Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
Monitoring
Background
Currently there is no strategic monitoring carried out in Cardigan Bay by the Cardigan Bay Coastal
Group although members of the Group – particularly the three Local Authorities, do individually
carry out monitoring working to known parameters. Other Group members who already have a more
strategic remit do carry out monitoring on a more strategic basis.
The Group has however now agreed that they will carry out monitoring on a Bay-wide or even a
regional basis and this will be developed during the meetings throughout the next 12 months and will
be reported upon in the next Overview.
Current position
Monitoring in the Group’s area has been carried out by the following organisations in the2001 / 2002
year ending on 31 March 2002: 
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Gwynedd Council
Ceredigion County Council
Pembrokeshire County Council
Environment Agency
Railtrack
Whilst further details of the outputs can be obtained from these organisations direct via their web sites
and indeed either direct or via links from our own Cardigan Bay Coastal Group web site, the
following gives a more general overview of the work carried out in the 6th Overview year by those
organisations actively carrying out monitoring.
Gwynedd Council
Current and Future Monitoring regime
Beach Profiles
Currently beach profile data is captured on a strategic level at 1km intervals. For open coast situations
this would appear to provide an acceptable data set to carry out analysis, which is representative for
the length of coastline in question. The analysis can provide data on tidal contour offsets, beach
gradients and cross-sectional areas below the beach profile and tidal contours if necessary.
It is suggested in the Beach Management Manual (BMM) - CIRIA Report 153 - that beach profiles on
groyned beaches should be surveyed on both sides of each groyne and in the centre of the bays. It also
suggests that it would be beneficial to survey longitudinal sections along the toe of the structure to
monitor scouring. Whilst it is possible to survey a fixed longitudinal profile against a vertical
structure where the line of the profile does not change, it is not practical when a structure is fronted
by a stepped or sloping revetment because the profile line moves horizontally as the beach level rise
or fall.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
Gwynedd Council have a kinematic (real time) differential global positioning system (DGPS) which
presents many more options for data capture. The best method of monitoring beaches fronting
structures, with or without groynes, is by topographic survey. With topographic data the beach can be
modelled and will provide, over time, the following
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more accurate sediment volumes
tidal contours along the whole frontage
tidal contour offset analysis at any point along the frontage
toe scour data
beach gradients at any point along the frontage
maximum and minimum beach levels along the frontage
base datum for Post Project Appraisal monitoring
Topographic surveys will provide considerably more information but will also cost more to capture.
To mitigate this the conventional beach profiles will no longer be surveyed along structure frontages.
The BMM recommends beach profiles be surveyed on both sides of each groyne and in the centre of
each bay. For Tywyn, with 30 groynes, this adds up to 69 profiles whilst at present only 3 sections are
surveyed.
Marsh Edge Surveys
Salt marshes develop as the upper mudflats build higher with fresh accumulations of fine sediment so
the number and duration of tidal flooding decreases. At a critical point in this upward growth the
mudflat becomes exposed for long enough each day to allow vegetation to colonise. Marsh surfaces
are therefore much higher, relative to mean tide level, than mudflats and consequently are flooded
much less frequently, in most cases only by the highest spring tide. The interface between mudflats
and salt marshes are often marked by a small cliff, which can be up to a metre high and marsh
accretion is balanced by erosion. Shifts in the position of estuarine channels or sea level changes can
alter the position of these cliffs (Pethick 1984).
At present the only monitoring carried out within estuaries are marsh edge surveys, which are carried
out annually. No analysis of this survey data has been carried out to date because the data set is still
small. Analysis can determine:  Areas of salt marsh
 Movement of the salt marsh edge cliff
This analysis could also be carried out using information supplied by rectified digital vertical aerial
photography flown at low water.
