Regional Coastal Monitoring Programmes
The frontage of the English coastline totals approximately 5,672 km (based on SMP2 mapping). Since 2011, coastal monitoring has been conducted by an integrated network of six regional coastal monitoring programmes, on behalf of the Coastal Groups of England. The boundaries of the six regions are based around coastal sediment cells (Motyka and Brampton 1993), thus inherently working with natural coastal processes. The data collection regime for the six regional programmes was designed using a generic risk-based approach, but tailored to local requirements.
Prior to the establishment of the National Network of Regional Coastal Monitoring Programmes in 2011, coastal monitoring centred on local problems, beach management schemes, academic studies or, occasionally, a vision for a more strategic approach to beach management e.g. the Anglian region programme, which dates back to 1990. In some instances, monitoring programmes were developed in response to conditions of planning consents for major coastal schemes e.g. Scarborough BC, Arun DC. A number of excellent local monitoring programmes were developed over time, some of which contained data sets which extended over a period of more than 20 years e.g. New Forest DC, whilst the earliest continuous monitoring programmes include those dating back to 1974 (Bournemouth BC) and even back to 1951 in the case of East Riding of Yorkshire's continuous monitoring of cliff recession (Lee, 2011). Many monitoring programmes were linked specifically with beach management, coast protection and flood defence schemes; in some instances scheme-specific monitoring was the only form of regular monitoring undertaken.
However, despite the good practices of some authorities, the approach to coastal monitoring was both ad-hoc and unsatisfactory in terms of shoreline management; there was considerable inconsistency in the type of data collected or the data collection methodology, or in provision of metadata to support the data quality and origins.
The catalyst for the development and implementation of coastal monitoring programmes at a regional scale undoubtedly was the Shoreline Management Plan since this is the key strategic level at which coastal decision-making takes place. The experience and practice of local monitoring schemes thus extended into the development of the first regional coastal monitoring programme in the Southeast (2002 to 2007 and 2007 - 2012), followed shortly by a similar programme in the Southwest (2006 - 2011).
Subsequently, it was realised that the content of the regional programmes was suitably similar that key national targets could be achieved with closer integration of the other regional programmes under a banner of a national network of regional coastal monitoring programmes. Accordingly, the best elements of each of the regional programmes were drawn together into monitoring guidance to encourage consistent good practice. The first 5-year phase of the national network of regional coastal monitoring programmes (referred to hereafter as the Programme) was implemented on 01 April 2011.
Each of the six regional programmes collects the coastal monitoring data needed to underpin sound coastal management and engineering decisions, tailored to the particular characteristics of the region.
The Northeast region (Cell 1, Berwick-upon-Tweed to Flamborough Head) is characterised by large areas of unmanaged shoreline fronting zones of low population density; these are separated by a series of large population centres where defences and risks are concentrated. The coastal landforms vary considerably, comprising low-lying tidal flats with fringing salt marshes, hard rock cliffs that are mantled with glacial till to varying thicknesses, softer rock cliffs, and extensive landslide complexes. Although the majority of the 375 km of shoreline is very exposed to severe wave action from the North Sea, much of the geology is very resistant and changes are consequently small at many locations. Dynamic management solutions such as beach recharge are infrequent and the need for spatially and temporally dense data is generally low as a result. Dune features are evident along much of the coastline and the habitats and evolution at these sites are both significant in management terms; these sites merited more detailed monitoring than was done previously.
The East Riding of Yorkshire region (Cell 2a, Flamborough Head to The Humber), although the smallest of the regions in terms of coastline length at 127 km, is characterised by rapidly-eroding soft cliffs and has some of the highest coastal erosion rates in the UK.
