Date of Graduation

Spring 5-2012

Level of Access

Restricted: Campus/Bates Community Only Access

Degree Name

Bachelor of Science

Department or Program

Geology

Number of Pages

120

Abstract

The “grid ditching” of salt marshes is a 200 year old practice of marsh management that results in an effective drainage of the marsh and overall loss of pool habitat on the marsh surface. Recent restoration projects designed to remediate the effects of grid ditching on Sprague Marsh, located in Phippsburg, Maine, were initiated by the United States Fish and Wildlife Service in 2002, where eleven ditchplugs were installed in the southern end of the marsh. The focus of this study is to monitor and compare the hydrogeology in natural systems versus ditchplugged systems to determine if the restoration is adversely affecting natural processes in the marsh. Fifteen monitoring wells were installed in the southeastern section of the marsh, six in the northern alcove (control) and nine in the southern alcove (ditchplugged), to enable monitoring of water level, conductivity and temperature over several days. Land cover information, soil salinities, monitoring well stratigraphy, and slug test information was also gathered to aid in evaluating the existing hydrologic conditions. Results from the southern alcove indicate higher water table levels behind the ditchplug. Land cover information supports this finding by indicating increased low marsh environments, likely caused by the higher water table. The well monitoring experiment and analysis in ArcGIS indicate altered hydrologic flow due to the installation of the ditchplug towards observed portions of floating peat. The NA shows larger amounts of high marsh vegetation coverage due to lower inundation times and soil salinities. The well monitoring experiment and analysis in ArcGIS potenially show higher influxes of freshwater from the margins of the marsh.

Components of Thesis

1 pdf file

5 Microsoft Excel Files with data

Restricted

Available to Bates community via local IP address or Bates login.

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