Hydrographic Surveys
Annual hydrographic surveying of the Dyfi, Mawddach and Glaslyn/Dwyryd estuaries has the
potential to establish the following:  Sedimentation rates
 Channel migrations
As identified previously channel migration can cause erosion of salt marshes, which are often the first
line of defence. Having both sets of data will enable cause and effect to be identified.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
Beach Inspections
There has not been a Ground Shoreline Inspection of the Meirionnydd coastline since 1990 and South
Lleyn since 1996. It is therefore proposed to undertake these inspections prior to the next SMP
review.
High Level Target 7C requires an annual coastal erosion risk assessment to include actions taken or
proposed, the report to be presented to the Coastal Group. Again there is significant additional work
involved with carrying out this assessment. A base risk assessment needs to be carried out of all
potential erosion areas and this could be included with the Ground Shoreline Inspections.
Sediment Sampling
The whole of North Cardigan Bay was sampled in 1997 and it is therefore proposed to sample the
entire Gwynedd coastline currently covered by beach profiles.
Inshore Wave Monitoring
In the Cardigan Bay area, it is proposed to reduce the existing 9 installations to 8. As the remaining
capture windows become less it is increasingly difficult to estimate how many events will be captured
annually and hence what the cost will be.
Analysis
There appears to be little guidance to be had regarding analysis. Clearly it is not worthwhile carrying
out analysis of data until the data set is sufficiently large to be able to provide information regarding
underlying trends. It is proposed to carry out analysis on the following:  Beach profiles
 Marsh edge
 Inshore wave monitoring
Conclusions
1. Suitably accurate GPS surveying equipment has allowed large-scale topographic and
hydrographic surveys to be carried out which has presented more options for capturing data.
2. Having considered the beach profiles undertaken to date, it has been concluded that better data
can be produced, particularly for future design work, by carrying out comprehensive
topographic surveys along defended frontages.
3. In an attempt to try and improve our understanding of estuaries annual hydrographic surveys
are proposed for the three main estuaries.
The commissioning of rectified digital vertical aerial photography flown at low water at a frequency
of once every five years would be very beneficial and it is hoped that this can be pursued through the
Cardigan Bay Coastal Group with contributions from all interested parties.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
2001/2002 Report
Shoreline monitoring work during the year in question was somewhat reduced due mainly to the
advent of Foot and Mouth desease which restricted access to the estuaries and foreshore. However the
following is a report on activities during this period: 
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Beach profiles carried out Spring & Autumn in positions shown on plan. There are currently
96 permanent stations between Aberdyfi and Pontllyfni. They are numbered 1 to 86 in
Cardigan Bay with stations 81,82 and 83 being redundant. The work is either carried out inhouse or by Contractors who have to work to a strict ever-evolving specification.
Inshore wave monitoring was not carried out this year as no opportunities have presented
themselves to complete the matrix of events. It should be appreciated that more common
events can be accommodated early in any monitoring programme whilst it is far more difficult
to complete the final more obscure parts of the matrix due to a number of interconnected
factors.
No marsh edge monitoring was undertaken, mainly because of the foot and mouth epidemic.
No survey work – aerial, bathymetric or LIDAR based, was carried out in the year.
Ceredigion County Council
Annual Report
As part of a coastal monitoring programme, Ceredigion County Council annually undertake
topographic surveys and profile surveys along the Ceredigion coastline. This is the seventh year that
the 42-profile survey has been undertaken at 12 locations along the coast with earlier surveys being
restricted to the Aberystwyth frontage alone. Included in this examination of the coast are three
topographical surveys:  Pen-yr-Ergyd, at the mouth of the Teifi Estuary;
 Borth frontage; and
 Tan-y-Bwlch.
The locations of the surveys can be seen in Figures: 1 2 3 4 5 6 7
This report provides a summary of the major changes that have occurred during the period of
monitoring, with particular attention paid to those changes occurring over the period between August
2000 and 2001. The data gathered so far is providing invaluable information, especially with regard
to the short-term trends in beach response. This is already assisting in the management of the
coastline. Long-term trends in the beach profiles are emerging but there still needs to be some
caution when attempting to predict future changes.
