Effects of Urbanization on Stream-Riparian Zone Connection along Low Order Coastal Plain Streams of North Carolina

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Jeremy J. Robbins (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Headwater stream reaches , vital areas of exchange between upland and aquatic systems , are commonly affected by stream burial because they constitute a large fraction of total stream length and are more economically feasible to bury than higher order streams. In the U.S. , much of the work concerning stream burial has occurred in large cities (e.g. Baltimore , Detroit) , but this has been widely overlooked in smaller municipalities , particularly those located within the Atlantic Coastal Plain. The objectives of this study were to determine how urbanization affects drainage density (via stream network alterations such as burial and channelization) and influences the adjacent riparian vegetation and instream organic carbon retention in low-order Coastal Plain streams. For the purpose of this study percent total impervious area (%TIA) was used as a proxy for urbanization. It was hypothesized that urbanized watersheds (>20% TIA) would have a higher piped (‰¥ 15 in. or ‰¥ 38 cm diameter) drainage density than suburban and rural watersheds (<20% TIA). It was also hypothesized that watersheds with >20% TIA would depict stream-adjacent riparian buffer degradation and reductions in instream organic matter concentrations. Seven watersheds (1.0 km² to 3.3 km²) were chosen to portray a range of urbanization influences on receiving streams across an urban land-use gradient of 6.9% to 65.6% TIA. For each watershed , nested sampling (stream sediment and water quality) was performed at upstream , midstream , and downstream sites. In-situ evaluations of buffer integrity and stream assessment were performed at the same sites. Results indicated that piped drainage density and %TIA were strongly correlated (R=0.99) across each full watershed and all sub-watersheds (R=0.86). Results also indicated that streamside riparian areas with <20% TIA were relatively unaltered while >20% TIA ranged from somewhat altered to severely altered. Results of the instream organic matter analysis depicted significant relationships with non-purgeable organic carbon (p<0.05) and the non-purgeable organic carbon to total dissolved nitrogen ratio (p<0.05) having higher values at <20% TIA than those with >20% TIA. These findings confirm that as watershed impervious area increases drainage networks are transformed in order to manage excess stormwater runoff. Furthermore , increases in watershed impervious area have the potential to degrade the adjacent riparian buffer and reduce instream organic matter.

Additional Information

Publication

Thesis

Language: English

Date: 2017

Keywords

Stream Burial

Subjects

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