20020730 Ver 4_More Info Received_20220817 (9)

Summary of NOAA-NCCOS data collection at
Battleship Park in support of the "Living
with Water" project
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NOAA National Centers for Coastal Ocean Science
Jenny Davis, Carolyn Currin, and Michael Greene
October 2019

Background
In 2019, NCCOS researchers entered into a Memorandum of Agreement with the USS North
Carolina Battleship Commission to provide baseline data to support the design of the "Living
with Water" project. Battleship Park site managers are interested in using a living shoreline
approach to redesign the southern shoreline of the battleship berth which is currently covered
in loose rubble. The goal is to have a more aesthetically pleasing shoreline that is resilient to
flooding. In an effort to address regular tidal and rainfall flooding of the adjacent parking lot,
the Living with Water project also involves conversion of the western region of the current
parking area to tidal wetland.
In addition to playing an advisory role in the design of the living shoreline and participating in
planning, proposal writing, and outreach activities on an ad hoc basis, NCCOS researchers
installed a water level recorder to support determination of elevation/inundation patterns
along the project shoreline, conducted an RTK-GPS supported survey of the occurrence and
distribution of existing vegetation on the project shoreline, and collected additional
topographic surveys to determine current elevations of the parking areas at Battleship Park.
Figure 1. Loose rubble covering current southern shoreline of the battleship berth.

Methods
Water Level Sensor Deployments
For analysis of water levels within the battleship berth, a HOBO (Onset Corporation, Bourne
MA) pressure sensor was attached to a piling on the boardwalk to the east of visitor center. An
additional pressure sensor was installed on -site (in the vegetation near the visitor center
entrance) so that water pressure data could be corrected to water level by adjusting for
barometric pressure. The water pressure sensor was housed in a PVC casing fixed to a solid
steel pole. The pole was attached to the wooden boardwalk piling such that the sensor was
several inches above the sediment surface (Figure 2). The sensors were initially deployed on
8/6/2018 and collected data continuously at 5-minute intervals until 1/10/2019 with one data -
download on 10-27-18. A metal bolt was installed in the wooden piling and the precise
elevation of the screw was established by VRS RTK-GPS (Virtual Reference Station, Real Time
Kinematic) referenced to a nearby NGS benchmark (PID EA 3063) and a local elevation control
mark (concrete base of lamp post). The precise elevation of the submerged pressure sensor (-
0.69 m NAVD88) was determined by difference of the distance from the screw to the sensor.
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PVC housing
Hobo Sensor
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Figure 2. A - Schematic of water level sensor mounting system showing measured distance between the metal screw; blue symbol)
and sensor. B. The mounting system was attached to the piling indicated by the red circle.

Vegetation/Elevation Surveys
On September 26, 2019 the southern shoreline of the battleship berth was surveyed to classify
the existing plant community and establish the range of elevations over which each identified
species was distributed. NCCOS researchers walked the length of the southern shoreline
starting at the confluence of the battleship berth and the Cape Fear River and extending
westward to a point almost in line with the ship's bow. The elevation range over which each
species occurred was established by VRS RTK-GPS. Error (+/- 0.02 m) was estimated from
repeated measures on a local control mark over the course of the survey.
Parking Lot Elevations
We conducted an additional survey using a vehicle
mounted GPS receiver (Figure 3) to provide baseline
data on elevations throughout the existing parking lot
regions. With the receiver mounted to the truck (and
after having established the offset between the
receiver and ground elevation) we drove slowly
throughout both the east and west sections of the
parking lot and along the length of Battleship Road
collecting data in continuous topo mode at 10 second
intervals.
Results
Water Level
Figure 3. GPS rover attached to truck for driving -based
elevation survey of parking lot and Battleship Road.
Water level patterns recorded by the Battleship Hobo sensor were identical to those recorded
at the National Water Level Observation Network (NLWON) Station which is 1 Km downstream
of the Battleship site in the Cape Fear River (NWLON 8658120) with exceptions when water
levels were below the elevation of the Hobo sensor (Figure 4). This finding establishes the
appropriateness of using the Cape Fear National Water Level Observation Network (NWLON
8658120) station data for analysis and projections of conditions at the project site. Both
records illustrate the impact of Hurricane Florence whose flood waters reached the site on
September 15, 2018 resulting in high tide water levels that were elevated by — 1m and low tide
water levels that were elevated by 1.5m. Low tide levels did not return to pre -storm levels until
the second week of October. While the flooding associated with Florence was unprecedented,

these data illustrate the susceptibility of this site to prolonged periods of inundation associated
with rainfall events in the Cape Fear watershed.
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NC Battleship HOBO
Wilmington 8658120
Battleship HOBO
9/1 /18 10/1 /18 11 /1 /18 12/1 /18 1 /1 /19
Date
NC Battleship HOBO
Wilmington 8658120
Battleship HOBO
-0.7 m
1 /1 /19 1 /2/19 1 /3/19 1 /4/19 1 /5/19 1 /6/19 1 /7/19 1 /8/19 1 /9/19 1 /10/19
Date
Figure 4. Comparison of water level data collected in Battleship basin with that collected at Cape Fear River NWLON station.
Top panels shows entire duration of Hobo water level record. Bottom panel provides a closer look at subsample of the record.
Note that water levels frequently fell below the elevation of the hobo sensor (-0.7 m NAVD88).

