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Research: Water Quality

Water quality is defined as the biological, chemical, and physical conditions of a water body. It is a measure of a water body's ability to support beneficial uses (Virginia Department of Environmental Quality).  Water quality is affected by physical and biotic elements.  For example, suspended silts and clays may decrease water clarity and adversely impact submerged aquatic vegetation.  However, these suspended sediments are important inputs for sustaining wetlands.

Hypoxia Studies: Development of DO TMDL for Onancock Creek (2005)

Onancock CreekLow dissolved oxygen (DO) is often observed in eutrophic waters that receive excessive nutrients and organic matter.  DO levels below state water quality standards require the development of a total maximum daily load (TMDL) to determine the reductions needed to meet the water quality standard. The North Branch of Onancock Creek, located on the Eastern Shore of the Chesapeake Bay, is impaired for DO. This project involved the development of a 3-D hydrodynamic and water quality model to determine various scenarios for source allocations between point and nonpoint sources.

Link to Report


Hypoxia in a Coastal Embayment of the Chesapeake Bay: A Model Diagnostic Study of Oxygen Dynamics (2008)

hypoxiaIn this study, the hypoxia in Onancock Creek was examined by the analysis of high-frequency dissolved oxygen (DO) measurements and a simplified DO-algae model, developed to simulate DO distribution during the summer period.  The model was then used to perform diagnostic studies of the mechanisms controlling DO dynamics in the North Branch of Onancock.  The results show that the modeling approach used in this study enables important physical and biological factors of DO dynamics in the creek to be captured and it permits diagnostic studies of DO processes. High biomass of macroalgae interacting with low light and high temperature are the dominant factors explaining low DO in North Branch of Onancock Creek in July, 2004.

Link to Paper



Rappahannock County Riparian Buffer Study (2006)

riparian shorelineRiparian buffers are important zones for maintaining water quality and providing critical habitat. Rappahannock County has a rural landscape that presents the opportunity to record baseline conditions of riparian buffers.  This study involved analyzing a small drainage area in the Upper Thornton River watershed to offer guidance on targeting riparian buffer restoration.  Methods included using aerial imagery and GIS to delineate land uses and buffer cover in 100 foot buffers around streams.  Results indicate that in the study area 51% of the riparian lands potentially need some restoration and several recommendations for riparian buffer restoration were made in the final report. This study has implications for water quality issues as well as sediment inputs and stream bank erosion.

Link to Report