Data Storage Plan
‘Wave dissipation and transformation over coastal vegetation under extreme
hydrodynamic loading’
HyIV-FZK-07
Grosser Wellenkanal (GWK), Hannover
Authors: Iris Möller, University of Cambridge; Tom Spencer, University of Cambridge; Kai
Jensen, University of Hamburg; Franziska Ruprecht, University of Hamburg; Antonia Wanner,
1
University of Hamburg; Bregje van Wesenbeek and Guido Wolters, Deltares; Maike Paul,
University of Hannover; Tjeerd Bouma, NIOZ; Matthias Kudella and Stefan Seiberling GWK
Status form
Document information
Project acronym
HyIV-FZK-07
Provider
Facility
Title
Forschungszentrum Küste (FZK)
GWK
‘Wave dissipation and transformation over coastal
vegetation under extreme hydrodynamic loading’
1st user group contact (name/email)
2nd user group contact (name/email)
1st provider contact (name/email)
Iris Möller, im10003@cam.ac.uk
Tom Spencer, ts111@cam.ac.uk
Stefan Schimmels, Schimmels@fzk-nth.de
2nd provider contact (name/email)
Start date experiment (dd-mm-yy)
Start date experiment (dd-mm-yy)
Matthias Kudella, kudella@fzk-nth.de
10-09-13
25-10-13
Document history
Date
26-2-2013
6-8-2013
Status
Draft
Final Draft
Author
Iris Möller
Iris Möller
Reviewer
Approver
Document objective
This document describes the planned experimental setup, the test programme and a
description of the various measurements and their location in relation to the two vegetated
test-sections (consisting of Spartina and Elymus species respectively). It also outlines the
nomenclature that will be used to store data as it is being generated. The data storage plan
may be adapted during experimentation. When all data has been obtained, the data storage
plan should be updated to the data storage report, in which data is described so that others
may use them.
Acknowledgement
The work described in this publication was supported by the European Community’s
Seventh Framework Programme through the grant to the budget of the Integrating Activity
HYDRALAB IV, Contract no. 261520.
2
Disclaimer
This document reflects only the authors’ views and not those of the European Community.
This work may rely on data from sources external to the HYDRALAB IV project Consortium.
Members of the Consortium do not accept liability for loss or damage suffered by any third
party as a result of errors or inaccuracies in such data. The information in this document is
provided “as is” and no guarantee or warranty is given that the information is fit for any
particular purpose. The user thereof uses the information at its sole risk and neither the
European Community nor any member of the HYDRALAB IV Consortium is liable for any use
that may be made of the information.
Contents
Status form.............................................................................................................................................. 2
Document information ........................................................................................................................... 2
Document history ................................................................................................................................... 2
Document objective ................................................................................................................................ 2
Acknowledgement .................................................................................................................................. 2
Disclaimer................................................................................................................................................ 3
Contents .................................................................................................................................................. 3
1 Objectives............................................................................................................................................. 4
2 Experimental setup .............................................................................................................................. 4
2.1 General description....................................................................................................................... 4
2.2 Definition of the coordinate system ............................................................................................. 5
2.3 Relevant fixed parameters ............................................................................................................ 5
3 Instrumentation and data acquisition ................................................................................................. 8
3.1 Fixed instrumentation ................................................................................................................... 8
3.2 Non-intrusive plant and soil observations .................................................................................... 9
3.2 Definition of time origin and instrument synchronization ......................................................... 10
3.3 Measured parameters ................................................................................................................ 13
4 Experimental procedure and test programme .................................................................................. 14
5 Remarks.............................................................................................................................................. 17
3
1 Objectives
The main aim of this experiment is to provide data on the interaction between a salt marsh
vegetation canopy, surface sediment and waves under real-scale hydrodynamic loading. The
main objectives are to:
1. quantify the role of vegetation on wave attenuation under extreme conditions that
are essential for flood defence designs;
2. identify water depth / wave height / wave steepness thresholds that mark the
transition from (a) conditions in which vegetation has a negligible effect on wave
energy to (b) those regimes where vegetation significantly affects waves, to (c) those
conditions that cause bed/canopy/plant ‘failure’/’breakage’;
3. quantify the forces and response of two species types (Elymus and Puccinellia) at the
front of the vegetated section to the various depth/energy regimes;
4. quantify the effect of a non-vegetated marsh platform on waves, for comparison
with the effects of the vegetated platform (control condition).
