION: BASELINE DATA ESTABLISHED BY A NEW HYDROLOGIC NETWORK IN A MID-ATLANTIC SALT MARSH IN GREENBACKVILLE, VIRGINIA

The coastal salt marshes of Greenbackville, Virginia have been altered by ditching, dredging, and draining. A section of these marshes has been additionally isolated by a road bed, a landfill, and berms created during historical oyster processing. Together, these structures almost entirely cut off free-flowing interactions with Chincoteague Bay waters with its additional beneficial sediment input. As sea level continues to rise in the area, there is concern about the restricted-flow portion of the marsh. In Summer 2014, we established a network of wells to monitor groundwater levels and salinity in the marsh in order to assess groundwater flow patterns in the marsh. Three observation wells were installed along three edges of the marsh, adding to the previously established system of ICON wells near the marsh transect. Temperature, water level, and conductivity are continuously monitored by sondes deployed in three of our wells. Six additional shallow wells enable us to collect water level measurements incrementally and, along with seven nests of shallow and deep piezometers, assess variations in the direction of groundwater flow over time. Water level and salinity profile data collected nearly daily over the summer will permit us to relate variations in groundwater flow direction to both precipitation events and tidal cycles. This network will enable us to monitor groundwater through the marsh and link any changes to outside climatological drivers.