Document Type
Thesis
Abstract
In recent studies of urban riparian zones, the hydrology of the area has been altered by urbanization and as streams were incised the water table was significantly lowered, causing hydraulic drought. In an area of James City County, Virginia, there is a riparian zone that is protected from the effects of urbanization because it is in a Resource Protection Area as described in the Chesapeake Bay Protection Ordinance. A knickpoint within this stream has been rapidly migrating upstream causing the stream to deeply incise into its floodplain, thus is it likely altering the water table elevation and recharge capabilities of the floodplain. Without recharging onto the floodplain, this ecosystem may become a source, not a sink, for nutrients and pollutants that should be naturally cycled through the floodplain. This research compares the water table depth and its depth below the floodplain upstream and downstream of this knickpoint, as well as compares nutrients in the stream and floodplain groundwater in order to determine trends in these two separate environments. This is the first documented study site comparing a wetland environment to an incised floodplain in the same stream. Because the two environments are within the same watershed, the effects of incision can be adequately documented, because rainfall, urbanization, and many other variables can be held constant for both the un-incised upstream environment and the incised downstream environment. The results of this study show that the water table elevation drops in area of the floodplain adjacent to the stream. Because of this, flow pathways also change from parallelling the stream upstream of the knickpoint and flowing perpendicular to the stream where the stream is incised. Geochemistry results show that the upstream environment is likely a reducing environment and downstream is an oxidizing environment. The effects of urbanization in this watershed have been found to be strongly affecting this ecosystem’s water table elevation, and stream and groundwater chemistry.
Date Awarded
2007
Department
Geology
Advisor 1
Gregory S. Hancock
Recommended Citation
Robertson, Laura R., "Impacts of Channel Incision on Water Table Elevation and Chemistry" Upper Chisel Run, James City County, VA" (2007). Geology Senior Theses. William & Mary. Paper 183.
https://scholarworks.wm.edu/geologyseniors/183