2 Experimental setup
2.1 General description
A vegetated test section of 39.44 m length will be built up of 200 cut (field excavated) pieces
of saltmarsh turf of size 1.16 x 0.76 m each. The 39.44 m long section will be split in two
sections. In the first (front) section, Elymus and Puccinnellia species plant turf elements will
be placed in parallel next to each other width-wise, for a distance of 3.48m (i.e. three marsh
blocks deep). Behind this front set of 6 x 3 marsh blocks, the remaining 182 pieces of turf
will be arranged in a chequerboard pattern to simulate a mixed marsh community, as
illustrated in Figure 1. At the front end of the platform with vegetation, a flat sand surface of
13 m length will be built up to the level of the marsh surface. In front of this, a ramped sand
slope will be built (slope of 1:10) for a distance of 7 m, in front of which the slope will be
1:1.7 over a distance of 1.2 m. The surface of the flat sand section in front of the vegetation
blocks will thus be at 1.3 m above the flume base. The slope will allow the waves to shoal
and/or break, as they would do in a natural shallow water marsh setting. The vegetated
platform will be raised to a height of +1.5 m above the base of the tank by constructing a 1.2
m high sand base on top of which a geotextile surface will be placed with the marsh pieces
placed onto the geotextile by fork lift truck. This is required because of the minimum usable
water level of ca +2m within the GWK flume. To the front and the rear of the vegetated
section, the sand base will be raised so that the surface of the sand is level with the
vegetated section surface. The sand layer of the platform and slope in front of and behind
the vegetated section will be ‘reinforced’ such that it remains stable under the generated
wave conditions and does not change its morphology. Sand movement into the vegetated
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test section should thus be avoided. Conditions of 2-4 different water depths (0.6, 1.0, 1.5
and 2.0 m above the test section, with the priority for 2.0 and 1.0 m depths) and five wave
heights (HS: 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 0.9, and 1.0 m) will be simulated. For all test run days,
irregular waves will be used first, followed by a series of regular wave runs of shorter
duration. An irregular wave test-run will consist of ca. N = 1000 waves. A total of 9 GWK
owned side-mounted wire wave gauges will be deployed, with 3 each in front of / behind
the test section to quantify wave reflection/transmission, and 3 deployed on the test
section itself. GWK will also supply an additional 15 pressure gauges that will be placed on
the test section as shown in Figure 1. GWK will supply three Electro-Magnetic Flowmeters
(EMFs) that will be placed on the mobile crane (see Figure 2). For each run, full wave spectra
and wave parameters (height, period and steepness) will be recorded (Location of GWK
wave gauges is shown in Figure 1, but the 15 bottom-mounted pressure gauges will provide
additional high-frequency pressure records for conversion to wave spectra). Tests will be
conducted with intact and removed (mowed) vegetation, with the latter tests acting as
control runs to determine the effect of the vegetation as opposed to the topographic effect
of the platform.
The entire vegetated test section will be illuminated for the benefit of the plants, at least
whenever these are emergent between experimental runs, by a total of 60 lamps (GE 750W
400V PSL or equivalent) mounted along the side of the flume (see Figure 1).
Access walkway platform supports
Supports for an access walkway platform will be fixed to the bed of the flume at four
positions, so that the surface of the walkway is approximately 30 cm above the soil base (to
prevent plants from breaking when the walkway is placed) and so that the forward facing
edge of the walkway is at positions that allow measurements coincident with (a) flow
recording (Vectrinos) in front section at 2.1 m into the vegetation, (b) wave recording on the
test section at 8.4 m into the vegetation, (c) wave recording and video observations of plant
movements at 20.3 m into the vegetation, and (d) wave recording at 35.3 m into the
vegetation.
2.2 Definition of the coordinate system
The origin is positioned at the wave board, on the front side of the flume (the end of the
building at which the offices are located), at the bottom. The horizontal x-axis is positive in
the direction of wave propagation towards the structure. The horizontal y-axis is negative
along the wave board from the back towards the office-side of the board. The x- and ydirection are also shown in Figure 1. The vertical z-axis is positive upwards from the base of
the flume.
