GREATER THAMES AOS MARGATE SANDS
SURVEY REPORT
Envision Mapping Ltd.
Newcastle upon Tyne
UK
March 2008
Thames AoS: Margate Sands Survey Report
Page 2 of 43 pages
Prepared for
Natural England/Entec
Title
GREATER THAMES AoS MARGATE SANDS SURVEY REPORT
Abstract
Contract reference:
2006-1012-Natural England/ENTEC-Wash & Thames
Report identification:
2006-1012-IS-Thames Survey Report
Document control
Rev.
Originator
Date
Status
0
Ian Sotheran
19/03/08
Draft
1
Ian Sotheran
27/03/08
Draft
Checked &
Approved
File index: P:\2006-1012-Natural England-Wash & Thames\REPORT\Thames Final Report\MAPPING
THE MARINE HABITATS OF GREATER THAMES Aos.Docx
Report:
Prepared by Ian Sotheran
Envision Mapping Ltd.
6 Stephenson House
Horsley Business Centre
Horsley
Northumberland
NE15 0NY
United Kingdom
T:+44 (0)1661 854 250
F:+44 (0)1661 854 361
NOTES:
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Contents
1
INTRODUCTION ................................................................................................. 5
2
METHODOLOGY AND ANALYSIS .................................................................... 5
2.1
2.2
2.3
Interferometric Bathymetric Sidescan Sonar survey ............................................................. 5
2.1.1
Equipment and deployment ............................................................................................................... 5
2.1.2
Processing .............................................................................................................................................. 5
RoxAnn single beam Acoustic Ground Discrimination System (AGDS) .............................. 6
2.2.1
Equipment and deployment ............................................................................................................... 6
2.2.2
Analysis ................................................................................................................................................... 6
Drop-down Video & Grab ......................................................................................................... 6
2.3.1
Equipment and deployment ............................................................................................................... 6
2.3.2
Analysis ................................................................................................................................................... 7
3
DATA INTERPRETATION .................................................................................. 7
4
RESULTS OF SURVEY ...................................................................................... 8
4.1
4.2
Summary of result outputs ....................................................................................................... 8
4.1.1
Swath bathymetry ................................................................................................................................ 8
4.1.2
Sidescan images .................................................................................................................................... 8
4.1.3
AGDS RoxAnn data ............................................................................................................................ 9
4.1.4
Video and frame captures .................................................................................................................. 9
4.1.5
Infauna..................................................................................................................................................... 9
Distribution of Seabed Habitats ............................................................................................... 9
4.2.1
4.3
5
5.1
Distribution of sediment features .................................................................................................. 12
Description of habitat distribution ......................................................................................... 15
ANNEX I HABITATS ......................................................................................... 16
Summary Description ............................................................................................................. 16
6
REFERENCES .................................................................................................. 17
7
MAP FOLIO ....................................................................................................... 17
8
OUTPUTS ......................................................................................................... 29
9
APPENDIX 1 ..................................................................................................... 29
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9.1
Grab Positions.......................................................................................................................... 29
9.2
Grab PSA ................................................................................................................................. 30
9.3
Grab Infauna ............................................................................................................................ 31
9.4
Video Positions & Biotopes ..................................................................................................... 40
9.5
Video Sediment Visual Estimates .......................................................................................... 42
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1 Introduction
The primary aim of this report is to provide data from a commissioned survey to be used for the
characterisation of the Annex I Habitat features within selected ‘Areas of Search’, with particular
emphasis on those features for which the area is likely to be designated as a SAC (biogenic reefs and
sandbanks). The survey was part of the process of the acquisition of survey data and preparation of
site specific briefing statements for draft marine SACs. This information will form a contribution to
the knowledge of habitats within the Greater Thames area and complements separate desktop
studies and modelling of the distribution of habitats. The survey work combined acoustic remote
sensing techniques (swath and single beam acoustic ground discrimination) coupled with video and
grab sampling. The area surveyed was selected to fill gaps in the existing knowledge base and to
target areas likely to have Annex I Habitats. This report presents an overview of the survey and its
findings and is supported by Field Survey Reports, a Map Folio and Appendices as well as a GIS
project file, video sequences and frame captures which have been submitted electronically.
The locations of the samples and acoustic survey lines are shown in Map 2 in the Map Folio. The
survey was carried out in July 2007. The strategy adopted for the design of the survey has been to
use existing datasets to model the marine landscape and habitat distribution. An initial model and
review exercise served as a guide to the likely distribution of sandbanks, habitats and existing survey
effort. The survey was carried out in a limited geographic range that included sandbanks within the
survey area, with the purpose of data gathering for an area that was identified from the data review
and modelling exercises.
2 Methodology and analysis
2.1 Interferometric Bathymetric Sidescan Sonar survey
2.1.1
Equipment and deployment
Envision used a GeoAcoustics GeoSwath Plus Interferometric system. This system provides
simultaneous true sidescan sonar and bathymetric data which are geographically coincident and
corrected for tide, vessel movement and position. The data are also corrected for distortion caused
by variations in the speed of sound through water: sound velocity profiles are taken at intervals
through the survey using an Odum SVP transducer lowered to the seafloor. The system gives
sidescan sonar images across a swath 10-12 times water depth as well as swath bathymetry. This
combination of sidescan and swath bathymetry provides complementary information on the physical
nature of the seafloor. For example, the swath data can reveal topographic features (often quite
large) which may be undetected by sidescan sonar and, conversely, sidescan can show seabed
textures resulting from fine-scale sediment features (boulders, sand ripples) that cannot be resolved
by the swath bathymetry.
The system was deployed at a tracking speed of ~10km.hr-1. It was calibrated when first set up on
the vessel and cross tracks were collected during the survey for quality control measures to ensure
data consistency.
2.1.2
Processing
The sidescan from the swath system has a resolution of about 10cm across the swath. This
resolution can be best seen in the ‘waterfall1’ display seen in real-time or in replay mode after post
processing. The waterfall display was observed during the survey, but the survey program permitted
processing in the evenings. Sidescan sonar data were also corrected for vessel movement and the
sonar lines were ‘mosaiced’ to produce sidescan sonar swaths for each acoustic line. This process
1
Waterfall display - A top-down image presentation method where the image pixels for each sonar return
appear at the top of the image and fall downward as they are replaced by each new sonar return at the top
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forms part of the mosaicing operation. However, ‘mosaiced’ images are at a lower resolution than
the raw data as seen in the waterfall displays and have limited value for showing fine-scale texture.
