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1. Santee Experimental Forest
Wetland Restoration
Cecilia Eargle, Ashton Guest, Ramona Kahler, Aaron Reeser, and Madison Socha
Clemson, SC
December 3, 2019

2. Outline
● Introduction
○ Background
○ Rationale
○ Objectives
○ Approaches
● Literature Review
● Materials and Methods
● Results
○ Flooding
○ Erosion
● Take Home Message
● Acknowledgements

3. Introduction

4. Background
● USDA issued project proposal
● Francis Marion National Forest
● 18th and 19th century irrigation
canals and watering cattle
● 20th and 21st century timber and
ecological research

5. Our Watershed
Monitored Watersheds
used for Reference

7. Rationale
● Degraded hydrology
○ Channelization drained watershed
○ Bottomland hardwood forest
○ Hardwood flat
● Loss of natural habitat
○ Disrupted ecosystem
○ Destroyed habitat of native species

8. Objectives
The objectives of this project are to
(1) develop engineering systems for soil and water management to
restore wetlands of the Francis Marion National Forest,
(2) design hydraulic structures for open channel flow, and
(3) evaluate designs based on their effectiveness, cost, and
environmental impacts in order to recommend a final design that
meets the standards for the best management practices outlined
by the US Army Corps of Engineers

9. Approaches
Task 1. Conduct a preliminary site survey in order to determine the project
boundaries and take measurements of the channel
Task 2. Collect and analyze soil samples for soil physical and chemical
characterizations
Task 3. Perform hydraulic and hydrologic measurements for surface and
groundwater characterizations
Task 4. Determine U.S. Army Corps of Engineers proposed action
guidelines
Task 5. Model hydrology of the area to identify the best course of action for
channels and wetlands
Task 6. Evaluate cost analysis and environmental impacts for proposed
solutions

10. Hydric
Soil
Water
Table
Wetland
Vegetation
Habitat
Alteration
Hydrology
Sediment
Transport
Capstone
Design

11. Literature Review

12. Wetland Restoration
Wetland restoration involves returning one or more of these three
characteristics to a degraded site:
● Hydrology
● Hydric soil
● Wetland vegetation
Restoration project sites can vary due to:
● Ditched, tiled and leveed areas for agricultural purposes
● Degradation from excessive logging
● Uncontrolled cattle grazing
● Unrestricted off-road vehicle use

13. Bottom Contouring
● Cut and fill method
● Modified by removal (cut) or addition (fill)
● Surface sediment
● Sediment fill can raise the water table in
flat wetlands that have:
○ Channels
○ Ditches
○ Streams
● Equal cut and fill
○ No export or import of
sediment

14. Cut and Fill Case Study
● Location: Kissimmee River
○ Central Florida
● Problem: River became
compartmentalized
○ Altered hydrology of surrounding
areas
● Solution: Cut and fill
○ Increased the water table
○ Restored wetland habitats for
native species

15. Water Control Structures
● Bring water into the wetland, and maintain a desired water level
● Inlet and Outlet Structures
○ Water will arrive to the wetland by gravity from surface streams
○ Outlet structures are designed to be the primary control on water level and
maintain flow distribution
● Ease of operation and ability to set the desired water level.
○ Outlets devices should have enough capacity to accommodate for peak storm
events within the design range

16. Weirs
● A structure built across a river or stream and
provides a constriction that regulates flow and raises
the level of water upstream
● Can become blocked by ice or floating debris
● In small wetlands, flashboards or adjustable weir
gates are common
○ Flashboard structures are made from stacked
dimensioned lumber and water level is adjusted
through the addition or removal of logs

17. Low Water Crossings
● Stable roadway used to cross streams
● Allows for the natural passage of water and sediment over a road with little to no
maintenance
● Constructed of crushed aggregate, concrete, concrete planks and/or brick tiles
● Vented or Unvented

