Brian Baily

Techniques for monitoring coastal change: a review and case study

The coastal zone is increasingly being used for a diverse array of often conflicting uses. Recent approaches to coastal management have highlighted the need to base management practices on a detailed understanding of the processes at work within the coastal zone. This article discusses some of the methods available which coastal managers can use to examine the historical evolution and behaviour of areas of the coastline. It is suggested that an understanding of such changes can help the understanding of the effects of past management practices and help to plan future strategies. The use of cartographic and photogrammetric analysis is exemplified through a case study of East Head Spit, West Sussex, UK.

Change Detection Mapping and Analysis of Salt Marsh Areas of Central Southern England from Hurst Castle Spit to Pagham Harbour

Abstract This paper describes a research project that has been conducted as part of the coastal habitat and management plans initiative (ChaMPs). The primary aim at this stage is to identify and quantify the salt marsh decline by mapping the changing extent of salt marsh coverage during the last 30 years. Rectified aerial images of the salt marsh were created for three epochs. The salt marsh and coastal boundaries were then mapped using a head-up digitising technique combined with stereo aerial photo interpretation. This methodology, though simple, provides an important estimate of salt marsh change for a number of harbours and estuaries in southern England. The results show a rapid decline in salt marsh habitat, with some areas showing a reduction of over half their existing salt marsh between 1971 to 2001. The authors consider the various theories that have been presented to account for this dramatic change and offer preliminary explanations. Though no doubt resulting from the combined effects of rising sea levels, Spartina dieback, restricted sediment supplies, pollution, and coastal squeeze, the authors underline the need for more detailed case studies of specific sites in the future.

Identification and quantification of weathering by plant roots

Small weathering forms were produced on polished marble tablets by the etching action of plant roots. Imagery of the forms was obtained with a high quality photogrammetric scanner. Automated classification methods, used in image processing, proved inadequate for identifying etched areas, but observer defined mapping within a GIS was able to identify and map the extent and intensity of etching across a range of scales. Root etching patterns were not apparently influenced by forms produced during tablet preparation. Root etching occurs across grains and at grain boundaries, and appears to be more intense at the junction of root networks.

EVALUATION OF LONGSHORE SEDIMENT TRANSPORT MODELS ON COARSE GRAINED BEACHES USING FIELD DATA: A PRELIMINARY INVESTIGATION

Detailed studies have been undertaken to assist in the design of major extensions to the port of Haifa. Both numerical and physical model studies were done to optimise the mooring conditions vis a vis the harbour approach and entrance layout. The adopted layout deviates from the normal straight approach to the harbour entrance. This layout, together with suitable aids to navigation, was found to be nautically acceptable, and generally better with regard to mooring conditions, on the basis of extensive nautical design studies.Hwa-Lian Harbour is located at the north-eastern coast of Taiwan, where is relatively exposed to the threat of typhoon waves from the Pacific Ocean. In the summer season, harbour resonance caused by typhoon waves which generated at the eastern ocean of the Philippine. In order to obtain a better understanding of the existing problem and find out a feasible solution to improve harbour instability. Typhoon waves measurement, wave characteristics analysis, down-time evaluation for harbour operation, hydraulic model tests are carried out in this program. Under the action of typhoon waves, the wave spectra show that inside the harbors short period energy component has been damped by breakwater, but the long period energy increased by resonance hundred times. The hydraulic model test can reproduce the prototype phenomena successfully. The result of model tests indicate that by constructing a jetty at the harbour entrance or building a short groin at the corner of terminal #25, the long period wave height amplification agitated by typhoon waves can be eliminated about 50%. The width of harbour basin 800m is about one half of wave length in the basin for period 140sec which occurs the maximum wave amplification.Two-stage methodology of shoreline prediction for long coastal segments is presented in the study. About 30-km stretch of seaward coast of the Hel Peninsula was selected for the analysis. In 1st stage the shoreline evolution was assessed ignoring local effects of man-made structures. Those calculations allowed the identification of potentially eroding spots and the explanation of causes of erosion. In 2nd stage a 2-km eroding sub-segment of the Peninsula in the vicinity of existing harbour was thoroughly examined including local man-induced effects. The computations properly reproduced the shoreline evolution along this sub-segment over a long period between 1934 and 1997.In connection with the dredging and reclamation works at the Oresund Link Project between Denmark and Sweden carried out by the Contractor, Oresund Marine Joint Venture (OMJV), an intensive spill monitoring campaign has been performed in order to fulfil the environmental requirements set by the Danish and Swedish Authorities. Spill in this context is defined as the overall amount of suspended sediment originating from dredging and reclamation activities leaving the working zone. The maximum spill limit is set to 5% of the dredged material, which has to be monitored, analysed and calculated within 25% accuracy. Velocity data are measured by means of a broad band ADCP and turbidity data by four OBS probes (output in FTU). The FTUs are converted into sediment content in mg/1 by water samples. The analyses carried out, results in high acceptance levels for the conversion to be implemented as a linear relation which can be forced through the origin. Furthermore analyses verifies that the applied setup with a 4-point turbidity profile is a reasonable approximation to the true turbidity profile. Finally the maximum turbidity is on average located at a distance 30-40% from the seabed.