The swath bathymetric data also were processed between survey days and this permitted the
inspection of the bathymetric model (sun-illuminated to reveal small topographic detail). The data
were then gridded to produce bathymetric grids at 5m resolution. The grids were then used to
create a three dimensional terrain model, which was sun-illuminated to highlight the topographic
features. These images were then exported as geotiffs into the survey GIS workspace.
2.2 RoxAnn single beam Acoustic Ground Discrimination System
(AGDS)
2.2.1
Equipment and deployment
An AGDS was run in conjunction with the swath system: it provides useful complementary data on
sediment hardness and roughness and this can aid the interpretation of the sidescan images. It does
not interfere with the swath system and is inexpensive to run. Thus, it is a cost-effective add-on to
any swath survey.
AGDS has the advantage over swath systems in that it is a single-beam system with a vertically
directed signal. This means that no complicated correction has to be made for reflectance or slant
range. It also can measure scatter away from the vertical, which is problematic for swath systems.
Thus, it can measure reflective strength (hardness) and scatter (roughness) quite robustly.
A RoxAnn Groundmaster system was used operating at a frequency of 50kHz. Point values for
hardness, roughness and depth were taken at 2 second intervals as the vessel tracked over the sea.
The data were recorded onto a laptop together with position and time.
2.2.2
Analysis
The AGDS data were cleaned (removal of depth spikes, records when the vessel was stationary and
where there were zero values for depth). The daily data sets were compared using scatter grams
and there appeared to be no obvious shifts in the patterns or overall values between days. This being
the case, it was deemed to be safe to leave the E1 and E2 values as recorded rather than attempt to
standardise on a daily basis. Copies of the daily data sets have been amalgamated in MapInfo ™ to
create a single data set. The data did not undergo further analysis and the hardness and roughness
values were simply displayed over the swath images to aid interpretation.
2.3 Drop-down Video & Grab
2.3.1
Equipment and deployment
Envision used two drop down camera systems during the survey. A small high-resolution CCTV
camera system with integral lighting was used as a rapidly deployed system. The camera housing is
mounted onto a small weighted ‘fish’, which is lowered to the seabed via an umbilical that enables
the underwater image to be viewed in real time on the surface and recorded onto MiniDV tape.
Additionally, a forward directed digital video system mounted in a small frame and controlled from
the surface was used. The system records digitally on a high quality tape in the housing and a back-up
tape in the surface unit. The system was used as a drop-down/short tow system for takes of 2
minutes duration. There are a number of reasons for this deployment strategy; firstly, with drift
towing the tidal currents can quickly carry the sledge so fast that the tape becomes of very limited
use for extracting information during analysis and replay. With a short deployment there is always a
period of slack before the current picks up the system which enables clearer images to be recorded.
Secondly, towing requires a long layback and the position of the sledge becomes very uncertain
(without the aid of sonar positioning systems).
In addition to the video systems, a 0.1m2 Day grab was deployed at sites where a grab sample was
deemed appropriate. Grab samples were taken at selected locations within the survey area, a small
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sample of the sediment was retained for particle size analysis and the remaining sample passed over
a 1mm sieve. The sieved sample was then preserved in a formalin solution for taxonomic
identification.
Positions for sample locations were identified and selected using the acoustic data as the survey
progressed and preliminary results were processed which indicated the various seabed types and
their distribution.
2.3.2
Analysis
Paper notes for the tapes and sediment were recorded during the survey as part of the survey log.
Data were extracted from video tapes by visual inspection during replay and the data entered into a
spreadsheet. In addition, several frames were captured for each sample. These were selected from
periods when the sledge was near stationary, which improved the quality of the captured images.
The main habitat features, conspicuous species or, where this detail was not possible, general
growth forms and higher taxonomic categories were identified and used to assign a biotope category
to each video sample. Species and life forms were assessed on the semi-quantitative SACFOR
system. Visual estimates for percentages of silt, sand, gravel, pebbles, cobbles, boulders and the
features of any bedrock were made for each video sample. Written descriptions have been included
as a summary of the habitat.
The data were matched to a habitat type using a local classification system (Entec/Envision Technical
Note) that can be related to suites of biotopes in the Marine Habitat Description for Britain and
Northern Ireland (MHD) (http://www.jncc.gov.uk/marine/biotopes/) and the records tagged with the
most appropriate habitat type. Any discrete, clear signs of anthropogenic habitat damage seen were
to be recorded (i.e., not widespread and general impression of habitat degradation); but no such
signs were observed.
Grabs samples were passed on to The Institute of Estuarine and Coastal Studies for particle size
analysis and infaunal identification and counts.
3 Data Interpretation
All the above data were incorporated into a GIS system that allowed the datasets to be compared
with each other. In addition to this method the AGDS and grab data were analysed using a
supervised classification using the maximum likelihood classifier, which is generally regarded as the
most satisfactory means of interpreting multispectral data. This process classifies the acoustic data
using signatures developed from the grab sample data, and produced a classified map for the survey
area which was then overlain onto the bathymetric and sidescan sonar mosaic and the boundaries
edited where the higher resolution (sidescan & bathymetric) data suggested more precise
boundaries.
This allowed the analyst to view all data within the survey area and to map the habitat types
suggested by the topography and patterns shown from (1) the sun-illuminated bathymetry; (2) the
sonar reflection of the seabed shown in the sidescan imagery and (3) the AGDS data.
This method allowed the seabed habitats to be mapped for the Margate Sands survey area, and
revealed that the habitats identified are predominantly infaunal with the grab data providing the
detailed biological data. The video footage allowed identification of sediment types but as epifauna
was scarce or very inconspicuous, habitat classification based on epifauna or biotope identification
was difficult or of little use.
The method for the analysis between the datasets and the supporting maps and analysis and overall
assessment has been outlined in Figure 1.
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Figure 1 Scheme for the analysis and interpretation of the data to derive the assessment and distribution of
Annex I Habitats
4 Results of survey
The results are presented as an interpretation of the data in terms of habitat feature characterisation
and biotope distribution. Details of the survey, the equipment used and methods for analysis have
been presented in the field report and are not repeated here in the interests of clarity and
succinctness. A brief summary of the survey is given since this sets out the limitations of the
characterisation possible from the survey data. These limitations are the result of the survey
specifications adhered to by Envision.
Table 1 summarises the survey work and data collected for the survey area.
Table 1 Summary of survey work undertaken for the Area of Search
Area of Survey
Name
THAMES AoS
Margate Sands
Acoustic survey
Interferometric
sidescan &
bathymetry; RoxAnn
AGDS
Video Samples
Grab Samples
75
26
The position of the survey area and location is shown in Map 1 (the maps are presented in a folio
that follows the written sections of the report).
