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Data Storage Report

Wave-induced bedform dynamics in mixed cohesive–noncohesive sediments: a fundamental re-calibration of

sediment transport models in coastal environments

HYIV-HULL-06

TES, University of Hull

Author: Stuart McLelland, University of Hull

Status form

Document information

Project acronym HYIV-HULL-06Provider University of HullFacility TESTitle Wave-induced bedform dynamics in mixed

cohesive–noncohesive sediments: a fundamental re-calibration of sediment transport models in coastal environments

1st user group contact (name/email) Dr Joris, Eggenhausen, J.T.Eggenhuisen@uu.nl 2nd user group contact (name/email) Dr Jaco Baas, J.Baas@Bangor.ac.uk 1st provider contact (name/email) Stuart McLelland, S.J.McLelland@hull.ac.uk 2nd provider contact (name/email) Dan Parsons, d.parsons@hull.ac.uk Start date experiment (dd-mm-yyyy) 19-08-2013End date experiment (dd-mm-yyyy) 04/10/2013

Document history

Date Status Author Reviewer Approver20/09/2014 Final Stuart

McLellandDan Parsons Stuart

McLelland

Document objectiveThis document describes the data that was obtained during this project and how it was stored, so that others than the people immediately involved may use the data for their research.

AcknowledgementThe 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.

DisclaimerThis 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

1 Objectives......................................................................................................................... 4

2 Experimental setup...........................................................................................................42.1 General description..................................................................................................42.2 Definition of the coordinate system..........................................................................42.3 Relevant fixed parameters.......................................................................................4

3 Instrumentation and data acquisition................................................................................63.1 Instruments..............................................................................................................63.2 Definition of time origin and instrument synchronization..........................................73.3 Measured parameters..............................................................................................7

4 Experimental procedure and test programme..................................................................7

5 Data post-processing.......................................................................................................9

6 Organization of data files..................................................................................................96.1 ABS data (Aquascat binary format).......................................................................116.2 ADV data (Nortek binary format)............................................................................116.3 URS data from fixed array (text format).................................................................116.4 URS data from array mounted on traverse (text format)........................................116.5 Wave Guage data (text file format)........................................................................126.6 Vectrino data (Nortek binary format)......................................................................12

Appendix 1: Experimental Procedure Instructions..................................................................13

1 ObjectivesThe principal aim of the proposed experiments is to investigate near-bed turbulence and sediment transport interactions over rippled beds of clay-sand mixtures under waves. Such cohesive mixtures may have a yield strength that affects the timing of first appearance of bedforms from a flat sediment bed, and they are subjected to demixing (or winnowing) processes, which will in turn affect the rate of bedform development which will alter the equilibrium size and shape of the bedforms. The overall aim of this project will be achieved through three specific objectives:1. Quantify interactions of near-bed hydrodynamics, sediment transport dynamics and turbulence over rippled beds formed by waves using state-of-the-art measurement techniques. This will help to greatly improve modelling approaches by enabling rigorous model-data comparisons, representation of near-bed turbulence behaviour, and assessment of appropriate boundary conditions.2. Quantify how clay-sand mixtures and resultant bed cohesion affect bedform evolution, boundary layer processes (including turbulence), and sediment transport, through processes of clay winnowing and near-bed turbulence modulation. The unique results, will also allow us to directly assess scaling issues in previous work.4. Synthesise results from objectives 1 and 2 to test the predictive ability of present state-of-the-art sediment transport models in mixed sediment environments and re-calibrate such models with the trajectories from the phase space explored within the experimental results in objectives 1-3.

2 Experimental setup

2.1 General description

The set-up used for these experiments was a straight 1.6 m wide and 9.8 m long, channel located in the centre of the flume. Regular water surface waves were generated using the two central 0.75m wide wave paddles. At the end of the flume, the waves were dissipated using perforated board with a porosity of 15%, mounted at an upstream-dipping angle of 6°. The porous slope dispersed wave energy and thus minimised wave reflections (reflections were estimated to be <10%). The floor of the channel was covered with a 0.1-m thick layer of mixed sediments with the proportion of clay and sand being varied for different experiments. The experiments used saline water (salinity: ~19 psu). Figure 2.1 shows the experimental set-up.