The Anglian region (Cells 2b and 3, The Humber to Canvey Island) comprises typically soft cliffs along the Norfolk, Suffolk and Essex coasts. Changes in management policy require more detailed monitoring to inform adaptation measures in some areas, where population centres are small but erosion rates high e.g. Cley-Salthouse and Happisburgh. Wave climate is quite variable due to the varied orientation of the 987 km length of coastline. The over-riding risk is clearly linked to coastal flooding, which impacts heavily on much of the region and large swathes of land and population centres are vulnerable (as highlighted by the North Sea surge events in 2007 and 2013). The Wash, and significant areas of North Norfolk, Suffolk and Essex are heavily designated under international, European, national and local level nature conservation designations. Dynamic beach management solutions are common, requiring good quality management data e.g. Lincshore; most are usually limited to capital recharge, but smaller less frequent recycling projects are included. Population centres are spread, with larger centres typically based around ports e.g. Grimsby, Lowestoft, and many areas of coast front farmland or areas of low population. National critical infrastructure, such as nuclear power stations e.g. Sizewell also require good survey data.
The low-lying land in the Southeast region (Cells 4 and 5, Isle of Grain to Portland Bill) is vulnerable to flooding and the soft sedimentary geology across the region is frequently vulnerable to erosion. Most of the 1,236 km of coast is vulnerable to either erosion or flooding. Exposure is quite variable, with a series of large harbour systems and some considerable areas of wetlands. Approximately 10% of the population are at risk from flooding and billions of pounds of infrastructure are at risk.
The Southwest region (Cells 6, 7 and 8, Portland Bill to Chepstow including the tidal limits of the Severn estuary beyond Gloucester) is the largest region, encompassing 2,019 km of coastline. The region is characterised by extensive areas of unmanaged coastline and low rates of erosion arising from the resistant geology. Population centres are generally widespread. The coastline is punctuated by a series of estuarine systems which are of nature conservation significance. The risks to property arising from erosion are generally small but sections of the Somerset coast are extremely low lying and are subject to coastal flood risk. The Southwest is the most exposed of all the regions in terms of wave climate, and incurred extensive storm damage during the winter 2013/14. The estimated cost to the economy in the Southwest as a result of the seawall damage at Dawlish is ₤1.2 billion.
The Northwest (Cell 11, Great Orme to Solway Firth) is generally more sheltered than most other parts of the country with protection from south-westerly storms afforded by Ireland, but with extensive sections of the 928 km of coastline vulnerable to large waves from the northwest which can propagate through the North Channel. Large scale erosion is evident in some areas, in particular the coastal dunes. Extensive estuarine evolution is prominent with massive changes occurring in the Morecambe Bay area. Population centres are spread along the frontage and a number of high population density holiday towns lie within at risk zones e.g. Blackpool.
The primary objectives of the monitoring programme are:
- To assist coastal managers by providing them with relevant information on which to make sustainable future shoreline management decisions
- To assist in the definition of the magnitude of risks of coastal flooding and erosion and to provide data to support re-evaluation of those risks in the future.
- To improve understanding of coastal process behaviour and how those processes interact with the shoreline.
Programme design method
A generic monitoring schedule for every SMP2 Policy Unit along the coastline was designed according to the local coastal risks:
- Exposure to wave attack
- Coastal flood risk
- Geomorphology/defence type
- Management policy
- Hold the line (HTL)
- Managed re-alignment (MR)
- No active intervention (NAI)
- Advance the line
- sites with a formally agreed management plan, usually associated with capital projects such as beach recharge schemes, or
- sites with informal beach management plans, associated with any form of beach intervention, such as beach recharge, bypassing, scraping or recycling
- Assets at risk
- Properties and other assets within the 1:200 year return period coastal flood zone
- Properties and other assets within the 100 year erosion risk zone
- Coastal habitats as defined in Biodiversity Action Plans
Exposure to wave attack
Three broad subdivisions were determined for the exposure analysis category based significant wave height (Hs) and sediment transport rate. These were originally derived from Futurecoast, SMPs etc., and reviewed using data from the coastal monitoring programmes.
|Risk criteria for exposure to wave attack||Example|
|High||Open coast, design Hs typically > 1.5 m or sediment transport rate > 10,000m3/year||Porthleven|
|Medium||Design nearshore Hs < 1.5 m or sediment transport rate < 10,000 m3/year||The Solent|
|Low||Design Hs < 1 m||Exe estuary|
Coastal flood risk
The polygon delimiting the Environment Agency 1:200 year flood risk zone was used to identify the coastal flood risk zone, and was expanded to take into account potential sea level rise.