4.1 Summary of result outputs
4.1.1
Swath bathymetry
The raw data within the survey area have been gridded and these data are presented as a sunilluminated image taken from the digital terrain models. The sun-illuminated images are fully georeferenced and are included in the GIS project that accompanies this report. The interpretation of
these images is discussed in Section 3.
4.1.2
Sidescan images
Sidescan images were mosaiced, but the reduction in resolution and dynamic range in the grey scale
of the resulting images made them of limited use for the interpretation of seafloor features. Areas of
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homogeneous seabed and the strength of the returned signal assist with the identification of seabed
types and also confirm the patterns detected by the AGDS and bathymetric data. The sidescan
mosaic is shown in Map 9.
4.1.3
AGDS RoxAnn data
The AGDS data are presented showing roughness and hardness values (Map 10 & Map 11). The
values corresponded well to the seabed features.
4.1.4
Video and frame captures
The video sequences have been transferred to a DVD that accompanies the report. Each sequence is
preceded by its respective video ‘take’ number.
A number of frame captures were taken for each of the video ‘takes’ and these are to be found on
the accompanying CD. The code used to name these frame grabs is the video take number followed
by a sequential frame capture number. All frame captures can be referenced using this numbering
system. The data extracted from the video have been entered into a single spreadsheet which
includes details of sediment types, rock features and species records for each take. This spreadsheet
is to be found on the CD and a summary table of the main data is given in Appendix 1. An overview
of the distribution of sediments and habitats for the survey area is shown in Map 6. Note that due to
limited visibility it was not possible to extract a full suite of data from all samples.
4.1.5
Infauna
The grab data from this field survey have been summarised into habitat categories by Entec as part
of the desktop review of all available infaunal data, and are presented in Map 5.
4.2 Distribution of Seabed Habitats
The habitats have been characterised by their acoustic features as revealed by (1) acoustic hardness
and roughness, (2) digital terrain models (derived from swath bathymetry) and (3) sidescan images.
The acoustic data have been interpreted with reference to the physical seabed habitat features as
determined from the grab data. The video data was used to confirm the distribution of the habitats
types and to add additional information pertaining to the epifauna communities present.
The seabed habitat features that have been used for characterising the acoustic data are presented
Table 2.
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Table 2 Description of the sea bed habitat types and typology used for maps and summary descriptions of the survey areas
Habitat type (broad)
Habitat type (fine)
Possible biotopes
SS.SMu.CSaMu.AfilMysAnit
Epifauna notes
Habitat not sampled with video
SS.SMu.CSaMu.AfilNten
SS.SSA.IMuSa.FfabMag
Moderate diversity polychaete
Moderate diversity fine sands sandy muds
SS.SSA.CFiSa.EpusOborApri
SS.SSA.IFiSa.TbAmPo
SS.SSA.CFiSa.ApriBatPo
Epifauna or Ophiura spp and occasional
Pagurus bernhardus
SS.SSa.OSa
Moderate diversity brittlestars
& bivalves
SS.SSA.IMuSa.SsubNhom
SS.SMu.CSaMu.AfilNten
SS.SSA.IMuSa.FfabMag
Low diversity
polychaete/amphipod
Low diversity sand
SS.SSA.IFiSa.NcirBat
SS.SSA.IMuSa.EcorEns
SS.SCS.ICS.SLan
Very little epifauna, occasional Asterias
rubens and Pagurus bernhardus
SS.SCS.CCS.PomB
SS.SSA.IFiSa.ScupHyd
SS.SSA.IFiSa.NcirBat
Very low diversity sand
Very low diversity
polychaete/amphipod
SS.SCS.CCS.MedLumVen
No obvious epifauna
SS.SSA.CFiSa.EpusOborApri
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Habitat type (broad)
Habitat type (fine)
Page 11 of 43 pages
Possible biotopes
Epifauna notes
SS.SMx.OMx
SS.SMX.OMx.PoVen
Moderate diversity gravel
Moderate diversity fauna in
gravel
SS.SMx.CMx
SS.SCS.ICS.SLan
Often a short hydroid and bryozoans
turf with occasional burrowing
anemones.
SS.SMU.CSaMu.LkorPpel
SS.SCS.ICS.MoeVen
Moderate - high diversity mixed
sediment
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Moderate diversity Sabellaria
SS.SBR.PoR.SspiMx
Very dense Sabellaria
SS.SBR.PoR.SspiMx
Mussel beds
SS.SBR.SMus.ModMx
SS.SBR.SMus.MytSS
Sabellaria spinulosa present but not in
large densities or forming reefs.
Sabellaria spinulosa clumps observed
but very degraded or relic. Other
Habitat not sampled with video
epifauna includes a hydroid and
bryozoans turf. No Reef observed
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4.2.1
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Distribution of sediment features
Figure 2 shows the proportion of sediment types throughout the Margate Sands survey area. It can
be seen from this that the predominant substrate types are sands (77%) and shell gravels (8%) with
some silt/clay (6%), the larger more stable substrates, pebbles (3%) and cobbles(5%), feature
occasionally interspersed within the finer sediments.
BEDROCK
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
Figure 2 Proportion of sediment features within the area surveyed
Map 6 shows the distribution of sediments throughout the area of survey. The samples collected on
the raised sandbank features of ‘Tongue’, ‘Last’ and Margate Sands are predominantly composed of
sand with a small fraction of shell material. In the Queens Channel the sediments become more
influence but must and gravel with occasional pebbles, the deeper regions of the channel have a
significant silt/clay fraction which will influence the communities present.
The gore channel to the south of Margate Sands is the only location within the area of survey which
has a high proportion of cobble present with relatively little sand being present.
Estimates of the proportions of sediment types within each habitat type found in the surveyed area
are shown in Figure 3. These are indicative only, but give a summary of the likely substrate
composition for each of the habitats.
