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Floodplain Wetland and Channel Biogeochemical Relationships following Dam Removal on a Coastal Plain River. Adam Riggsbee 1 , Robert G. Wetzel 1 , Martin W. Doyle 2 and Jason P. Julian 2 1 Department of Environmental Sciences and Engineering at UNC-Chapel Hill
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Floodplain Wetland and Channel Biogeochemical Relationships following Dam Removal on a Coastal Plain River Adam Riggsbee1, Robert G. Wetzel1, Martin W. Doyle2 and Jason P. Julian2 1 Department of Environmental Sciences and Engineering at UNC-Chapel Hill 2 Department of Geography at UNC-Chapel Hill
Today’s Talk • The dam removal begins… • Fresh Data (4-28-05) • Dam dewatering releases stored wetland surface and ground waters into the adjacent channel • Biogeochemical impacts • DOC • NO3, NH4 • PO4
Little River Background • 4th order • Edge of piedmont and coastal plain • Neuse River Basin • Matrix supported sand/gravel • Floodplain wetlands are permanently inundated bottomland hardwood forests (impounded) • ~ 8km impoundment
Dam Little River, NC FLOW
April 25, 2005 April 28, 2005 Impoundment Dewatering
June 06, 2005 Floodplain Succession July 13, 2005
ISCO 1 Dam ISCO 2 Little River, NC FLOW
Dewatering Hydrology • Event occurred near baseflow (1.87 m3/s) • Qpeak = 3.20 m3/s • Duration • 13 h • Dam Team sampled for 8 h • 6 h during event
Preliminary Conclusions • Minimal loading • Short duration • TSS/Nutrient contributions negligible relative to other dam removal studies • Doyle, et al. 2003
ISCO 1 Dam ISCO 2 Little River, NC FLOW
Wetland Surface H2O Dewatering • Little impact on channel biogeochemistry • TSS contributions rapidly attenuated • What about wetland groundwater drainage?
Ongoing Research • Floodplain wetland plant treatments • Colonized • Uncolonized • Plant biomass • Fungal biomass • Bacterial productivity • Interstitial [N, P, C]
Ongoing Research • Greenhouse mesocosms • Nutrient attenuation during low velocity flood events • Independent variable • Plant biomass • Nutrient source/sink
Acknowledgements • Robert G. Wetzel • The Dam Team (4-28-05) • The Wundergrads • US Fish and Wildlife Service • Restoration Systems, LLC.