18. Vented Low Water Crossing Case Study
● Location: Indian Creek
○ North Carolina
● Problem: Recreational fishing and high
flow rate
● Solution: Vented Low Water Crossing
○ Easy access for fish
○ Protects crossing from damage
Vents

19. Unvented Low Water Crossing Case Study
● Location: Cienega Creek
○ Arizona
● Problem: Need for natural passage of flow
because of seasonal flooding
● Solution: Unvented Low Water Crossing
○ Traffic passes with or without seasonal
flooding

20. Berms
● Earthen embankments constructed to
contain water
● Require maintenance
● Sometimes created through scrapes
● Conjunction with water control structures

21. Ditch Plugs
● The filling of a section of a drainage path
with an earthen wall
● Slow flow through a drainage path and
increasing water retention
● Emergency spillways can protect the
structure from damage. An orifice may be
used to allow flow through the ditch plug

22. Ditch Plugs Case Study
● Location: Seney, MI
● Problem: Need to restore land back to its
original environment, a wetland
○ 2002 USDA began restoration
project
● Solution: Ditch Plugs
○ 9 Plugs
○ Colonization of wetland species
and rise of water table
Ditch Plug

23. Tile Breaks
● Removal or breaking of an underground clay or
perforated plastic drain tile
● Buried at a depth of two to six feet, drain tile is often
removed by a contractor
● Tile breaks restore wetland hydrology, vegetation and
wildlife back to its original ecosystem

24. Tile Breaks Case Study
● Location: Ozaukee County
○ Wisconsin
● Problem: Drain tiles dried out the soil
○ Agricultural fields had been made out of
wetlands
○ 1989 USDA proposed wetland restoration
● Solution: Tile Breaks
○ water table levels began to rise and wetland
vegetation was making a come back

25. Venturi Flumes
● Channel that transports water through the
use of gravity
● A constriction in a standard flume forces the
flow upstream of the constriction to be
subcritical, and downstream to become
supercritical
● Flumes allow unimpaired passage through
the structure, however, do not form a stilling
basin upstream
● Examples of constricted flumes are the H-
Type and the Parshall flume

26. Vegetation Establishment
● Restored wetlands place considerable
emphasis on vegetative diversity
● Competitive die-out continuously changes
plant communities
● Assisted Natural Selection
● Altering the water table, the top layer of the
zone of saturation, can have a impact on
the prosperity of certain plant species in an
area

27. Materials and Methods

28. Our Project Site
● Our site:
○ Hardwood Flat
○ A 1500 ft section of Nicholson
Creek Watershed, most of
which has been channelized
○ The watershed is approximately
500 ac
○ Surface elevations varying from
3.5 to 6.5 ft
○ Less than 1 % slope
Stream
restoration sites
---- Project site

29. Hardwood flat
dendrology
(6) Dwarf palmetto
Sabal minor
(7) Swamp chestnut oak
Quercus michauxii
Bottomland hardwood
forest dendrology
(1) American holly
Ilex opaca
(2) American beech
Fagus grandifolia
Dendrology found
in both
(3) Loblolly pine
Pinus taeda
(4) American sweetgum
Liquidambar styraciflua
(5) Red maple
Acer rubrum
(1) (2) (3) (4) (5) (6) (7)

30. Soil Conditions
● Hydric soil is soil that is permanently or temporarily
saturated with water. Soil can take years to reach hydric
conditions
● An indicator of hydric mineral soil is called gleying
○ Gleying is a lack of oxygen in soil which turns the
soil a blue or grey
● The sediment beneath the topsoil of this project area is
grey supporting that the watershed already contains
appropriate soil for wetland restoration to be viable
without the need for hydric soil conditions to develop or
the import of hydric soil

31. Climate Conditions
● This project site experiences 44-49 in of rainfall per year
● During the fall it experiences less than 2 in of rainfall per month
● In the summer the area experiences 6-8 in per month due to
intense hurricanes and thunderstorms
● These rainfall periods can cause inundation of the watershed
during this time of the year
● This gives us an adequate amount of water to raise the water table
with the proper wetland restoration technique