2.3 Relevant fixed parameters
The test section structure is the same in all test runs. The water depth is varied between 0.6
and 2.0 m above the surface of the vegetated test section in individual test runs and is
5
lowered to below the root zone of the vegetation (ca. 40 cm below the vegetated marsh
surface) after each two days of submersion during the experiment. A list of parameters used
in the table of experimental runs is given in Table 1 below.
Table 1: Parameters used in experiment to describe set-up and wave conditions
hF= marsh surface height above base of
tank
h=water depth above tank base
hT = water depth above marsh surface
Hs= significant wave height
Tp=peak wave period
sop=wave steepness
hVEG=height of vegetation
6
Figure 1: Experimental layout and coordinate system
7
3 Instrumentation and data acquisition
3.1 Fixed instrumentation
Wave gauges
A total of 9 GWK owned wave gauges will be deployment, with 6 (3 each) positioned in front
of / behind the test section to quantify wave reflection/transmission, and 3 positioned at
intervals across the test section.
In addition, 15 GWK pressure sensors will be deployed as shown in Figure 1, with an
additional three on the crane pole (see Figure 2). One of the 15 bottom mounted pressure
sensors will be placed in the immediate vicinity of the first wall-mounted wave gauge and
alongside a calibrated staff that is being monitored by video camera as well as a CCRU
pressure sensor to allow calibration and comparison of the different measurement
techniques (video, bottom pressure from GWK and CCRU Druck PDCR1830 gauge, and GWK
wall-mounted wave gauge).
Current meters
Three Electromagnetic Flow Meters (EMFs)) will be positioned near the drag sensors (strain
gauges) at the front of the test section at 0.05, 0.25, and 0.55 m above the bed. In addition,
three Acoustic Doppler Velocimeters (ADVs) will be mounted on the crane-mounted
movable pole as illustrated in Figure 2.
Current profilers
Two current velocity profilers (Vectrinos) will be deployed, each at a distance of 1.7 m into
the vegetated section. One at a distance of 1.14 m distance from the non-concreted side of
the flume immediately above the canopy of vegetation species 1. The other will be deployed
immediately above the canopy of species 2 at 3.42 m distance from the non-concreted side
of the flume (instruments to be provided by NIOZ and CCRU).
Strain gauges
Four force transducers (drag sensors) to which plant mimics of pioneer saltmarsh species
will be attached will be placed at the front end of the test section to measure the loading on
the plants (instruments from NIOZ).
Video recording
A GWK camera will be set up at 5.5 m (position of wave gauge 3) in front of the vegetation,
looking down the flume over the vegetated section; Another GWK camera will be set up at
5.5 m behind the vegetated test section, looking back over the test section. Two further
8
GWK cameras are to be set up behind the two glass windows on the side of the tank to
observe plant movements of both vegetation species with continuous (25fps) video
recording. A separate fixed video camera (25fps) will be supplied by the experimental team
to capture wave induced water level fluctuations against a calibrated staff at the position of
the crane-based EMF measurements, the GWK wire-wave gauge, and the CCRU pressure
sensor.
3.2 Non-intrusive plant and soil observations
Netting of floating debris
All floating organic debris will be removed after each test (or set of tests) from the water
surface using a net (1 cm mesh size) that is dragged along the water surface from the front
end of the vegetated test section to the end of the tank. This will serve the purpose of
reducing the interference of the organic debris with wave gauge operation and will also
allow the possibility for the debris to be collected and bagged, for analysis in the laboratory
(to determine dry weight as an indicator of plant material removal in relation to incident
hydrodynamic energy level). Removal of any debris not caught by the net will be achieved
through small hand-held nets at the end of long poles.
Soil surface profiles
Whenever the vegetated section is drained to allow plant oxygen supply (i.e. after each 2
days of submergence), soil surface elevations will be determined by using a 4.6 m long metal
bar that will be fixed to the mobile walkway platform at a distance of 10-15 cm from the
platform edge across the flume. The bar will rest at a height of ca 40cm from the soil bed (ca
10 cm higher than the surface of the platform). A calibrated pin will be lowered vertically
onto the soil surface through pre-drilled holes at distances of 20 cm along the metal bar to
determine the elevation of the soil surface to millimetre accuracy (i.e. providing 20 readings
of soil surface elevation at each of four bar positions along the vegetated test section) (see
above for location of walkway platform).
