Data update: 10 years of Monitoring of Riparian Water Tables and Groundwater Chemistry
I. Natural Channel.
Image: Peter Groffman
II. Channel with incision due to increased runoff.
Image: Peter Groffman
Channel incision and reduced infiltration in uplands leads to lower water tables in the riparian zone which results in a change from wetland to upland soils and vegetation, and less filtering of upland-derived nitrate.
Check out our new updated data set on riparian water tables and groundwater chemistry, just posted HERE.
One of the most obvious effects of urbanization is the development of "urban stream syndrome" which is characterized by lower riparian water tables, drier riparian soils and loss of the riparian nitrogen removal function. In BES, long-term monitoring of riparian water tables and groundwater chemistry began in 2000 along four first or second order steams in and around the Gwynns Falls watershed in Baltimore City and County, MD. One site (Oregon) is in the completely forested Pond Branch catchment that serves as a "reference" study area for the Baltimore LTER (BES).
Urbanization leads to "flashier" storm flows which incise stream channels.
Image: Peter Groffman
Two sites (Glyndon, Gwynbrook) are in suburban areas of the watershed; one just upstream from the Glyndon BES long-term stream monitoring site in the headwaters of the Gwynns Falls, and one along a tributary that enters the Gwynns Falls just above the Gwynnbrook BES long-term stream monitoring site farther downstream. The final, urban site (Cahill) is along a tributary to the Gwynns Falls in Leakin Park in the urban core of the watershed. Data confirm that urbanization leads to a lowering of riparian water table and dramatic increases in nitrate, ammonium and phosphate levels in groundwater.