32. Topographic Surveying
● Digital Elevation Model (DEM)
map
○ 1 meter resolution
○ Provides specific topographic data
such as flood bank levels

33. Channel Survey
● Flood Bank Level
○ Channel dimensions
○ Total station
● Channel
○ Open channel cross-section found
with range finder
○ Control structure dimensions

34. Soil Collection and Analyses
● Soil was collected at several key points along and in
the channel using a manual auger
○ Soil analyses
○ Soil type
○ Soil physico-chemical properties

35. Groundwater Monitoring
● A well was installed in the channel to
monitor the water table height in 15 minute
intervals since implementation
● allows for a comparison with watershed 80
which has historical flow and climate data

36. Bottom Contouring
● Use the soil that is currently on
the channel banks to fill in the
bottom of the channel
● Large horizontal:vertical side
slope increases wetted
perimeter, decreasing flowrate

37. Culvert Removal
● Two culverts at intersection of main
channel and Tanner Road
● This site is a potential location for a low
water crossing
● Stormwater flow does not currently rise
to a high enough elevation to overflow
the road
● Removing this culvert reduces flow in
the drainage channel

38. ● Auto Computer Aided Design version 2018
○ Modeled channel dimensions to show cut and fill
■ Design equal cut and fill
○ Model a weir addition
○ Model the creation of a low water crossing
Modeling Channel Dimensions and Hydraulic
Structures with AutoCAD

39. Flow Modeling
● Hydrologic Engineering Center River
Analysis System (HEC-RAS)
● Inputs
○ geometry of site
○ Manning’s numbers (n)
○ Rainfall and Climate Data
○ Historic data, DHEC Stormwater
Management Handbook
○ Site specific rainfall and climate
data compiled by USDA FS

40. HEC-RAS Flow Model
● Uses the one-dimensional energy equation (1) to solve for flow
● Manning’s equation (2): used to find velocity
● Gives an output of flow area at each cross sectional area of the channel
(1)
(2)

41. Soil Modeling
Inputs:
● Geometry of the site
○ Same variables as those used in flooding calculations
● Quasi-Unsteady Flow of the channel
○ Flow of the channel over time
○ Temperature of the area during the simulation time
● Sediment
○ Create a bed gradation: state the composition of the soil as
percentiles of soil textures
○ Fall velocity- how the sediment types fall in the stream beds
○ Maximum depth

42. ● HEC-RAS uses the Exner continuity equation to state that the difference
between sediment entering and leaving an area must be either stored or
removed from storage
HEC-RAS Soil Model
Sediment entering - sediment leaving = change in storage in the control volume
(between cross-sections) (by erosion / deposition of sediment)
Active layer
porosity Transported
sediment load
Channel elevation

43. Results

44. Soil Data: Soil Texture
● Soil samples were collected along the channel and analyzed for their soil type
and grain size
○ The results showed the composition included an average of 71.88%
sand, 15.86% silt and 12.26% clay

45. Soil Data: Chemical Composition
● Further analysis identified the chemical qualities of the soil
○ Including and average pH of 5.97, average Buffer pH of 7.68, and key
nutrients in pounds per acre
○ These results provide a basis for analyzing what plant species are able to
thrive in the soil
Sample
ID
Soil pH Buffer
pH
P
lbs/A
K
lbs/A
Ca
lbs/A
Mg
lbs/A
Zn
lbs/A
Mn
lbs/A
Cu
lbs/A
B
lbs/A
Na
lbs/A
SS1 5.3 7.4 9 60 2038 172 1.4 25 0.2 0.8 21
SS2 6.4 7.95 61 27 1085 48 2.7 11 0.4 0.2 21
SSwell 6.2 7.70 458 78 3775 185 0.8 66 0.5 0.5 50