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High diversity brittle stars &
bivalves
BEDROCK
BOULDERS
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
Moderate diversity brittle stars &
bivalves
Moderate diversity polychaete
BEDROCK
BOULDERS
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
Low diversity polychaete/amphipod
with epifauna
BEDROCK
BEDROCK
BOULDERS
BOULDERS
COBBLES
COBBLES
PEBBLES
PEBBLES
GRAVEL
GRAVEL
SAND
SAND
SHELL
SHELL
SILT/CLAY
SILT/CLAY
Very low diversity
polychaete/amphipod
Moderate diversity fauna in gravel
BEDROCK
BOULDERS
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
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BEDROCK
BOULDERS
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
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Mussel beds
Moderate diversity Sabellaria
BEDROCK
BEDROCK
BOULDERS
COBBLES
COBBLES
PEBBLES
PEBBLES
GRAVEL
GRAVEL
SAND
SAND
SHELL
SHELL
SILT/CLAY
SILT/CLAY
Very dense Sabellaria
BEDROCK
BOULDERS
COBBLES
PEBBLES
GRAVEL
SAND
SHELL
SILT/CLAY
Figure 3 Proportion of sediment composition determined from the video and grab records within the
surveyed area
When examining the proportions of sediment within each habitat class the high and moderate
diversity habitats of brittlestars bivalves and polychaetes primarily consist of a sand substrate with
approximately 25% of the substrate made of gravels, silts and cobbles. The lower diversity
polychaetes communities are heavily dominated by sands (up to 90%) with a very small proportion
of other materials but the very low diversity communities do have a pebble component.
The gravel and Sabellaria communities again are sand dominated but do have larger proportions of
gravel, pebbles and shell than brittlestar, bivalve and polychaete habitats. The moderate diversity
Sabellaria habitat contains the largest proportion of shell fragments along with the lowest fraction of
sand.
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4.3 Description of habitat distribution
High diversity brittle stars &
bivalves
Low diversity polychaete/amphipod
with epifauna
Moderate diversity brittle stars &
bivalves
Moderate diversity fauna in gravel
Moderate diversity polychaete
Moderate diversity Sabellaria
Mussel beds
Very dense Sabellaria
Very low diversity
polychaete/amphipod
Figure 4 Proportion of habitat features within the area surveyed
Figure 4 shows the proportions of the habitat types that occur within the Margate Sands survey area.
As expected within an area dominated by sand and sandbanks a typically representative,
impoverished, low diversity habitat of polychaetes and amphipods dominates the area. Despite this,
the area does contain a large proportion of dense Sabellaria habitat, which is atypical of the Greater
Thames AoS. Another community of note is the presence of one grab sample containing Mytilus
edulis in high numbers.
Map 7 shows the distribution of the habitat types throughout the Margate Sands survey area.
The Margate Sands survey area is characterised by sand banks with impoverished infaunal and
epifaunal communities. The troughs and channels between the banks have mixed and gravel
communities with dense populations of Sabellaria spinulosa and brittlestar (Ophiura spp.) dominated
sediments. Although dense aggregations of Sabellaria spinulosa were detected, no reef formations
were observed, but these dense populations of Sabellaria spinulosa were not found elsewhere within
the Greater Thames AoS from the data review exercise.
The area to the south of Margate Hook and into Gore Channel has some boulder and cobbles, with
a faunal turf, present amongst mixed sand and gravel substrate. Here the sediments had high
proportions of Sabellaria. Moving north over the Margate Sand bank and the ‘Last’ the habitats are
impoverished sand with occasional patches of moderate diversity polychaete communities.
The slopes of the sand banks in the area have a more mixed substrate than the peaks and these
substrates are populated by moderate diversity brittlestar and Sabellaria communities. A band of
these habitat types runs along the northern slope of Margate Sands and over the ‘Wedge’ and into
Queens Channel. The remaining area of Queens Channel is a mix of moderate diversity Sabellaria
communities and low diversity polychaetes in the deeper areas. A small area of moderate diversity
fauna in gravel is located within the Queens Channel but is identified from only one sample. As the
channel shallows towards the southern spit of the ‘Tongue’ and moving westwards moderate
diversity Sabellaria spinulosa communities predominate.
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At the northern edge of the site the ‘Tongue’ rises before deepening into the Prices Channel, This
sand bank area is typical of the region in being dominated by low diversity sands populated by
polychaetes and amphipods. There is one patch of high diversity brittle stars & bivalves but again this
is identified from only one grab sample point.
5 Annex I Habitats
5.1
Summary Description
Annex I Sandbanks which are slightly covered by sea water all the times are elevated seabed features
consisting of sandy sediments permanently covered by sea water. Water depth above sandbanks is
seldom more than 20m below chart datum, but some sandbanks may extend into deeper waters.
Sandbanks can be classified topographically (for example, those associated with headlands, the open
shelf or estuary mouths) or by sediment type (for example, gravelly and clean sands, or muddy
sands).
The survey of Margate Sands found possible sand bank features, and these features have a
representative impoverished biological community, which is typical of sandbank features. The
sediments comprising the sand bank are sands at the top of the sand bank feature, with more mixed
and gravelly sands on the slope and edges of the features.
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6 References
2007, Entec & Envision Technical Note. Habitat classification for Wash and Thames
Connor, D.W, Allen, J.H., Golding, N., Howell, K.L., Lieberknecht, L.M., Northern, K.O. & Reker,
J.B. (2004) The Marine Habitat Classification for Britain and Ireland Version 04.05 JNCC,
Peterborough ISBN 1 861 07561 8. (internet version) www.jncc.gov.uk/MarineHabitatClassification
7 Map Folio
Map 1 Margate Sands survey area location and boundary .............................................................................. 18
Map 2 Resulting survey lines and sample locations for the Margate Sands survey area .......................... 19
Map 3 Location of grab samples points with Margate Sands survey area ................................................... 20
Map 4 Location of video samples points with Margate Sands survey area ................................................. 21
Map 5 Habitat types present at each sample location for the Margate Sands survey area ..................... 22
Map 6 Sediment present at each sample location for the Margate Sands survey area ............................ 23
Map 7 Habitat types within the Margate Sands survey area. .......................................................................... 24
Map 8 Sun-illuminated bathymetry for the Margate Sands survey area....................................................... 25
Map 9 Sidescan sonar mosaic for the Margate Sands survey area ................................................................ 26
Map 10 AGDS tracks coloured by E1 (roughness) for the Margate Sands survey area .......................... 27
Map 11 AGDS tracks coloured by E2 (hardness) for the Margate Sands survey area ............................ 28
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Map 1 Margate Sands survey area location and boundary
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Thames AoS: Margate Sands Survey Report
Page 19 of 43 pages
Map 2 Resulting survey lines and sample locations for the Margate Sands survey area
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February 2016
Thames AoS: Margate Sands Survey Report
Page 20 of 43 pages
Map 3 Location of grab samples points within Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 21 of 43 pages
Map 4 Location of video samples points within Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 22 of 43 pages
Map 5 Habitat types present at each sample location for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 23 of 43 pages
Map 6 Sediment present at each sample location for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 24 of 43 pages
Map 7 Habitat types within the Margate Sands survey area.
