The Effect of Land Use Change on Nitrogen Load into the Buzzards Bay, MA Watershed

Shanna C. Williamson, Woods Hole Oceanographic Institution, swilliamson@whoi.edu (Presenter)
Jennie E. Rheuban, Woods Hole Oceanographic Institution, jrheuban@whoi.edu
David M. Glover, Woods Hole Oceanographic Institution, dglover@whoi.edu
Joseph E. Costa, Buzzards Bay National Estuary Program, joe.costa at state.ma.us
Scott Doney, Woods Hole Oceanographic Institution, sdoney@whoi.edu

Land use change within coastal watersheds may alter nutrient loads into receiving waters, which can increase primary productivity, induce eutrophic conditions, and degrade water quality. As a result, monitoring changes to land use and nitrogen load is essential for water quality assessment. Here, we simultaneously assess changes to land use within the Buzzards Bay, MA watershed, and the impact of such changes on nitrogen load over several decades. We utilize a previously verified nitrogen load model (NLM) requiring land use, atmospherically deposited nitrogen, and wastewater disposal data to determine the effects of changing land use mosaics on nitrogen input into Buzzards Bay. Land cover classifications derived from the NOAA Coastal Change Analysis Program (C-CAP) and Massachusetts land use (MassGIS) databases allowed us to develop a time series of land use mosaics from 1985, 1996, 1999, 2001, 2006, and 2010. A preliminary investigation of changes to land use in the Buzzards Bay watershed reveal that about half of the embayments had a statistically significant change to land use mosaics over the past thirty years which influenced nitrogen load. Two major nitrogen sources in the NLM include human wastewater and runoff from impervious surfaces suggesting that the embayments with increases in urbanized areas and populations will have increases in nitrogen load. Declines in atmospherically deposited nitrogen suggest that embayments with no change in land mosaics will have declining nitrogen loads. This analysis will inform future development of the Buzzards Bay watershed by highlighting embayments susceptible to declines in water quality from changing land use and the resulting nitrogen load.

Presentation Type:  Poster

Session:  Theme 4: Human influence on global ecosystems   (Mon 4:30 PM)

Associated Project(s): 

• Related Activity: Related Activity or Previously Funded CC&E Activity not listed ...details

Poster Location ID: 94