46. Rainfall and corresponding water table
● Records the groundwater table height with respect to the bottom of the
channel
● Shows the reaction of the water table from rainfall in 15 minute intervals since
implementation
● If the channel bed is raised, the water table change would also be monitored

47. About Water – Groundwater Data
●Need to have Groundwater data

48. Pre-Development Channel Dimensions

49. Pre-Development – Flooding Cross Sections
● HEC-RAS output flooding
channel
channel

50. Legend
Floodplain
Channel Banks
Water
Tanner Road
Pre-Development Flooding Conditions

51. Pre-Development – Flooding Data
Predevelopment Velocity
(ft/s)
Cross
sectional
area (ft2)
top width
(ft)
Average Upstream 0.33 11.24 73.17
Average downstream 0.43 10.75 66.02
Overall Average 0.41 10.86 67.51
Velocity
● A high water velocity could damage any
present water control structure
● Keeping the velocity low allows for structure to
withstand more intense flooding conditions
Cross Sectional Area
● This is the area of the cross sections that is
below water when running the simulation
● A higher cross sectional area means a greater
water depth
Top Width
● The top width is the width of the water’s
surface
● The wider the water's surface, the higher the
storage area for flooding

52. Pre-Development – Soil erosion conditions
● HEC-RAS soil transfer
simulations are able to show
soil build up across the
different reaches of a river
● The build up is most easily
identified when observing the
Profile plot which shows a
difference between the
channel bed and the build up
of soils

53. Post-Development – Channel Filling
● Channel in AutoCAD
Legend
Area To Be
Filled
Area To Be Cut

54. Channel Filling Flood Modeling
Predevelopment

55. Channel Filling Cross Section
Original Cross Section
Adjusted Cross Section

56. Channel Filling Analysis
With Channel Filling
Velocity
(ft/s)
Cross
Sectional
Area (ft2)
Top
Width
(ft)
Average Upstream 0.02 136.60 92.56
Average Downstream 0.38 10.99 64.38
Overall Average 0.31 37.16 70.25
Predevelopment
Velocity
(ft/s)
Cross
Sectional
Area (ft2)
Top
Width (ft)
Average Upstream 0.33 11.24 73.17
Average
Downstream
0.43 10.75 66.02
Overall Average 0.41 10.86 67.51

57. Channel Filling Cost Analysis
Component Name Price ($/unit) Quantity Cost ($)
Compacted
Sediment Fill
$5.75 per yd3 245 yd3 $1408.75
Hydraulic Excavator $117.15 per hour 40 hr $4,686.00
Heavy Equipment
Operators
$33.69 per hour 40 hr $1,347.60
Mobilization $919.24 per item 1 excavator $919.24
Total Cost $8,361.59

58. Weir Installment Flood Modeling
Predevelopment

59. Weir Installment Cross Section
Predevelopment Cross Section Post development Cross Section

60. Weir Installment Analysis
Weir Design
Velocity
(ft/s)
Cross
Sectional
Area (ft2)
Top Width
(ft)
Average
Upstream
0.0220 135.2 92.6
Average
Downstream
0.0663 113.8 102.0
Overall
Average
0.0571 118.2 100.1
Predevelopment
Velocity
(ft/s)
Cross
Sectional
Area (ft2)
Top
Width (ft)
Average Upstream 0.33 11.24 73.17
Average
Downstream
0.43 10.75 66.02
Overall Average 0.41 10.86 67.51

61. Weir Installment Cost Analysis
Component Name Price ($/unit) Quantity Cost ($)
Compacted Berm
Sediment
$5.75 per yd3 7 yd3 $40.25
Hydraulic Excavator $117.15 per hour 20 hr $2,343.00
Heavy Equipment
Operators
$33.69 per hour 20 hr $673.80
Concrete Weir $4.10 per bag 4 bags $16.40
Mobilization $525.28 per item 1 excavator $525.28
Total Cost $3,598.73