Five test were performed each with a different bed sediment composition.

2.2 Definition of the coordinate systemThe axes are defined on the drawings shown in Section 2.1. The x-axis origin is at the front of the wave paddles. The y-axis origin is located

2.3 Relevant fixed parametersThe initial bed surface was always flattened. The water depth was fixed at 0.6m in all experiments. All runs used the same wave generator settings. The wave height and period were 0.19 m and 2.5 s. Based on linear wave theory, these parameters yielded a wave length of 5.7 m, a maximum near-bed orbital velocity of 0.34 ms-1, and a maximum near-bed orbital diameter of 0.13 m.

Figure 2.1: Experimental set-up

3 Instrumentation and data acquisition

3.1 Instruments The following instruments were mounted on a on a frame at x = 4.3 m:

1. optical backscatter probes (OBS1-4) 2. downward facing acoustic backscatter probe (ABS) for measuring suspended

particulate matter concentration;3. sampling tube connected to an ISCO sampler for collecting in situ suspended

particulate matter (used for calibrating the OBS and ABS data) The vertical height of this tube could be adjusted;

4. downward and sideways facing acoustic Doppler velocimeters (ADV0-5)5. a VECTRINO profiler for measuring wave orbital velocities (Only used in RUN6),6. an array of 4 of acoustic bed scanners (URS9-12)

Instruments were located as close as possible without causing interference. Vertical profiles were obtained for distances in the range of z = 0.03 m and 0.6 m above the initial flat bed.

Next to the fixed frame just off centre was a 3-m long traverse, on which a 2DHV acoustic bed scanner was mounted with 8 acoustic bed scanners (URS1-8) to record spatio-temporal changes in bed height along a length of 2.5 m and spanning a width of 0.49 m.

Wave characteristics were measured with 4 wave gauges, mounted along the right-lateral side of the channel

At the beginning and end of each experiment sediment cores with a diameter of 20 mm and a maximum length of 120 mm were collected from the bed.

Figure 3.1 Vertical position of instruments located on fixed frame

Figure 3.2 Horizontal locations of instrumentation (showing range of movement for UR1-8)

Table 3.1: Instrument identification and probe serial numbersInstrument ID Serial umberADV0 N293ADV1 N306ADV2 N314ADV3 N288ADV4 N289ADV5 N298OBS1 STM1533OBS2 STM1530OBS3 STM1532OBS4 STM1531

3.2 Definition of time origin and instrument synchronizationFor each measurement period, the instrumentation mounted on the fixed frame were synchronized using an electronic pulse (except for the ISCO sampling which was controlled manually). Measurement using URS1-8 were taken separately

3.3 Measured parametersA number of parameters were measured using the instrumentation:

1. Flow velocity2. Bed elevation3. Suspended sediment concentration4. Suspended and bed sediment grain size5. Wave height

4 Experimental procedure and test programmeThe first experiment (Run 01) used well-sorted, medium-grained sand with a median diameter D50=0.496 mm. For each subsequent experiment, wet kaolin clay was thoroughly mixed into

the bed, so that the initial bed clay fraction, f0c, progressively increased from 3.2% (Run 03) to 5.5% (Run 06) (Table 4.1). Run 02 was a test run undertaken with irregular waves, however due to time constraints, no further irregular wave tests were undertaken. Before each run, the wet bed was flattened using a length of wood, taking care not to separate the clay and sand.

Before each experiment, these cores were collected at 7 equally-spaced locations at 3.9 m < x < 6.3 m from the wave paddles and y = 0.4 m from the right-lateral side of the channel. After draining the flume at the end of a run, sediment cores were collected from the rippled bed at 6 equally-spaced locations at 3.9 m < x < 5.9 m. These locations roughly coincided with 6 of the pre-run samples. The post-run samples comprised separate samples from the ripple crest and the ripple trough. Two additional samples were collected at (x,y) = (5.1,0.8) m and (x,y) = (5.1,1.2) m. All cores were sealed and frozen until further analysis.