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 25 of 43 pages
Map 8 Sun-illuminated bathymetry for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 26 of 43 pages
Map 9 Sidescan sonar mosaic for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 27 of 43 pages
Map 10 AGDS tracks coloured by E1 (roughness) for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 28 of 43 pages
Map 11 AGDS tracks coloured by E2 (hardness) for the Margate Sands survey area
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 29 of 43 pages
8 Outputs
Accompanying this report are several outputs, which are delivered on other media.
OUTPUT
MEDIA
Edited DVD of video footage
2 DVDs
Bathymetric grid in surfer format
DATA DVD
Bathymetric gird as Geotiffs
DATA DVD
Sidescan Sonar Mosaic as GeoTiffs
DATA DVD
GIS project as a MapInfo™ workspace & files GIS CD
Digital frame captures from video footage.
DATA CD
Data extracted from video footage
DATA CD
Raw AGDS Data
DATA CD
9 Appendix 1
9.1 Grab Positions
SURVEY
AREA
ID
LONGITUDE
LATITUDE
HABITAT CLASS
1
1.25156
51.4849
Margate Sands
High diversity brittle stars & bivalves
2
1.28449
51.4841
Margate Sands
Low diversity polychaete/amphipod with epifauna
3
1.2795
51.4773
Margate Sands
Low diversity polychaete/amphipod with epifauna
4
1.2747
51.4746
Margate Sands
Low diversity polychaete/amphipod with epifauna
5
1.26893
51.4717
Margate Sands
Moderate diversity polychaete
6
1.24959
51.465
Margate Sands
Very dense Sabellaria
7
1.26165
51.4643
Margate Sands
Very dense Sabellaria
8
1.26851
51.4645
Margate Sands
Moderate diversity Sabellaria
9
1.27851
51.466
Margate Sands
Moderate diversity brittle stars & bivalves
10
1.28637
51.4641
Margate Sands
Moderate diversity Sabellaria
11
1.28549
51.4618
Margate Sands
Very dense Sabellaria
12
1.27918
51.4597
Margate Sands
Moderate diversity fauna in gravel
13
1.26392
51.4582
Margate Sands
Moderate diversity brittle stars & bivalves
14
1.27071
51.4536
Margate Sands
Low diversity polychaete/amphipod with epifauna
15
1.28848
51.4469
Margate Sands
Very dense Sabellaria
16
1.27387
51.4426
Margate Sands
Moderate diversity Sabellaria
17
1.26811
51.4471
Margate Sands
Very dense Sabellaria
18
1.26268
51.4366
Margate Sands
Moderate diversity brittle stars & bivalves
19
1.25169
51.4399
Margate Sands
Moderate diversity brittle stars & bivalves
20
1.25179
51.4436
Margate Sands
Mussel beds
21
1.25415
51.4299
Margate Sands
Low diversity polychaete/amphipod with epifauna
22
1.25176
51.4251
Margate Sands
Moderate diversity polychaete
23
1.27249
51.4248
Margate Sands
Very low diversity polychaete/amphipod
24
1.2919
51.414
Margate Sands
Low diversity polychaete/amphipod
25
1.25424
51.3981
Margate Sands
Low diversity polychaete/amphipod with epifauna
26
1.24661
51.3979
Margate Sands
Low diversity polychaete/amphipod with epifauna
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 30 of 43 pages
9.2 Grab PSA
Sample
Gravel
Granule
Site/Take
+4mm
2-4 mm
1
4.63
0.02
V. coarse
sand
1000-2000
µm
1.79
2
0
0
0
3
0
0
0
4
0
0
0
5
0
0
0
6
48.41
10.43
7
54.48
8
0.3
Coarse sand
Medium
Fine sand V. fine sand
sand
500-1000 µm 250-500 µm 125-250 µm 63-125 µm
2.99
Silt & clay
<63 µm
21.07
31.14
22.74
15.18
0
1.9
26.44
33.79
37.87
2.6
54.59
37.12
0.32
5.37
0.94
44.97
48.37
1.19
4.55
0.8
18.48
33.48
18.58
28.67
7.49
2.81
6.12
8.42
6.94
8.06
11.28
8.13
1.98
1.08
1.83
2.98
17.72
1.51
0
0.1
2.45
12.79
24.61
58.55
9
0
0
0
0.25
4.62
26.25
32.44
36.44
10
3.61
2.96
2.94
2.82
11.44
25.95
22.75
27.54
11
6.07
4.59
1.28
5
6.26
21.77
26.31
28.41
12
7.12
1.93
2.52
10.45
23.58
29.33
10.89
13.78
13
0
0
0
0
1.88
24.9
31.65
41.58
14
0
0
2.99
0.77
5.93
49.08
28.52
12.73
15
15.43
10.11
4.82
2.64
3.27
16.75
22.06
24.11
16
15.56
8.35
7.54
2.31
3.74
10.41
12.19
39.31
17
21.16
9.5
4.14
6.56
16.27
18.78
12.14
10.92
18
1.32
1.92
0.29
1.78
11.89
31.8
22.63
28.37
19
4.74
0.49
0.92
1.29
4.58
18.38
20.74
48.16
20
7.61
2.72
6.65
16.24
50.85
9.94
0.66
4.6
21
0
1.03
1.46
15.3
45.52
30.61
1.89
4.2
22
0.03
4.07
3.94
18.81
51.41
16.55
0.02
5.17
23
0
0
0
5.8
67.88
26.31
0.01
0
24
0
0
0.54
3.05
35.76
47.38
7.6
5.68
25
0
0
0.21
4.46
30.16
39.27
12.46
13.44
26
0
0
0
1.29
16.2
33.43
20.95
28.13
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
Page 31 of 43 pages
9.3 Grab Infauna
Taxon
1
2
3
4
5
6
7
8
9
10
11
Eucheilota maculata
12
13
P
Lovenella clausa
P
Calycella syringa
P
15
16
17
18
19
20
P
P
21
22
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
Clytia hemisphaerica
P
Clytia paulensis
P
P
Obelia dichotoma
P
ANTHOZOA
2
P
P
P
P
P
P
P
20
420
1
P
3
P
P
P
P
P
P
Obelia bidentata
P
P
27
P
P
P
P
P
P
P
P
P
26
P
P
P
P
P
P
P
P
164
78
13
P
P
6
1
P
3
1
PLATYHELMINTHES
NEMERTEA
3
NEMATODA
9
1
8
1
1
9
1
5
5
1
1
Golfingia elongata
3
1
5
15
7
3
5
2
1
2
1
1
2
2
Hermonia hystrix
1
1
Gattyana cirrosa
1
4
13
Malmgreniella arenicolae
1
5
23
9
1
1
4
1
8
2
2
1
Malmgreniella marphysae
1
Lepidonotus squamatus
2
Envision Mapping Ltd.