Vegetation
The current shoreline of the Battleship berth is characterized by a wide variety of wetland
plants ranging from the invasive Phragmites australis on the western and northern shoreline, to
a mix of species characteristic of freshwater to brackish wetlands along the southern shoreline.
While species distribution does not appear to be dominantly controlled by elevation (Table 1),
there is a strong spatial gradient in their presence with salt -tolerant species like Spartina and
Distichlis more abundant near the river and less salt -tolerant species like Typha and Eliocharis
occurring only in the southeast corner of the battleship basin (Figure 5).
The occurrence of fresh water wetland plants near the southeast corner of the basin is likely
indicative of the flow of fresh water through large Phragmites-dominated marsh to the west of
Battleship Park. Site managers have noted that water from this parcel tends to flow southward
along the treeline at the western extent of this parcel until it is diverted back toward the
battleship basin by Battleship Road. We speculate that this freshwater drainage leads to low
salinity porewater conditions that are conducive to the growth of the less salt tolerant species
documented here.
Table 1. Species identified during shoreline survey and the elevations at which they occurred.
Species
Number of observations
Elevation range of occurrence
Spartina alterniflora
11
-0.28 — 0.33
Phragmites australis
8
-0.24 — 0.86
Spartina cynosuroides
4
-0.21— 0.71
Sagittaria lancifolia
2
0.1-0.4
Distichlis spicata
10
0.14 — 0.71
Eliocharis sp.
1
0.23
Scirpus sp
2
0.35-0.66
Borrichia frutescens
1
0.45
Triadica sp.
1
0.49
Juncus effuses
1
0.63
Typha latifolia
1
0.64
Iva frutescens
2
0.65 - 0.91
Upland lawn grasses
4
0.7 - 1.44
Hydrocotyle sp.
1
1.1
In part, the goal of determining the growth elevations of each species was to facilitate a living
shoreline design that would be more conducive to the establishment of native species than to
Phragmites. While we accept the likelihood that Phragmites will eventually take over this
shoreline, our intention is to promote the quick establishment of a dense community of native
vegetation which we believe will be the best defense against Phragmites colonization.

Additional elevation surveys conducted by driving along the center line of the paved regions of
the parking lot and battleship road indicated elevations ranging 0.94m to 1.4 m (NAVD88) in the
eastern section of the parking area with the lowest values near the visitor center. Elevations in
the western region of the parking lot ranged from 0.55m to 1.1 m (NAVD88); note that these
values are within the elevation growth range of several of the shoreline plant species.
Vegetation
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D Eleo€haris
D Hydro€otyle
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Phrag
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5 €yno
5agittaria
C) 5€irpus
C) Triadi€a
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Parking lot
elevation
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Figure 5. Elevation and vegetation survey data. Colored points along the shoreline indicate the occurrence of wetland plant species. Colored
points along roadways indicate elevations.
Additional Accomplishments
We have purchased the supplies necessary to install an elevation benchmark near the project
site. This mark will facilitate the long-term monitoring of this project by providing an easily
accessed vertical control point in close proximity to the restoration site to facilitate monitoring
fine -scale changes in surface elevation time as the site matures. The mark will be installed and
its precise elevation determined upon completion of the build phase of the project.

Next steps
We recommend a thorough analysis of elevations and flow conditions in the property directly
west of Battleship Park. Understanding the influence of water movement through this area on
the project site will be critical to project design. Installation of porewater samplers as well as
water level sensors would provide valuable insight into the hydrology of this parcel and its likely
impact on the wetland to be created as part of the Living With Water Project.
For further questions contact
[e-mail]

To investigate patterns of inundation across the Battleship property, a series of compact water level and salinity
sensors were installed at ground level. Sensors logged data continuously at 10 minute intervals over the course of
a year
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Question 1: Does the water level record from the NOAA long term tide gauge in the Cape Fear
adequately represent water levels in the Battleship berth?
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Rationale: even small differences between the two would be important to understand for living shoreline design
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1 /1 /19
NC Battleship HOBO
Wilmington 8658120
Battleship HOBO
-0.7 m
1 /2/ 19 1 /3/ 19 1 /4/ 19 1 /5/ 19 1 /6/ 19 1 /7/ 19 1 /8/ 19 1 /9/ 19 1 / 10/ 19
Date
A single water level sensor was
installed on a boardwalk piling
near the stern of the ship in 2019.
No detectable differences were
found between water level trends
at this site and those measured at
the nearby NOAA long-term tide
gauge in the Cape Fear River.

Question 2: Are there differences in timing/magnitude of water levels across the
Battleship property?
Rationale: differences would indicate restrictions to water flow that could be alleviated by re -design
(eg. a culvert that is too small...)
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Water level sensors were installed at
the remaining 3 stations in July of 2020
and have been collecting data ever
since. The timing and magnitude of
Sensor high tide signals is consistent among all
1 3 sensors suggesting that water moves
2
4 freely across the site

Question 3: Are there measurable salinity differences across the site?
Rationale: if rainwater is an important driver of flooding in the road/parking lot entry area, we should
be able to detect that in the salinity data
12
All salinity values below 1 ppt removed
y = 0.98 x + 0.44; r2=0.66
0 4 8
Salinity @ Battleship (ppt)
Month
1
2
3
4
5
9
10
11
12
For most of the observation period, salinity values
In the ditch near Battleship Road were similar to
those measured within the basin. We did
measure fresher values in the ditch during parts of
April are currently investigating these values further.

Question 4: What is the frequency of flooding events that influence Battleship Road?
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Battleship NC - Days with Flooding by Elevation
July 2020 - June 2021
99.7%
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Flood Level (m NAVD88)
Colored circles represent elevation data collected by *This area was inundated for part of the day on almost
NOAA during a 2019 GPS survey half of all days last year