Plant structure measurements
Whenever the vegetated section is drained to allow plant oxygen supply (i.e. after each 2
days of submergence), plant stem density and height will be recorded at a number of
locations at each walkway position.
Plant vitality measurements
In the front section of the two vegetation species, the overall stress status of each species
will be quantified by using PAM (pulse amplitude modulation) fluorescence measurements
9
(University of Hamburg). After completion of all test runs, the PAM fluorescence signals of
the plants will be quantified by the Applied Plant Ecology Group of Hamburg University. To
quantify abiotic stress conditions, redox potential and O2 concentrations will be measured in
the rooting zone (University of Hamburg) prior to and after the experimental run sequence
at a total of N = 20 locations within each of the two vegetated sections (i.e. for each species).
3.2 Definition of time origin and instrument synchronization
Readings of all GWK wave and pressure gauges and EMFs are logged with one data
acquisition system. The system takes care of synchronisation. The readings are sampled at
40Hz.
For the additional pressure gauge, CCRU will synchronize data logger time with the timing of
the GWK wave recording system to ensure synchronized data acquisition. Readings for
these records are sampled at 4Hz.
The velocity profiling instrumentation will be synchronised / checked against the data
logging system and the GWK system prior to the start of each experimental run.
Force transducer measurements will be synchronised manually with the remainder of the
experiment by synchronising equipment logging times at the start and end of each day (and,
if possible, throughout the day, or before/after each experimental run).
10
Table 2: Position of instrumentation
11
Table 2: Position of instrumentation (continued)
12
3.3 Measured parameters
Fixed instrumentation parameters and the timing/frequency with which they will be
measured are listed in Table 3 below.
Table 3: Parameters recorded by fixed instrumentation
Instrument
GWK wave gauges
Number of locations Parameters
9
Full spectra and
wave characteristics
GWK pressure gauges
15 (+ 3 crane Full spectra and
mounted)
spectrally derived
wave characteristics
CCRU pressure gauges
1
Full spectra and
spectrally derived
wave characteristics
GWK EMF
3
??
GWK ADV
3
Velocity at three
heights above the
vegetation canopy
(crane mounted)
Accellerometer
1
Accelleration at one
height above the
vegetation canopy
(crane mounted)
CCRU/ NIOZ Velocity 2
Velocity and energy
profiler
spectrum
NIOZ Strain gauge
4
??
GWK Continuous video 4
Video file
camera
Team camera
1
Video file of water
level fluctuations
CCRU camera
1
*.jpg images
Plant vitality
measurements
(PAM) 10
???
Plant height and stem 4
density
Mean and standard
deviation
Dry biomass detritus
Dry
weight
of
floating debris
Surface
elevation
relative to tank base
along
cross-tank
transect at 20 cm
intervals
1
Elevation (soil surface) 4
profiles
Timing/Frequency
Continuous
Continuous
Continuous
Continuous
Continuous
Continuous
Continuous
Continuous
Continuous
Continous
Before/after each
test-section
submergence
Before/after each
test-section
submergence
During
every
exposure of test
section surface
After every (set of)
run(s)
During
every
exposure of test
section surface
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4 Experimental procedure and test programme
The planned test programme is represented in Table 4, but is subject to changes depending on the first test results.
Table 4: Experimental run sequence.
(continued on next page…)
14
Table 4 (continued from previous page):
(continued on next page…)
15
Table 4 (continued from previous page):
16
5 Remarks
Water depths of 1.5 and 0.6 m may be eliminated if time is short. They are less critical than
the other depths.
We propose lowering the water level after Hs = 0.2 m tests (if no obvious damage to the test
section can be observed).
Exposure of the test section to allow oxygen to the plants and to allow vegetation and soil
profile measurements should occur every two days. A full day of exposure is required.
The test section should be exposed after day 2 - when threshold from no-to-some
attenuation has been reached. Then we suggest to move onto runs 45-56 (and some of the
optional (highlighted in Table 1) ones) before returning to run 13. Care needs to be taken to
stress the bed incrementally and stop before serious erosion occurs. This may involve
jumping between water depths and occasionally lowering level to expose the bed to inspect
it.
If small incremental steps are always performed, then we should be able run the full test
length for each test. Shorter duration may be required only for sudden changes in loading.
For regular waves, non-breaking conditions are most important to be captured, so it may be
decided to eliminate the breaking / transitional regimes.
17