P
P
P
Cerianthus lloydii
Pholoe baltica
25
P
Clytia gracilis
Harmothoe sp.
24
P
Sertularella gaudichaudi
Sertularia argentea
23
P
Halecium sp.
Hydrallmania falcata
14
2
3
1
3
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 32 of 43 pages
4
5
6
7
8
9
Pholoe inornata
Sthenelais boa
3
Eteone flava/ longa
16
10
11
1
5
3
2
12
13
14
15
16
17
18
19
13
2
7
1
3
21
22
23
24
1
1
Anaitides mucosa
4
Anaitides rosea
1
Eulalia ornata
2
3
1
Eumida bahusiensis
6
4
1
5
Eumida sanguinea
4
1
1
2
2
83
28
13
16
1
5
Glycera (juv.)
2
2
2
1
1
1
3
2
1
1
1
1
Glycera tridactyla
3
Glycinde nordmanni
1
1
1
1
1
Podarkeopsis capensis
1
1
1
1
1
1
3
6
1
1
1
2
Microphthalmus similis
1
Eusyllis blomstrandi
2
4
Streptosyllis websteri
1
Syllides japonica
1
Exogone naidina
1
Sphaerosyllis hystrix/taylori
Autolytus sp.
1
4
Nereis longissima
Nephtys (juv.)
Nephtys assimilis
Envision Mapping Ltd.
26
1
Anaitides longipes
Goniada maculata
25
1
Mysta barbata
Glycera alba
20
1
11
4
4
4
8
3
7
2
6
5
1
2
1
4
3
9
2
1
2
1
5
8
5
1
2
6
7
3
3
1
1
1
7
1
3
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 33 of 43 pages
4
5
6
7
8
9
10
11
Nephtys caeca
12
13
14
16
17
3
Nephtys cirrosa
6
Nephtys hombergii
3
18
19
1
4
6
11
4
3
3
2
1
7
7
1
1
3
4
26
5
Protodorvillea kefesteini
Scoloplos armiger
20
21
22
23
1
14
3
1
1
8
2
3
1
1
1
6
Dipolydora (Polydora) caeca
1
Polydora cornuta
32
5
1
2
1
1
1
1
Pygospio elegans
1
1
Dipolydora (Polydora) flava
1
3
1
4
1
6
1
1
2
1
2
1
5
1
4
3
2
Spio martinensis
2
55
Magelona johnstoni
5
1
35
1
2
9
33
17
1
222
42
6
1
5
Aphelochaeta marioni
2
Chaetozone (Caulleriella) zetlandica
1
82
3
24
1
1
1
4
2
1
2
10
1
7
4
22
7
1
4
2
2
1
1
1
Tharyx sp. A
Envision Mapping Ltd.
34
3
1
Caulleriella alata
Capitella capitata sp. (agg)
1
1
Spio decorata
Flabelligerra affinis
6
1
Scolelepis bonnieri
Chaetozone christiei
26
3
Aonides oxycephala
Spiophanes bombyx
25
6
Aricidea minuta
Pseudopolydora pulchra
24
1
Nephtys kersivalensis
Lumbrineris gracilis
15
1
1
1
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 34 of 43 pages
4
5
6
7
Mediomastus fragilis
3
Notomastus sp.
1
8
9
5
10
11
12
2
2
1
5
1
Euclymene oerstedii
13
14
15
16
16
3
12
7
2
Ophelia borealis
1
2
6
22
23
24
1
25
26
8
4
2
1
1
2
8
2
2
Lagis koreni
48
5
30
Sabellaria spinulosa
3
3223
Ampharete lindstroemi
2
Lanice conchilega
102
16
3
30
329
2
7
35
114
32
2
10
40
21
3
22
79
34
15
155
54
22
2
402
128
1
127
3404
86
749
199
3051
56
3
8
7
8
4
5
8
3
6
1
38
41
36
7
39
1
6
7
9
9
23
1
5
2
208
72
30
Nicolea venustula
1
Polycirrus sp.
6
3
Sabella pavonina
23
2
Pomatoceros lamarcki
1
1
5
1
1
1
Tubificoides cf. galiciensis
2
Achelia echinata
1
Anoplodactylus petiolatus
7
5
41
1
2
1
1
3
1
Anoplodactylus pygmaeus
34
2
1
4
8
1
14
1
10
Nymphon brevirostre
1
2
1
3
1
3
30
3
1
1
2
3
1
15
2
3
3
1
1
1
Elminius modestus
Envision Mapping Ltd.
3
21
1
Owenia fusiformis
OSTRACODA
1
20
3
Galathowenia oculata
COPEPODA
19
3
Scalibregma inflatum
Balanus improvisus
18
1
Scalibregma celticum
Limnodriloides
17
2
7
25
4
1
1
1
6
7
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 35 of 43 pages
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Eusarsiella zostericola
Gastrosaccus spinifer
1
1
6
18
19
1
1
1
20
21
3
Schistomysis kervillei
22
23
24
1
1
1
1
Perioculodes longimanus
1
1
1
1
1
5
Iphimedia nexa
1
Atylus falcatus
1
1
1
Atylus guttatus
1
1
Atylus swammerdamei
1
1
Ampelisca brevicornis
4
Ampelisca diadema
1
Ampelisca spinipes
1
4
1
1
2
5
10
2
17
Ampelisca tenuicornis
26
6
1
1
1
Bathyporeia elegans
1
12
4
1
8
Bathyporeia guilliamsoniana
1
3
2
Cheirocratus intermedius
1
4
9
1
5
1
1
1
1
1
1
5
3
6
1
Microprotopus maculatus
1
1
2
1
Gammaropsis cornuta
30
1
47
Ericthonius punctatus
Envision Mapping Ltd.