A series of generic categories are determined for each stretch of shoreline, based on Futurecoast and SMP2's and from the current phase of coastal monitoring programmes. The highest risk systems are generally considered to be the most dynamic combinations of geomorphology and defences. For example, barrier beaches, inlet entrances, nearshore bars and ebb deltas are all considered to be volatile systems that may evolve both rapidly and at large scale. Natural systems such as dunes and saltmarshes tend to evolve at slower rates generally, but may have major impacts of the defence standards e.g. reduction of overtopping rates. Geological controls are evident at many sites which control the rate of change, even under the most exposed conditions. For example, the hard rock geology of the southwest peninsula evolves at a very slow rate.
|Coastal geomorphology and coastal structures||Risk category|
|Barrier beach/shingle ridge with groynes||High|
|Open beach backed by cliffs||High/Medium|
|Open beach backed by seawall||High/Medium|
|Cliffs with beach and groynes||High/Medium|
|Seawall with groyned beach||High/Medium|
|Cliffs with shore platform||Medium|
|Seawall with shore platform||Medium|
|Seawall with rock revetment||Medium|
|Rock revetment with shore platform||Medium|
|Rock revetment with beach||Medium|
|Rock revetment with beach and groynes||Medium|
|Other hard defence/structures||Medium|
|Hard rock cliffs with no beach||Low|
|Cliffs with hard rock platform||Low|
Four basic shoreline management policies were used to define coastal sites:
Most of the categories are self-explanatory in context with conventional SMP terminology. A further operational category defined as "beach management plan" sites (BMP) describes:
Both HTL and MR policies also require adequate investment in monitoring of asset performance and these are considered in the medium risk category. No active intervention is considered to be in the low risk category, in monitoring requirements terms, although this is qualified where there have been recent policy changes and data is required to understand the implications of the new policy or where the behavioural unit is directly linked (in terms of sediment transport) to a BMP or HTL site.
Assets at risk
The following assets at risk were identified:
In England, 2,750 km of shoreline is at risk from flooding, whilst 2,500 km may be subject to erosion. Approximately 105,000 properties lie within the at-risk tidal flood zone. A total of about 3,800 km2 of coastal BAP habitats was identified.
The local differences in coastline and the risks being managed mean that programme composition varies regionally, but typically includes some combination of:
- Beach profiles/topographic data
- Costs and repetition are reduced
- Data management is co-ordinated and integrated within a single framework
- Linkages and awareness are made between strategic and operational parts of organisations
- Aerial photography surveys
- Soft, rapidly eroding cliffs
- Estuarine wetland areas
- Dune systems
- Where access to the beach is difficult
- Hydrodynamics (waves, tides)
- Terrestrial ecological mapping
- Other monitoring
- Satellite imagery is used for monitoring the evolution of the large scale changes in Morecambe Bay. This technique is particularly suitable to monitor the large and highly mobile sand banks and furthermore is a useful test case for the development of the technology and improvements in resolution, and its potential applicability in other areas in the future
- ARGUS cameras are used to monitor impacts of seawall scour at Cleveleys. The analysis techniques being developed by this system have potentially useful engineering applications since they can remotely provide near real-time information on beach levels
- Bathymetric lidar is being trialled in the Southwest (where the sea conditions make it most likely to be successful). At present, it is thought to be less suitable for the more turbid waters of much of the rest of the English coast, but the trial will provide the opportunity to assess its capabilities for inter-tidal and sub-tidal hydrographic surveys or for emergency post-storm surveys
- Laser scanners are increasingly being adopted for baseline topographic surveys, with the addition benefit of capturing high density beach data including backing cliffs and structures
Beach profile/topographic data
All programmes include topographic surveys, although the frequency and method of survey varies. In most cases the data serves both operational requirements e.g. scheme development and operational maintenance, and strategic requirements. Such combined programmes offer the following advantages:
The risk framework indicates the frequency and spatial distribution of survey, which is subsequently fine-tuned for each location based on local knowledge and experience.
|Frontage category||Land-based topographic surveys||Detailed spot height (baseline) survey||Post-storm survey (1:1 year threshold event)|
|High risk BMP sites||Bi-annual||Annual||Call-off|
|HTL or MR, high exposure||Bi-annual||5 years||Call-off|
|HTL, low- exposure||Annual||5 years||Call-off|
|NAI accessible beach||Annual||5 years||Call-off|
|NAI inaccessible hard cliff site||Lidar (5 years)||None||None|
In most regions, the main focus of the bathymetry survey programme has shifted towards swath (multibeam) bathymetry i.e. 100% seafloor coverage, with some single beam bathymetry over shallow banks, ebb tide deltas etc.
