Influence of groundwater flows on wetland restoration project at juniper bay
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Influence of Groundwater flows on Wetland Restoration Project at Juniper Bay. SSC 570 - Wetland Soils Term Paper Presentation. Swamy Pati Bio. & Ag. Engineering Dept., NCSU. Outline. Introduction Carolina Bays Wetland Restoration Requirements Project Objectives Methodology. Introduction.

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Influence of groundwater flows on wetland restoration project at juniper bay l.jpg

Influence of Groundwater flows on Wetland Restoration Project at Juniper Bay

SSC 570 - Wetland Soils

Term Paper Presentation

Swamy Pati

Bio. & Ag. Engineering Dept., NCSU


Outline l.jpg
Outline Project at Juniper Bay

  • Introduction

  • Carolina Bays

  • Wetland Restoration Requirements

  • Project Objectives

  • Methodology


Introduction l.jpg
Introduction Project at Juniper Bay

  • Research project – Assessment of Groundwater flows at Juniper Bay and their impacts on the surrounding area.

  • This project is a supplement to the wetland restoration project underway at Juniper Bay.

  • Project mainly focuses on the influence of the subsurface flows on wetland restoration.

  • Juniper Bay is one of the Carolina Bays, which are spread throughout the Southeastern Coastal plain of US.


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Literature review – Origin of Carolina Bays Project at Juniper Bay

  • Carolina Bays are small orientated depressions, elliptical to ovate in shape, that the south-eastern coastal plain of the united states in incredible density and range.

  • Extend from the Delmarva Peninsula in north to the Okefenokee swamp in Northern Florida.


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Arial Photograph Project at Juniper Bay


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Origin of Carolina Bays Project at Juniper Bay

  • D.W. Johnson, 1936 – shape and orientation, as well as presence of sandy rims are attributed to wind and wave action and depressions are attributed to the artesian process.

  • W.F. Prouty, 1952 – comet or asteroidal body entering the earth atmosphere at an oblique angle from a relatively northwesterly direction.

  • Bruce G. Thom, 1970 – Humate allows for a perched water table near the surface that would eventually evolve into shallow, wet depressions, orientated later by wind and wave action.


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Origin of Carolina Bays Project at Juniper Bay

  • J. Ronald Eyton & Judith I. Parkhurst, 1975 – considered the theory stated by Prouty, 1952 and then they stated finally that comets are the cause for the creation of Carolina Bays.

  • Raymond T. Kaczorowski, 1977 – ruled out the extraterrestrial theory as a cause for Bay formation and supported Thom’s water table perching theory. He suggested that the only requirement for Bay existence is poor drainage leading to ponding mechanisms.

  • Reference: http://bss.sfsu.edu/jdavis/geog810/1999/black.html


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Hydrology of Carolina Bays Project at Juniper Bay

  • The hydrology of Carolina Bays is influenced by subsurface flows inputs and fine textured soil or parent material layers that restrict the downward movement of stored water in the Bay.

  • Studies on the complex hydrology of Carolina Bays have shown complex subsurface interaction with the surrounding area

  • Local depressional hydrology superimposed on the regional subsurface hydraulic gradients of the landscape in which the bay occurred.


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Wetland restoration Requirements Project at Juniper Bay

  • Wetland restoration projects needs assessment of the site in all factors to meet the restoration goals set by the US Army Corps of Engineers.

  • Wetlands hydrology, hydric soils, and plant community similar to the reference ecosystem be restored.

  • Site assessment, identification of potential functions, methodologies to restore wetland functions, and effective assessment of progress of functional restoration.


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Hydrologic aspects of Wetland Restoration Project at Juniper Bay

  • Ditching and pumping in the surrounding area of the site

  • Regional subsurface hydraulic gradients

  • Filling the ditches is not suffice

  • Regional hydrology must be assessed and restoration methods must account for restoration of historical regional surface and subsurface hydraulic gradients.