2
1
Cheirocratus sp. (female)
Aora gracilis
3
23
Bathyporeia pelagica
Photis longicaudata
1
3
Urothoe brevicornis
Abludomelita obtusata
26
1
Pontocrates altamarinus
Amphilochus neapolitanus
25
5
1
6
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 36 of 43 pages
4
5
6
7
8
9
10
11
12
13
14
15
Corophium sextonae
3
Unciola crenatipalma
19
16
17
18
19
1
2
DECAPODA (Megalopa)
1
2
DECAPODA (Zoea)
1
26
1
1
1
2
1
Pandalina brevirostris
1
Crangon allmanni
1
1
Crangon crangon
1
Crangon bispinosus
1
1
1
Crangon trispinosus
1
1
Anapagurus laevis
1
1
1
Galathea intermedia
1
Pisidia longicornis
1
5
2
Pirimela denticulata
3
4
1
3
4
13
1
2
1
5
1
1
58
12
1
1
1
2
1
2
2
6
1
2
1
1
1
1
1
2
Liocarcinus depurator
Envision Mapping Ltd.
3
1
Eualus pusiolus (juv.)
Liocarcinus pusillus
25
1
Diastylis bradyi
Liocarcinus holsatus
24
1
Pseudocuma gilsoni
Liocarcinus arcuatus
23
1
Bodotria scorpioides
Liocarcinus sp. (juv.)
22
1
Tanaopsis graciloides
Achaeus cranchii
21
4
Pariambus typicus
Pagurus bernhardus
20
1
1
2
1
1
3
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 37 of 43 pages
4
5
6
7
8
9
10
11
12
13
14
Necora puber
15
16
17
18
3
1
19
21
22
23
24
25
26
1
3
1
1
Crepidula fornicata
2
1
Polinices pulchellus
1
2
Hinia (juv.)
1
1
Turbonilla
2
Dendronotus frondosus
1
4
2
Doto
4
Acanthodoris pilosa
5
Aeolidiidae (juv.)
11
Nucula nucleus
1
Mytilus edulis
31
1
4
2
3
6
135
17
1
1
1
25
82
Aequipecten opercularis
Mysella bidentata
20
6
1
1
21
6
51
1
3
5
148
2
1
8
9
1
15
1
1
2
4
1
2
Cerastoderma edule
Mactra stultorum
4
83
1
1
Spisula solida
1
5
Spisula subtruncata
2
1
Lutraria lutraria (juv.)
1
Ensis americanus
1
1
2
8
166
3
2
3
71
354
2
Ensis arcuatus
1
10
2
4
2
Ensis ensis
Fabulina fabula
1
1
1
Macoma balthica
Abra alba
2
1
1
1
1
6
1
1
10
7
3
8
1
12
1
1
1
Timoclea ovata
Tapetinae (juv.)
Envision Mapping Ltd.
1
7
25
3
1
3
1
1
1
1
1
7
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 38 of 43 pages
4
5
6
7
8
9
10
11
12
13
14
Mya truncata
15
16
18
P
P
P
Alcyonidium mytili
P
P
P
P
P
P
24
25
26
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
Conopeum reticulum
P
P
P
P
P
Electra monostachys
P
P
P
P
P
Electra pilosa
P
P
P
P
Aspidelectra melolontha
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
Bicellariella ciliata
P
Phoronis
2
ASTEROIDEA (juv.)
7
3
5
2
2
9
P
P
6
4
Ophiothrix fragilis
1
1
Acrocnida (Amphiura) branchiata
1
Amphipholis squamata
1
1
Ophiura albida
3
Ophiura ophiura
2
ECHINOIDEA (juv.)
2
Psammechinus miliaris
1
Envision Mapping Ltd.
23
P
Bowerbankia
Ophiuridae (juv.)
22
P
Anguinella palmata
Amphiuridae (juv.)
21
31
Alcyonidium diaphanum
Bugula plumosa
20
3
Saxicavella jeffreysi
Vesicularia spinosa
19
1
Corbula gibba
Alcyonidium parasiticum
17
1
4
1
9
2
7
3
3
6
2
1
February 2016
Thames AoS: Margate Sands Survey Report
Taxon
1
2
3
Page 39 of 43 pages
4
5
6
7
8
Echinocardium cordatum
9
10
11
12
5
13
14
15
16
17
165
18
19
20
21
22
23
24
25
26
8
Pelonaia corrugata
1
Molgula sp.
2
102
12
11
1
1
1
Total quantitative abundance
197
25
20
12
15
3358
1193
282
375
343
3624
464
685
26
1547
537
4075
859
280
258
41
53
6
81
16
28
Total quantitative species
29
7
4
7
12
35
47
28
21
42
50
37
25
9
71
49
71
49
53
40
12
20
4
16
6
11
Total colonial species
12
3
3
3
6
6
6
6
8
5
8
9
5
4
8
10
14
10
10
10
3
3
0
1
7
4
Total species
41
10
7
10
18
41
53
34
29
47
58
46
30
13
79
59
85
59
63
50
15
23
4
17
13
15
Envision Mapping Ltd.