62. Culvert Removal Flood Modeling Data
Predevelopment

63. Culvert Removal Cross Sections
Predevelopment Cross Section Post development Cross Section

64. Culvert Removal
Velocity
(ft/s)
Cross
sectional
area (ft2)
Top
Width (ft)
Average Upstream 0.34 10.80 72.28
Average
Downstream
0.43 10.75 66.02
Overall Average 0.41 10.77 67.32
Culvert Removal Analysis
Predevelopment
Velocity
(ft/s)
Cross
Sectional
Area (ft2)
Top
Width (ft)
Average Upstream 0.33 11.24 73.17
Average
Downstream
0.43 10.75 66.02
Overall Average 0.41 10.86 67.51

65. Culvert Removal Cost Analysis
Component Name Price ($/unit) Quantity Cost ($)
Compacted Earthfill $5.75 per yd3 3 yd3 $17.25
Hydraulic Excavator $117.15 per hour 18 hr $2,108.70
Heavy Equipment
Operators
$33.69 per hour 18 hr $606.42
Aggregate, Gravel $35.73 per yd3 14 yd3 $500.22
Low Water Crossing
Planks
$30 per plank 30 planks $9,000.00
Mobilization $262.64 per item 1 excavator $262.64
Total Cost $12,495.23

66. Flooding Solution Caparison
Average Velocity
(ft/s)
Average Cross
Sectional Area (ft2)
Average Top Width
(ft)
Predevelopment 0.41 10.86 67.51
Channel Filling 0.31 37.16 70.25
Weir Installment 0.0571 118.2 100.1
Culvert Removal 0.41 10.77 67.32

67. Cost Comparison
Restoration
Technique
Final Cost
Channel Filling $8,361.59
Weir Installment $3,598.73
Culvert Removal $12,495.23
● When compared the weir
was concluded to be the
most cost-effective option
● Installing a weir requires less
time for installment as well
as lower material costs

68. Weir Installation Test for a Major Storm Event
● Modeled after Hurricane Matthew (category 5)
● 1,000 year storm event
● Peak flowrate at reference watershed: 1000 ft3/s

69. Major Storm Event Data
● Desired approaching velocity for a weir is 0.5 ft/s
● Flood simulation resulted in an approaching velocity of 1.86 ft/s
○ The resulting velocity is high and may damage the weir if placed similarly
to the model

70. Weir Modeled with AutoCAD
Front View
Top View

71. Soil Model-Weir
Tanner Road
Weir
Legend
Original Channel
Base
Areas of Soil
Build-up
Water
TannerRoad
Weir

72. Take Home Messages

73. Take Home Messages
● In its current state, the Francis Marion National Forest hydrology is
compartmentalized due to previous agricultural practices
● Case studies and further research show methods such as ditch plugs, culvert
removal, tile breaks, and channel filling have proven to minimize the effects of
channelization
● Using modeling programs such as HEC-RAS allow for different solutions to
be simulated leading to making the best possible choice for a solution

74. Our Recommendation
● By analyzing a low level storm event in HEC-RAS, it was determined that the
addition of a cement weir with a soil berm would be the most effective at
reducing flowrates and increasing top width flooding to maximize the area of
the hydric soil
● Using preliminary cost analysis, this is also the most cost-effective design
option
● The berm will limit sediment transportation and seedbank dispersion for
promoting the growth of wetland vegetation

76. Acknowledgements
USDA Staff
Dr. Carl C. Trettin, Team Leader & Suprv. Research Soil Scientist
Mrs. Julie A. Arnold, Forestry Technician
USACE Wetland Specialist
Mrs. Andrea Hughes
USACE Wetland Regulatory Deputy
Mrs. Robin Socha
Clemson University Staff
Dr. Christophe Darnault, Ingénieur, Ph.D.

77. Thank You!