A discussion of the beaches is given by area from south to north in Section 2. The changes are
graphically illustrated using:
 Profile plots of beach level against chainage.
 Beach trends that show accretion/erosion trends since the respective datum year of each
profile.
 Topographic surveys
Later sections provide both an overview of the behaviour of the coast and also the main concerns.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
As in the last few years, the North and South beaches at Aberaeron will be examined separately as
these beaches respond independently of each other. Thus, the profiles described as Aberaeron 1 to 5,
prior to the 1998-9 survey report, have now been split into South Beach 1 and 2, and North Beach 1
to 3, respectively.
Discussion
This section discusses changes that have been noted in the beaches for each specified location
following this year’s survey. This analyses, as appropriate, changes in beach profiles and topographic
surveys and studies the beach trends. The results are illustrated using the following methods:
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Beach profiles for this year are superimposed upon an envelope of previous profiles. This
demonstrates how high or how low the beach has been, based on all of the previous
monitoring data. The 2000 profile has also been included to provide a short-term comparison
to the 2001 profile. The Highest Astronomical Tide (HAT), Mean High Water Spring
(MHWS) and Mean Sea Level (MSL) has also been shown as guidance for considering the
beach response to wave action.
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Trends for each profile have been plotted to show the pattern of erosion and/or accretion over
previous years. The graphs plot the distance from the intersection of the beach at various
water levels to a datum position, generally defined as the position of the beach in the first year
data was taken. The distance of the intersection point from datum is plotted positive to
indicate accretion or negative to indicate erosion. A discussion of the resulting trends is
included later in this section.
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A topographic survey approach allows a more comprehensive view to be taken of the
behaviour of the beach, which can be compared with previous years data and presented
graphically, showing contours of areas of accretion and erosion on a ‘plan view’. Both the
Pen-yr-Ergyd spit and the Borth frontage have been surveyed topographically since 1995,
while the Tan-y-Bwlch frontage has been undertaken since 1999.
Generally three plots have been included for each location that has been surveyed
topographically:
 Contour plot of 2001 survey at 0.5m contour intervals.
 Changes between the most recent survey (2001) and last years survey (2000) at 0.25m contour
intervals. For this plot erosion or accretion colours in the region of survey inaccuracy, between
+0.25m and 0.25m, have been removed.
 Changes between the most recent survey (2001) and the oldest survey (either 1995 or 1999) at
0.5m contour intervals.
 In addition, cross-sections, from the topographic plot, have been taken of the Pen-yr-Ergyd spit
at strategic locations to show how the spit has changed since 1995 at these points.
Comments from monitoring reports since 1998 are included in this section so that a comparison with
previous year’s comments can be made. This should provide a further insight into the trends in beach
response.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
Overview
In general, there has been limited change to the beach profiles over the year, however there continues
to be a trend of erosion at:
 Aberaeron South Beach (Both profiles);
 Aberarth (at HAT and MHWS);
 Llansantffraed (Both profiles).
The response of the beaches at Aberystwyth has been varied. Many profiles are quite stable, however,
the southern section of South Marine Terrace continues to erode along with the southern section of
Marine Terrace, increasing the susceptibility of these areas to storm damage.
The trend of erosion of the seaward face of the Pen-yr-Ergyd spit continues, while accretion continues
around the head.
On Tan-y-Bwlch there has been more movement on the northern part of the beach than the southern.
In the future Profiles 3 to 7 may be of concern as these show a slight continuing trend of erosion at
the 6m level.
Monitoring Summary & Areas of Concern
As part of a coastal monitoring programme, Ceredigion County Council annually undertake
topographic surveys and profile surveys along various sections of the Ceredigion coastline. This is
the seventh year that the 42-profile survey has been undertaken at 12 locations along the coast. This
report provides a summary of the major changes that have occurred during the period of monitoring,
with particular attention paid to those changes occurring over the period between August 2000 and
2001
Each area is discussed individually describing the changes, concerns and what actions are required. In
general, only limited changes have occurred to the profiles this year with the erosional trends
previously seen on a number of profiles being abated or even reversed.
