Floodplain Wetland and Channel Floodplain Wetland and Channel Biogeochemical Relationships Biogeochemical Relationships following Dam Removal on a following Dam Removal on a

Coastal Plain RiverCoastal Plain River

Adam RiggsbeeAdam Riggsbee11, Robert G. Wetzel, Robert G. Wetzel11, , Martin W. DoyleMartin W. Doyle22 and Jason P. Julian and Jason P. Julian22

1 1 Department of Environmental Sciences and Department of Environmental Sciences and Engineering at UNC-Chapel HillEngineering at UNC-Chapel Hill

22 Department of Geography at UNC-Chapel Hill Department of Geography at UNC-Chapel Hill

Today’s TalkToday’s Talk

• The dam removal The dam removal begins…begins…– Fresh Data (4-28-05)Fresh Data (4-28-05)– Dam dewatering Dam dewatering

releases stored releases stored wetland surface and wetland surface and ground waters into the ground waters into the adjacent channeladjacent channel

• Biogeochemical Biogeochemical impactsimpacts

– DOCDOC– NONO33, NH, NH44

– POPO44

Little River BackgroundLittle River Background

• 44thth order order • Edge of piedmont and Edge of piedmont and

coastal plain coastal plain • Neuse River Basin Neuse River Basin • Matrix supported Matrix supported

sand/gravel sand/gravel • Floodplain wetlands are Floodplain wetlands are

permanently inundated permanently inundated bottomland hardwood bottomland hardwood forests (impounded)forests (impounded)

• ~ 8km impoundment~ 8km impoundment

Little River, NCLittle River, NC

DamDamFLOW

Impoundment DewateringImpoundment Dewatering

April 25, 2005

Impoundment DewateringImpoundment Dewatering

April 28, 2005

June 06, 2005

Floodplain SuccessionFloodplain Succession

July 13, 2005

Little River, NCLittle River, NC

DamDam

FLOW

ISCO 1

ISCO 2

Dewatering HydrologyDewatering Hydrology

• Event occurred near Event occurred near baseflow (1.87 mbaseflow (1.87 m33/s)/s)

• QQpeakpeak = 3.20 m = 3.20 m33/s/s

• DurationDuration– 13 h13 h

• Dam Team sampled Dam Team sampled for 8 hfor 8 h– 6 h during event6 h during event

Preliminary ConclusionsPreliminary Conclusions

• Minimal loading Minimal loading

• Short duration Short duration

• TSS/Nutrient contributions negligible TSS/Nutrient contributions negligible relative to other dam removal studiesrelative to other dam removal studies– Doyle, et al. 2003Doyle, et al. 2003

Little River, NCLittle River, NC

DamDam

FLOW

ISCO 1

ISCO 2

Wetland Surface HWetland Surface H22O DewateringO Dewatering

• Little impact on channel biogeochemistryLittle impact on channel biogeochemistry

• TSS contributions rapidly attenuatedTSS contributions rapidly attenuated

• What about wetland groundwater What about wetland groundwater drainage?drainage?

Ongoing Dewatering ResearchOngoing Dewatering Research

Ongoing ResearchOngoing Research

• Floodplain wetland Floodplain wetland plant treatmentsplant treatments– ColonizedColonized– UncolonizedUncolonized

• Plant biomassPlant biomass• Fungal biomassFungal biomass• Bacterial productivityBacterial productivity• Interstitial [N, P, C]Interstitial [N, P, C]

Ongoing ResearchOngoing Research

• Greenhouse Greenhouse mesocosmsmesocosms– Nutrient attenuation Nutrient attenuation

during low velocity during low velocity flood eventsflood events

• Independent variableIndependent variable– Plant biomassPlant biomass

– Nutrient source/sinkNutrient source/sink

Acknowledgements

• Robert G. Wetzel

• The Dam Team (4-28-05)

• The Wundergrads

• US Fish and Wildlife Service

• Restoration Systems, LLC.