The whole coastline is flown to Mean Low Water Springs at least once in the 5-year phase. Frequent aerial surveys are advantageous for assessment of the rapidly eroding cliff frontage within the Cell 2a (East Riding) programme (which in combination with lidar replaces topographic surveys). In most regions, near-infrared imagery is captured at the same time as the aerial photography, which has proved useful for subsequent terrestrial ecological mapping.
Lidar is widely used by all regional programmes, typically with a resolution of 1m, but at 0.5m resolution in selected areas such as Chesil beach. Each region receives a flight of its entire coastline to Mean Low Water Springs once in the 5 years, supplemented by targeted areas e.g. sand dunes, soft cliffs etc. in intermediate years. Along the rapidly-eroding frontage of Cell 2a (East Riding), twice-yearly lidar and aerials replace topographic profiles. Lidar is particularly effective to capture:
Lidar is generally not used where timing of surveys is important such as post-storm surveys, or where repeated coverage of the low inter-tidal zone is required.
Hydrodynamics (waves, tides)
All regions collect measurements at heavily-managed beach management sites, at high risk locations or where schemes are under development at sites where numerical wave predictions are difficult. An additional benefit is the real-time delivery of the wave data, delivered principally through the Channel Coastal Observatory or for Anglian Region via WaveNet. The real-time data is also transferred to the Environment Agency's Flood Forecasting Service and to the Met Office. Originally, the real-time data was merely a useful check on the operational status of the buoys but, over time, the real-time data has become increasingly important for beach operations and flood warnings; usage of the real-time data is extremely high, from a wide range of users.
All regions include regular reporting of wave climate statistics and storm analysis to update design and management conditions.
Tidal monitoring does not form a major part of the regional programmes as there is, rightly, a reliance on data from the A-class gauges operated by the National Sea Level and Tidal Facility. Nevertheless, there are some local requirements for additional site-specific measurements. The tide gauges installed by the coastal monitoring programmes were sited after considerable discussion with NTSLF and the Permanent Service for Mean Sea Level (PSMSL) to nest inside the A-class gauge network, to provide real-time tide data where surge forecasting is less reliable (usually due to local factors) or where no representative tide data is available e.g. the gauge deployed by the Southwest region at Port Isaac, Cornwall, which provides the only real-time coastal tidal data between Land's End and Ilfracombe. The instruments and maintenance schedule are GLOSS-standard. In addition to being made freely available via the Programmes' website, the real-time data (1 second) data are also forwarded instantly to the International Oceanographic Commission's Sea Level Monitoring Facility where they are used, amongst other things, as part of the tsunami warning service for the UK http://www.ioc-sealevelmonitoring.org/index.php
Terrestrial ecological mapping
Terrestrial ecological mapping from the aerial photography is undertaken once per 5 year phase. The habitats mapped vary within the regions but cover principally the dynamic priority BAP habitats.
A range of alternative monitoring approaches are adopted within some programmes, to examine local problems within the broader regional context. For example:
Some other local measurements are made according to specific needs, such as met stations, Compact Airborne Spectrographic Imager (CASI) surveys, geophysical surveys, clay level monitoring, piezometers and cliff monitoring and sediment sampling.
Lee, M. A. (2011). Reflections on the decadal-scale response of coastal cliffs to sea-level rise; Quarterly Journal of Engineering Geology and Hydrogeology, 44, 481-489
Motyka, J. M. and Brampton, A. H. (1993). Coastal management: mapping of littoral cells; HR Wallingford Report SR328