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Development of Land Use Change Indicators to Support Watershed Based Restoration of Shellfish Resources Impacted by Fecal Coliform Contamination
Principal Investigators:
Nancy White
Michael Holmes
Dr. Leon Danielson

Dates:
1999-2000

Jumping Run Creek in North Carolina is the focus of a multi-disciplinary, multi-agency, watershed - based project that combines in-column water quality data, stormwater monitoring, stream flow measurements, with watershed assessment techniques, and community involvement to investigate causes of and solutions to reduce bacterial loading to shellfish beds. Field data indicate that stormwater flows are the primary transport vector; however, total "impervious surface" area in the water shed, a popular indicator of stormwater threats to water quality, is lass that 5%. This is well below the threshold of 12% -25% cited as the level which cause water quality degradation. Very little is understood with regards to the effects of land use change and bacterial loading. This effort reports on approach to measure change to land cover and relate it to bacterial loading rates.

areal photo showing changes made
the watershed in 1967

1979
1988
1994

Current parcel data was overlain onto scanned images of aerial photos of the watershed ranging from 1967 to 1994. Classification ranks were assigned to each parcel indicating the degree of land use / cover change for three categories -- clearing, ditching, and impervious surface area. These data were organized in a GIS database to facilitate spatial as well as temporal analysis. Using correlation and regression techniques, the variables were analyzed against thirty years of bacterial data.

Increased ditching in the watershed was positively correlated and statistically significant with increased bacterial loading. Imperviousness and cleared areas were not good indicators of bacterial densities. These results imply that time of concentration of rainfall in the watershed is an important factor in delivery of viable bacterial loads to shellfish resources in the sound.

GIS Map of parcels within the Jumping Run Creek watershed

Classification ranks were assigned to each parcel indicating the degree of land use/ cover change for three categories- clearing, ditching, and impervious surface area.