A. B.

.Figure 4.1 Location of sediment cores taken at before (A) and after (B) experiments

Waves were generated at time intervals of 20-120 minutes, depending on the bedform development rate. Instrumentation mounted on the fixed frame was started approximately 2minutes after wavemaker was started and recorded continuously until wavemaker was stopped. The wave maker was temporarily switched off for ~15 minutes to permit full scanning with URS1-8 to collect bed morphology data.

ISCO samples were collected at z = 0.05 m and z = 0.38 m in Runs 03-06. Clean sand run Run 01 had a more extensive sampling strategy, but this was not maintained in subsequent runs due to time constraints.

Table 4.1 – Experimental Runs.

Run Initial bed sand fraction

Initial bed clay fraction

Equilibrium time

Equil. ripple height

Equil. ripple length

f0s (%) f0c (%) (minutes) He (mm) Le (mm)01 100 0 35 18 12203 85.4 3.2 38 20 12404 77.4 4.6 53 22 11905 71.2 5.3 345 20 13106 71.4 5.5 510 20 121

A log file HYIV-06-LOGFILE.txt contains a record of all experimental runs including wave activation periods and instrument recording details.

The experimental procedure instructions are summarized in Appendix 1.

5 Data post-processingSPM concentrations were determined from the ISCO samples using standard filtering. The filter paper had a diameter of 47 mm and a retention of 0.7 m. Some sample were also sampled using the LISST during experiments, but a problem with the machine means these data are likely to be erroneous.

Selected cores were cut into 1-cm discs while frozen. The discs were then dried overnight at 80ºC, and processed using a Malvern 2000 Laser Particle Sizer. This provided grain size distributions, from which statistical parameters, including median particle size and bed clay and bed sand fractions, were computed.

ADV and ABS data require post-processing using appropriate software.

6 Organization of data filesThe data files have been uploaded to a dedicated cloud computing repository – Microsoft OneDrive (see Figure 6.1) under which all project partners have full access to the datasets generated during the experimental access period. These data sets fall under the following broad categories:

ABS Data ADV data URS data Wave Gauge data Vectrino Data

There are also still photographic images and video files which are organized by date

Table 6.1 shows the measurement runs and the start and end time for each measurement epoch.

Run Epoch Number

Epoch Start Time

Epoch End Time

R01 1 000 020  2 020 050  3 050 080  4 080 110  5 110 140  6 140 170  7 170 200  8 200 230  9 230 260  10 260 290R02 1 000 030  2 030 060  3 060 090  4 090 120  5 120 150  6 150 180  7 180 210  8 210 240  9 240 270R03 1 000 015  2 015 030  3 030 045  4 045 060  5 060 090  6 090 120  7 120 150  8 150 180  9 180 210  10 210 240  11 240 270  12 270 300R04 1 000 010  2 010 015  3 025 040  4 040 070  5 070 100  6 100 130  7 130 160  8 160 190  9 190 220  10 220 250

Run Epoch Number

Epoch Start Time

Epoch End Time

R05 1 000 030  2 030 060  3 060 090  4 090 120  5 120 150  6 150 180  7 180 210  8 210 240  9 240 270  10 270 300  11 300 330  12 330 360  13 360 390  14 390 420  15 420 450  16 450 480  17 480 510R06 1 000 030  2 030 060  3 060 090  4 090 120  5 120 150  6 150 180  7 180 210  8 210 240  9 240 270  10 270 300  11 300 330  12 330 360  13 360 390  14 390 420  15 420 450  16 450 480  17 480 510  18 510 540  19 540 570  20 570 600  21 600 630

Table 6.1. Experimental measurement epochs

6.1 ABS data (Aquascat binary format)File Directory: HYIV-HULL-06-RXX-ABS where XX is the run numberABS 1-4 are recorded in files: HYIV-CW-RXX-ABSbase-TYYY-ZZZ.aqa

XX is the run numberYYY is the measurement start time ZZZ is the measurement end timeThese are ABS measurements taken prior to each epoch to estimate background suspended sediment concentrations.