Assessing historical saltmarsh change; an investigation into the reliability of historical saltmarsh mapping using contemporaneous aerial photography and cartographic data

Habitat protection, creation and management are at the forefront of nature conservation throughout the world. Many terrestrial and marine ecosystems are under pressure from a diverse range of issues including impacts associated with climate change, multiple resource use and increased development. Saltmarsh within the United Kingdom, is one such valuable habitat which has suffered significant losses over the last eighty or so years. Any environmental management practice or decision applied to these areas, should ideally be based on evidence of processes and change. One potential way of measuring saltmarsh change is by using historical maps and aerial photographs to look for patterns of growth or reduction. This research examines the process of saltmarsh mapping and compares historical aerial photographs and maps to assess their suitability for habitat change assessment. This research suggests that whilst historical aerial photography can be accessed and utilised effectively, the data presented on maps should be treated with a great deal of caution. The saltmarsh represented on the maps used in this research was noticeably different from that mapped using aerial photographs from a similar time period. Whilst this does not dismiss the use of historic maps along this part of the coast, it does suggest they should be treated with some degree of caution and will vary in their reliability.

Mapping the intertidal vegetation of the harbours of southern England for water quality management

This paper discusses a research project dealing with the mapping of the intertidal vegetation of several harbours along the southern coastline of England. It describes in detail the methods used to map the vegetation and gives examples of the results from these studies. This paper then goes on to explain how these results are applied by the Environment Agency of England and Wales to improve water quality in the harbours. This type of vegetation mapping is useful in monitoring the development of the intertidal species includingSpartina, Zostera and of particular importance to this study the green algaeUlva andEnteromorpha. The work was undertaken with funding from the Environment Agency and at present has taken place over a four year period. The data collected will be used by the Environment Agency to assess macro-algae covervalues for the intertidal area of the harbours concerned. This forms part of the Agencys commitment to the EU Nitrates Directive and the Urban Waste Water Treatment Directive. Some of the species mapped act as suitable indicators of water quality and are symptoms of entrophication. Other species are of interest for nature conservation and were recorded to provide a record for longer-term trends in vegetation patterns within the harbour. This paper aims to provide readers with an understanding of the techniques involved as well as an evaluation of the methodology.

The Development of a Simplified Model for Urban Flood Risk Mitigation in Developing Countries

The prevalence of flooding in the world in recent times has arguably been unprecedented. It is particularly challenging for developing countries such as Nigeria, where the hazard is often poorly understood and understudied. With predictions of worse future scenarios, it is important to develop integrated approaches - which include flood modelling and vulnerability assessment - aimed at assisting human populations to cope with the hazard. This paper presents an ongoing research into flood risk mitigation in the Lagos metropolis of Nigeria. Maps of social vulnerability index, and land cover of the area have been produced. The results tend to show that two-thirds of the study area may be classed as highly vulnerable to the hazard, with Ajeromi-Ifeledun local government area, most vulnerable. Rapid urbanization tends to expose a wider population to flood risk as new developments are increasingly being put up in flood-prone areas. While this research is at a relatively early stage, the interim results will inform flood risk mitigation efforts in the study area.

The Development of the Photogrammetric Mapping of Tidal Lines by the Ordnance Survey

Abstract title/> Coastal maps and charts represent one of the few longer-term datasets which can potentially be used to analyse coastal change over the last 200 years. Mapping of coastal areas has often been unreliable, inconsistent and a low priority. One feature which has been mapped periodically is the line of the high and low water lines of the tides. Tidal line mapping has periodically been carried out by the Ordnance Survey throughout the late nineteenth and first half of the twentieth centuries; data were largely recorded using land survey techniques. The Ordnance Survey was legally obliged to map and print the tidal lines of coastal areas as they represented the seaward edge of the parish boundary. Tidal lines are transient features and were often difficult, if not dangerous to record in the field. As a result, from 1947 onwards, the Ordnance Survey experimented with photogrammetric techniques in an attempt to improve the consistency and reduce the costs of tidal surveys. This paper reviews the mapping of tidal lines and in particular discusses the evolution and development of photogrammetric mapping techniques by the Ordnance Survey as applied to tidal line surveying.

Tidal Line Surveying and Ordnance Survey Mapping For Coastal Geomorphological Research

Abstract Understanding and predicting coastal change and associated sea level rise are crucial issues in coastal planning and management. Any data which increase the understanding of the long term behaviour of the natural environment are particularly important. Tidal lines, as indicated on Ordnance Survey maps, have been used and have the potential for the geomorphological analysis of changes in beach width and possibly as indicators of sea level rise and beach erosion. Tidal lines represent clearly resurveyed, temporally and spatially transient features which predate aerial photography as a potential source of evidence of coastal change. However, any use of these features requires an understanding of the reliability, repeatability and practicality of trying to map an ambiguous feature in the field. This research principally deals with tidal line definition, data capture and the practice of the ground survey mapping of tidal lines on the Ordnance Survey maps of England and Wales from 1868 until the 1960s.