February 2016
Thames AoS: Margate Sands Survey Report
9.4 Video Positions & Biotopes
TAKE
SURVEY AREA
DEPTH (m)
LONGITUDE
(WGS84)
LATITUDE
(WGS84)
HABITAT TYPE
1
MARGATE SANDS
20
51.4848
1.25111
No visible data
2
MARGATE SANDS
16
51.4841
1.2851
No visible data
3
MARGATE SANDS
11
51.4772
1.2795
No visible data
4
MARGATE SANDS
7
51.4745
1.27513
No visible data
5
MARGATE SANDS
8
51.4715
1.26813
SAND
6
MARGATE SANDS
10
51.4649
1.25044
No visible data
7
MARGATE SANDS
11
51.4642
1.2617
SAND WITH GRAVEL/PEBBLES
8
MARGATE SANDS
13
51.4649
1.26865
SAND WITH GRAVEL/PEBBLES
9
MARGATE SANDS
17
51.4662
1.27834
No visible data
10
MARGATE SANDS
21
51.464
1.2853
SAND WITH GRAVEL/PEBBLES
11
MARGATE SANDS
22
51.4616
1.28557
SAND WITH GRAVEL/PEBBLES
12
MARGATE SANDS
22
51.4596
1.27812
PEBBLES & SAND WITH GRAVEL
13
MARGATE SANDS
19
51.4578
1.26293
PEBBLES & SAND WITH GRAVEL
14
MARGATE SANDS
19
51.4535
1.27098
SAND WITH PEBBLES
15
MARGATE SANDS
10
51.447
1.28771
PEBBLES & SAND WITH GRAVEL
16
MARGATE SANDS
14
51.4428
1.27361
SAND & PEBBLES/GRAVEL/COBBLES
17
MARGATE SANDS
8
51.4469
1.26829
SAND WITH PEBBLES
18
MARGATE SANDS
15
51.4375
1.26273
No visible data
19
MARGATE SANDS
12
51.4399
1.25103
SAND
20
MARGATE SANDS
8
51.4436
1.25236
SAND WITH PEBBLES/COBBLES
21
MARGATE SANDS
5
51.4296
1.25496
SAND
22
MARGATE SANDS
4
51.4253
1.25216
SAND
23
MARGATE SANDS
5
51.4249
1.27278
SAND
24
MARGATE SANDS
4
51.414
1.29223
SAND
25
MARGATE SANDS
10
51.3959
1.27427
COBBLES
26
MARGATE SANDS
15
51.3975
1.25388
SAND
27
MARGATE SANDS
12
51.3979
1.24605
SAND
28
MARGATE SANDS
10
51.3954
1.25094
SAND
29
MARGATE SANDS
13
51.3971
1.26886
SAND WITH PEBBLES
30
MARGATE SANDS
10
51.396
1.27466
COBBLES WITH SAND
31
MARGATE SANDS
10
51.3973
1.27811
COBBLES WITH SAND
32
MARGATE SANDS
8
51.3967
1.28852
COBBLES WITH SAND
33
MARGATE SANDS
4
51.4244
1.27259
SAND
34
MARGATE SANDS
7
51.4256
1.24703
SAND
35
MARGATE SANDS
6
51.4279
1.25795
SAND
36
MARGATE SANDS
4
51.4335
1.27311
SAND
37
MARGATE SANDS
14
51.4354
1.25486
SAND
38
MARGATE SANDS
13
51.4373
1.2642
SAND
39
MARGATE SANDS
13
51.4391
1.25839
SAND WITH SHELL
40
MARGATE SANDS
13
51.4401
1.25372
SAND WITH SHELL
41
MARGATE SANDS
16
51.4404
1.27429
SAND WITH GRAVEL/SHELL
42
MARGATE SANDS
7
51.4407
1.28224
SAND WITH COBBLES
43
MARGATE SANDS
12
51.4433
1.27821
GRAVEL WITH SAND
44
MARGATE SANDS
15
51.4445
1.27304
SAND WITH GRAVEL
45
MARGATE SANDS
13
51.446
1.28416
SAND WITH GRAVEL
Envision Mapping Ltd.
Thames AoS: Margate Sands Survey Report
TAKE
SURVEY AREA
DEPTH (m)
LONGITUDE
(WGS84)
LATITUDE
(WGS84)
HABITAT TYPE
46
MARGATE SANDS
11
51.4483
1.28384
SAND WITH GRAVEL
47
MARGATE SANDS
8
51.4469
1.26817
SAND WITH GRAVEL
48
MARGATE SANDS
11
51.4494
1.26894
SAND
49
MARGATE SANDS
15
51.4519
1.26919
SAND
50
MARGATE SANDS
14
51.4501
1.25166
SAND WITH SHELL
51
MARGATE SANDS
14
51.4527
1.25366
SAND WITH SHELL/GRAVEL
52
MARGATE SANDS
15
51.454
1.2564
SAND WITH SHELL
53
MARGATE SANDS
19
51.4581
1.26414
SAND WITH SHELL
54
MARGATE SANDS
19
51.4598
1.26534
SAND
55
MARGATE SANDS
17
51.46
1.25606
SAND WITH COBBLES
56
MARGATE SANDS
13
51.4614
1.24994
SAND WITH GRAVEL
57
MARGATE SANDS
22
51.4604
1.28074
SAND WITH GRAVEL
58
MARGATE SANDS
21
51.4645
1.28819
SAND WITH GRAVEL
59
MARGATE SANDS
19
51.4676
1.28416
No visible data
60
MARGATE SANDS
16
51.4658
1.27624
SAND WITH GRAVEL/COBBLES
61
MARGATE SANDS
13
51.4639
1.26792
SAND AND GRAVEL/COBBLES
62
MARGATE SANDS
16
51.4676
1.26901
SAND
63
MARGATE SANDS
11
51.4642
1.25618
SAND WITH PEBBLES
64
MARGATE SANDS
15
51.4678
1.25628
SAND
65
MARGATE SANDS
5
51.4734
1.25757
SAND
66
MARGATE SANDS
17
51.4806
1.26136
SAND
67
MARGATE SANDS
20
51.4852
1.25044
SAND WITH PEBBLES
68
MARGATE SANDS
22
51.4841
1.24854
SAND
69
MARGATE SANDS
14
51.4791
1.24887
SAND WITH GRAVEL
70
MARGATE SANDS
21
51.4857
1.27566
SAND
71
MARGATE SANDS
16
51.4837
1.28231
SAND
72
MARGATE SANDS
12
51.4785
1.28544
SAND
73
MARGATE SANDS
10
51.4771
1.27966
SAND
74
MARGATE SANDS
5
51.4754
1.28485
SAND
75
MARGATE SANDS
13
51.4722
1.28383
SAND
76
MARGATE SANDS
20
51.4848
1.25111
No visible data
Envision Mapping Ltd.
Thames AoS: Margate Sands Survey Report
Page 42 of 43 pages
SHELL
SAND
GRAVEL
PEBBLES
COBBLES
BOULDERS
TAKE
BEDROCK
9.5 Video Sediment Visual Estimates
1
2
3
4
5
5
95
6
7
20
20
60
8
10
10
80
9
10
5
10
20
65
11
5
10
10
75
12
5
50
10
35
13
50
10
40
14
10
90
15
5
40
10
45
16
10
25
10
55
17
5
10
85
18
19
5
20
5
95
5
21
100
22
5
23
95
100
24
25
90
100
100
26
100
27
100
28
100
29
10
90
30
90
10
31
90
10
33
90
10
34
100
35
98
2
36
98
2
37
98
2
38
95
5
39
95
5
40
90
10
Envision Mapping Ltd.
February 2016
41
42
43
10
3
12
SHELL
85
15
85
5
85
44
45
46
SAND
GRAVEL
PEBBLES
Page 43 of 43 pages
COBBLES
BOULDERS
TAKE
BEDROCK
Thames AoS: Margate Sands Survey Report
5
60
40
30
70
10
85
47
5
10
80
5
48
5
10
80
5
49
100
50
100
51
85
15
75
15
70
30
54
95
5
55
100
52
10
53
56
10
90
57
25
75
58
25
75
59
20
80
80
60
61
10
10
62
40
40
63
64
50
100
10
80
65
100
66
100
67
5
95
68
20
80
69
100
70
10
90
71
100
72
80
73
5
95
74
100
75
100
76
100
Envision Mapping Ltd.
10
February 2016