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Juniper Bay Project at Juniper Bay


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Groundwater flows at Juniper Bay Project at Juniper Bay

  • Lateral Groundwater Flows

  • Preliminary work suggests non-negligible gradients across JB boundary

  • Core data suggest an effective bottom to the surficial system – Black Creek Confining Unit

  • Current well/piezometer network insufficient to assess lateral flows


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Stratigraphy Project at Juniper Bay


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Importance of Perimeter Ditch Project at Juniper Bay

  • Lateral boundary of the project is the perimeter ditch.

  • It influences the flows in the surficial aquifer and prevents the flows between interior and exterior of the bay.

  • It can effectively drain 100 feet to either side.

  • Influence of the perimeter ditch through the partially confined sand layers underlying the surficial aquifer is one of the main trusts of the project.


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Objectives Project at Juniper Bay

  • Characterize the subsurface flows at four locations on the perimeter

  • Interaction of the perimeter ditch

  • Model the subsurface flows

  • Develop the management recommendations.


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Characterize the subsurface flows Project at Juniper Bay

  • Four locations are selected around the perimeter of the project site.

  • Coring work was started in these locations.

  • Coring is being done at 5 points at each transect.

  • These are the same points at which nests of piezometers will be installed.


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North-facing view of the Juniper Bay Project at Juniper Bay


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Locations of Piezometer Transects Project at Juniper Bay


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Transect of Piezometer Nests Project at Juniper Bay


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NW - Transect Project at Juniper Bay


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SE - Transect Project at Juniper Bay


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SW - Transect Project at Juniper Bay


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NE - Transect Project at Juniper Bay


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Characterize the subsurface flows Project at Juniper Bay

  • With the cores collected at different locations saturated hydraulic conductivity tests are conducted and values are estimated.

  • Then flows crossing site boundaries will be calculated.


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Ksat table Project at Juniper Bay


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Piezometers Project at Juniper Bay

  • Piezometers are installed at these locations at all significant sand layer at each point on the transect.

  • Hydraulic heads will be monitored in the piezometers and perimeter ditch.

  • Instrumentation is installed with all the piezometers to monitoring the water levels.

  • Hydraulic gradients, Hydraulic conductivities, lateral and vertical fluxes will be estimated


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Future Work - Additional Field Work Project at Juniper Bay

  • Perimeter cores (8-12) for stratigraphic data

  • Ground-penetrating radar surveys


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Additional Coring Project at Juniper Bay


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Role of the Perimeter Ditch Project at Juniper Bay

  • How deeply does the perimeter ditch influence subsurface flows?

  • Could/should it be preserved to control boundary flows? What management scheme?

  • Elimination of the perimeter ditch could increase wetland area by 30-100 acres.


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Groundwater Modeling Project at Juniper Bay

  • There are various different kinds of modeling software available to model groundwater.

  • Some of them are CFEST, MIGRATE, DYNFLOW, MODFLOW, etc.

  • Except MODFLOW most of the other groundwater flow models are used to simulate the solute or chemical transport phenomena.

  • In this project we are mainly dealing with the hydraulic aspects of the groundwater flow, MODFLOW will be appropriate to use.


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MODFLOW Project at Juniper Bay

  • Input parameters: Aquifer parameters, hydraulic parameters, dimensionality, initial conditions boundary conditions.

  • Some of the input parameters will be estimated from the field data.


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MODFLOW Project at Juniper Bay

  • MODFLOW simulates hydraulic head and velocity field distribution and they solve the groundwater flow equation.

  • This model can handle multiple layer porous media, with either confined, unconfined or semiconfined. Heterogeneous, anisotropic or compressible porous media can also be modelled.

  • Finite difference solution technique is used in this model.


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MODFLOW Project at Juniper Bay


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MODFLOW Project at Juniper Bay

  • Number of layers and the input parameters change depending on the scenario the model is run for.


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Modeling Project at Juniper Bay

  • Using the model we predict the flows in the surficial aquifer for the entire site

  • Model will be run for different management scenarios – w/ & w/o the perimeter ditch

  • Predict the impacts of the conversion on the water table levels in adjacent properties


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THANK YOU Project at Juniper Bay

Questions?