Eight areas of concern are listed below, although some are more severe than others: 
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Pen-yr-Ergyd – The continued erosion of material at the root of the spit may eventually lead to
a breach if left unabated;
Aberporth – The lowering of the berm in front of the channel could lead to an increase in the
exposure of the sea defences behind the beach;
South Beach Aberaeron – The continuing loss of material below MHWS;
Llansantffraed – The continued erosion at all levels of the beach;
Tan-y-Bwlch – The slight erosion on Profile 6 at crest level;
South Marine Terrace – The removal of the material to the southern end of the beach which
increases the susceptibility of the structure to future storm damage;
Victoria and Marine Terrace – Continued erosion to the southern end of Marine Terrace and
the further exposure of the sheet piling toe protection;
Borth – The continued erosion of the shingle bank especially on the southern end, which
provides the main defence for Borth Village.
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Cardigan Bay Coastal Group
6th Annual Overview 2001 / 2002
The following actions have been recommended this year:
1. The condition of the beach over the southern area of South Marine Terrace continues to be of
concern and over the winter months should be visually monitored following storms to identify
any sudden removal of beach material, which may undermine the structure.
2. The repair of the groynes on Aberaeron South Beach is recommended to abate the erosional
trend over the beach.
Pembrokeshire County Council
The North Coast of Pembrokeshire largely consists of pocket bays within hard rock cliffs. Where
development has occurred in the bay hinterland, defences, in the form of random rubble walls have
been constructed. Monitoring has been undertaken as a regular planned activity on a 3-year
programme of inspection with the data being entered into the County Council database.
The shingle bank at Newgale is vulnerable to breach by severe storms necessitating the closure of the
A487 and the possible evacuation of several properties. An analysis has been undertaken by Posford
Haskoning, which defines the offshore wave and tide parameters that could threaten the stability of
the bank. This information will form the basis of the Environment Agency Flood Warning alarm for
the area.
The SMP has defined new monitoring requirements, which will be considered by both the Council
and the Group in the course of the next year.
Environment Agency
Monitoring report for the SW Area of Environment Agency (i.e. as far North as Wallog):
a) Coastal Defences identified in Agency's "Sea Defence Survey" have undergone a repeat condition
assessment. No significant changes since original inspections of winters 98/99 and 99/00.
Afon Teifi and floodplains have been subject to aerial survey using "LIDAR". Results expected
imminently. Includes estuary to approx 100m downstream of Pen yr Ergyd spit. Will provide spot
height data to approx 2m grid resolution and will be invaluable in determining full extent of flood risk
areas.
b) The Environment Agency is developing a database called "NFCDD" as part of High Level Targets.
It will include Fluvial Flood Defences, Sea Defences and Coast Protection Structures.
c) Agency's website is www.environment-agency.gov.uk (Includes information about "NFCDD").
On a national level, EA have been undertaking several 'Asset Management' Projects over last few
years, including an update / revision to the ex-NRA's "Sea Defence Survey" of 1990. This has
involved the referencing and assessment of coastal structures under the same system as used for the
assessment of fluvial structures (known as FDMS).
The new 'Sea Defence Survey' has included both formal Sea Defences (e.g. Fairbourne) and those
Coast Protection structures, which are considered to offer significant flood protection (e.g. Borth).
The data from this update will be input to NFCDD. (NB NFCDD will succeed FDMS).
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6th Annual Overview 2001 / 2002
Cardigan Bay Coastal Group
Railtrack
No coastal monitoring has been carried out in the year to March 2002 although normal cyclic
examinations of bridges and structures continues and includes: 
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Friog Cliffs lower sea wall No 0 monitored every 3 months
Llwyngwril Clay Cliff erosion monitored every 3 months
Information in both general and specific terms regarding Railtrack’s business, tasks, network and
environmental & corporate responsibilities is held on their web site http://www.railtrack.co.uk
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