ABS 1-4 are recorded in files: HYIV-CW-RXX-ABS-TYYY-ZZZ.aqaXX is the run numberYYY is the measurement start time ZZZ is the measurement end timeThese are ABS measurements taken whilst waves are running. Measurements are synchronized with other instruments mounted on the fixed instrument frame

6.2 ADV data (Nortek binary format)Files contained in directory: HYIV-HULL-06-RXX-ADVs where XX is the run numberADVs 0-5 are recorded in files: RXXTNNN.adv

XX is the run numberNNN is the measurement epoch numberThe ADV measurements are taken whilst waves are running. Measurements are synchronized with other instruments mounted on the fixed instrument frame

6.3 URS data from fixed array (text format)File format: 4 lines showing instrument start-up; then each line contains a timestamp (HH:MM:SS.sss), followed by measurements in from each instrument in numerical order (measurements in cm), final column is a check sum.

For exampleFile Contents ExplanationAN 1

Instrument set-upSetting number of analog channels to 1 Cmd>D13:08:18.279 34.15 43.67 43.29 43.57 151 HH:MM:SS.sss URS9 URS10 URS11 URS12 Check13:08:18.480 34.18 43.66 43.28 43.54 155 HH:MM:SS.sss URS9 URS10 URS11 URS12 Check13:08:18.680 34.19 43.67 43.28 43.59 154 HH:MM:SS.sss URS9 URS10 URS11 URS12 Check

File contained in directory: HYIV-CW-RXX-URS-Fixed where XX is the run numberABS 9-12 are recorded in files: HYIV-CW-RXX-URS-TYYY-ZZZ.dat

XX is the run numberYYY is the measurement start time ZZZ is the measurement end timeThese are URS measurements taken whilst waves are running. Measurements are synchronized with other instruments mounted on the fixed instrument frame

6.4 URS data from array mounted on traverse (text format)File format: 4 lines showing instrument start-up; then each line contains a timestamp (HH:MM:SS.sss), followed by measurements in from each instrument in numerical order (measurements in cm), final column is a check sum.

The format is the same as for the fixed array, except there are data from 8 URS probes.

The timestamp can be converted into distance, by dividing the measurements equally across the traverse distance of 2.5m (there is s short ramp-up and down distance at the start and end where no measurements are recorded)

File Directory: HYIV-CW-RXX-URS-Traverse where XX is the run number

Prior to each run, ABS 1-8 are recorded over at least one baseline traverse survey:Filename: HYIV-CW-RXX-URS-BaselineN.dat

where more than 1 baseline survey is completed N increments by 1.

After each run, ABS 1-8 are recorded over for a traverse survey:Filename: HYIV-CW-RXX-URS-PostTZZZ.dat

XX is the run numberZZZ is the measurement epoch end time

6.5 Wave Guage data (text file format)File format: 8 lines showing set-up; the last line gives the header for the data,each line contains, sample number, a timestamp (HH:MM:SS.sss), followed by data from 5 channels (note that channel 0 is not used). Measurements are in mV with calibration data collected each day to account for drift due to water salinity.

Files contained in directory: HYIV-HULL-06-RXX-WVGs where XX is the run numberWave Gauges 1-4 are recorded in files: HYIV-CW-RXX-WVG-TYYY-ZZZ.csv

XX is the run numberYYY is the measurement start time ZZZ is the measurement end timeThese measurements are taken whilst waves are running. Measurements are synchronized with instruments mounted on the fixed instrument frame

Calibration data is recorded in a separate dated directory which is dated. Calibration data were collected by moving the probes to different heights in still water. Note the calibration data show significant non-linearities in the wave gauge data due to the water salinity.Calibration files are recorded with a filename StillWater HXX (YYYmm)

XX is the height setting of the wave guage YYY is the effective water depth above the flume floor

6.6 Vectrino data (Nortek binary format)Vectrino data were only collected in run 6Files contained in directory: HYIV-HULL-06-R06-VectrinoVectrino recorded in files: HYIV-CW-WVG-TYYY-ZZZ.aaa.bb.Vectrino Profiler.ccccc.ntk-Traverse.adv

XX is the run numberYYY is the measurement start time ZZZ is the measurement end timeaaa, bb, ccccc are automated file labelsThe Vectrino measurements are not synchronized with other instruments mounted on the fixed instrument frame

Appendix 1: Experimental Procedure InstructionsDay One; Tank set up 1 – Prepare Sediment Mix

1. Calculate weight of clay required to reach desired clay bed fraction; account for % clay composition already in bed.

2. Open bag of clay under water in a large bucket. Beware that too much water will increase mixing difficulty in the tank.

3. Roughly flatted bed in flume, spread clay evenly onto surface. 4. Mix clay into bed using hand held mixers. This may take several hours to achieve a

homogenous bed. Do not knock instruments.

2 – Flatten Mixed Sediment Bed1. Using special purpose wooden board flatten bed to 10cm across the entire length of the

tank. If increased saturation is desired use hose in lab.2. Be careful not to add too much water as this will result in a separation of clay.3. Work from up wave towards down wave.4. Take syringe samples from locations marked in figure 1.5. Fill syringe holes with mixed sediment from down wave location.6. Re-flatten bed local to sample holes, this may be easier with a smaller leveller.7. Measure clay fractions in bed, if values are significantly different further mixing may be

required.

3 – Prepare Instrument Setup1. Put up wave ADV back in place using marks on panel wall2. Lower wave gauges to desired height above bed.3. Lower URS to desired height above bed.4. Move URS, ADV ect to desired position in measurement section.

4- Fill Flume1. Add salt to tank to reach 20 p.s.i2. Mix salt into water below floor level.3. Fill tank to 60cm’s above sediment surface. 4. While tank is filling deploy shear vane to measure strength of bed.5. This will likely require the rest of the day and possibly beginning of day 2.

Day Two; Experimental day1- Preparing for the Run.

1. Complete filling tank / check water level.2. Perform shear vane tests of the bed.3. Start URS flatbed scan; adjust #samples to cover just more than 2.55m at 0.01m/s & 4Hz

= 1020 [-].4. Raise URS probe holder out of water after scan.5. Put the gantry in the measurement position, which is marked “Coh W” on blue tape on the

outside of the gantry track.6. Lower the rack with instruments to the default position on the Z-traverse [195 mm]. Turn

on the ADV; fine tune the vertical position of the instruments such that the measurement volume of Probe0 is 0.03m above the initial flat bed. Note the actual z-position of the traverse in the Log-entry for this day.

7. Calibrate wave gauges [WVG calibration protocol].

2- Initiation of experiment1. Decide on the length of the interval [15/30 minutes].2. Start the four URS probes [Probes 9-12] on the instrument rack [@4Hz; interval T + extra

time to turn the experiment on]. 3. Trigger wave gauges, ADV, ABS/OBS with the magic black button. Check all are

recording. 4. Load appropriate wave parameters. Start waves. Set clock/alarm to stop waves after

interval [15/30 minutes excluding ramp].

3- Hydrodynamic recordings1. Run all instruments (except traverse) for 15 minutes, for (XX) hours, then for 30 minute

intervals for remaining time period.2. Take ISCO samples for LISST using procedure described in Appendix 4.3. After each interval stop waves.

4- URS Bed Scan1. Move gantry upstream to make room for URS cables running to traverse. Check OBS

probes don’t drag through ripple crests [Hm, in turbid water? Check distance ADV Probe0 to the bed? Note that the measurement location seemed to be an area of aggradation in the wave test runs].

2. Lower URS on traverse to lowest position [Note order: URS probe holder can collide with main instrument rack when moved along traverse whilst not fully lowered].

3. Start URS.4. After scan is complete, move URS back to Home position. Raise URS on traverse out of

water as high as possible, whilst not putting strain on the cabling underneath the lifting device [Note order: URS probe holder can collide with main instrument rack when moved along traverse whilst not fully lowered].

5. Put the gantry in the measurement position, which is marked “Coh W” on blue tape on the outside of the gantry track.

Repeat from Day2-2-1 until final URS scan.Drain tank [fully or to lip level?]

Day Three; Sample Collection1- Post Experiment Data Collection

1. When water is fully drained, remove up wave ADV2. Push gantry out of measurement section3. Raise wave gauges4. Take photographs of ripples (accuracy and detail.)5. Take syringe bed samples6. Make a 10cm wide trench in the centre of flume alone entire length of measurement

section. Edges should be at 70 degrees to horizontal.7. Take syringe samples in locations figure 1.8. Calculate mass bed clay concentration.