Developing Techniques to Visualise Future Coastal Landscapes

Developing Techniques to Visualise Future Coastal Landscapes Simon JUDE, Andrew JONES, Ian BATEMAN and Julian ANDREWS

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Introduction

With sea levels predicted to rise by up to 88cm by the year 2100 (CHURCH et al., 2001), coastal managers are beginning to consider the use of ‘soft’ approaches to defend the coast. Unlike traditional ‘hard’ forms of defence, these use natural processes and landforms to protect the coast. Unfortunately though, not only do such interventions have the potential to cause conflict, but also to have large impacts on coastal landscapes. Therefore if these new approaches are to be accepted by members of the public then coastal managers must involve them in participatory decision-making processes. By doing so, the potential for conflict and opposition to plans may be reduced. However, coastal managers are often criticised for failing to involve the public in decision-making processes, and of only informing them of decisions once they have been made. In relation to this the United Kingdom Government have recognised that significant difficulties are associated with facilitating public participation in management decisions, and have called for the development of innovative communication techniques to improve the situation (MAFF, 2000). Likewise, similar calls have also been made by the European Union through their Demonstration Programme on Integrated Coastal Zone Management (ICZM) (BELFIORE, 2000; KING, 1999). A number of possible solutions that may assist in widening public involvement in coastal decision-making and in the dissemination of management information have been suggested. These have included the use of traditional forms of media such as information leaflets, maps and video, accompanied by public meetings, exhibitions and consultation exercises to gain feedback regarding proposed coastal management schemes. However, of most interest have been calls by those such as KING (1999) to develop new electronic means of communication to assist in the deliberative process. In terms of developing new communication methods for use by coastal managers we believe that visualisation techniques provide an opportunity to aid and develop public involvement in coastal zone management. To illustrate this, this article presents some of the findings from ongoing research that shows that it is now possible to produce realistic visualisations of different coastal management policies. Furthermore some of the difficulties associated with visualising coastal environments that have been encountered will be described together with some suggestions for future research to overcome them.

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S. Jude, A. Jones, I. Bateman and J. Andrews

The North Norfolk Coast

To develop the visualisation methodology two small project-level study sites located along the north Norfolk coast at Brancaster and Holme-Next-the-Sea (Holme) on the east of England have been used. This is a low-lying barrier coastline of high scientific, economic and recreational value that is subject to a wide range of conflicting interests that exist between those wishing to protect the coastline and those wanting economic development. Furthermore, in recent years such conflicts have been exacerbated by the increasing concerns about the potential impacts of future sea level rise on the coastline. This is because it is highly vulnerable to North Sea storm surges (THUMERER et al., 2000) that caused widespread flooding in 1953, 1973, and more recently in 1993 and 1996. As a result of these concerns new defence methods such as managed realignment are being discussed for protecting this section of coast including the reversion of internationally important freshwater habitats and nature reserves to saltmarsh (Clayton, 1993; Andrews et al., 2000). In terms of the study sites at Brancaster a managed realignment scheme has recently been completed, whilst at Holme a number of realignment options are under consideration.

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GIS Database Construction and the Assessment of Future Coastal Change

The first stage of the research involved the development of an extensive GIS database. This contained data from a range of organisations involved in managing the coast, and was supplemented by commercial products from the UK national mapping agency, the Ordnance Survey. These included the Ordnance Survey’s Land-Line.Plus 1:2,500 largescale vector data and Land-Form PROFILE 10m resolution DEM products. Fortunately one of the advantages with studying such a scientifically important and vulnerable section of coastline was that extensive data was available from a range of sources due to the comprehensive monitoring programmes managed by the Environment Agency and also from academic research projects. Once the GIS database had been created a methodology for assessing how the sites would change in the future was developed. Not only did this account for management interventions, but also future sea level rise and historical coastline change. This employed historical coastline change data including historical maps, aerial photography, and coastal monitoring data from which past patterns of shoreline change could be identified. This was complemented by future management intervention information provided by the Environment Agency, whilst predicted sea level rise was calculated using the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC), (HULME et al., 1995) together with isostatic change values for land levels in Eastern England (SHENNAN, 1989). The Ordnance Survey’s Land-Line.Plus large-scale digital line data was used for the detailed visualisation work and required conversion to a polygon topology to allow landcover attribute data to be incorporated. One of the difficulties encountered with this data was that the dynamic nature of the coastline resulted in many of the shoreline features

Developing Techniques to Visualise Future Coastal Landscapes

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at the study sites either being missing or in different locations in the Land-Line.Plus data when compared to recent aerial photography for the sites. To overcome this updating of the Land-Line.Plus data was required based on the aerial photography, a process that was extremely time-consuming. To further complicate this, whilst commercial aerial imagery was available from which the data could have been updated it had been collected at unknown tidal states. For example, at Holme imagery from alternative flight runs at different tidal states had been mosaiced. As a result the imagery was unsuitable for the updating of those geomporphological features in the intertidal zone that had changed since the Ordnance Survey had last surveyed the site. To overcome this, specially commissioned aerial photography collected by the Natural Environment Research Council’s Airborne Remote Sensing Facility at low tide for the study sites was used to update the LandLine.Plus data. Once the land-Line.Plus data had been updated, landcover attribute data was manually assigned to each of the polygons using a combination of three separate landcover data sources. These included colour aerial photography, 5 metre resolution Compact Airborne Spectrographic Imagery (CASI) classified for the intertidal zone and the Centre for Ecology and Hydrology (CEH) Landcover Map of Great Britain. This produced comprehensive land cover polygon dataset representing the sites. The landcover coverages representing the sites following the management interventions were produced using two alternative approaches. For Brancaster, plans were obtained from the Environment Agency and digitised and appended to the Land-Line.Plus coverage illustrating how the site may look once the scheme has matured (TYRRELL and DIXON, 2000). This information was combined with the results of sea level rise assessments and information on historical coastline change to illustrate how the site would change because of the scheme. For the Holme site because detailed management plan data was unavailable, details of possible management interventions were used as the basis of the visualisations. This was combined with the sea level rise and historical coastline change information to produce visualisations for a number of alternative management scenarios, including a partial realignment of the site which is presented here. Changes in terrain at the sites resulting from the proposed management interventions were represented by reprofiling the DEMs where details of terrain changes were available from the Environment Agency.

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Visualisation Production

Visualisations for the study sites were produced using two techniques. Firstly interactive visualisations were produced using ArcScene in ArcGIS, providing 'fly-through' Virtual Reality Modelling Language (VRML) experiences. Secondly, static visualisations were produced by exporting the GIS results into World Construction Set (WCS), a photorealistic rendering package from 3D Nature. The two methodologies were chosen to allow an assessment of their respective roles in widening public understanding of future coastal management schemes. The production of visualisations using ArcScene involved creating a Triangular Irregular Network (TIN) DEM from the Land-Form PROFILE DEM, over which the landcover

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coverage was draped to create a 3D scene. Sea defences and buildings were added as separate coverages, allowing them to be extruded to produce 3D surface features. For visualisations of the site following the management interventions, the reprofiled DEM was converted to a TIN, and the landcover coverage representing the future site state used as the drape coverage, with the buildings and defences added. ArcScene allows the visualised data to be queried in the same way 2D GIS data can, and provides facilities to enable the user to navigate around the 3D scene in real-time. The 3D scenes were exported as static images and as VRML files for viewing in any Web browser equipped with a suitable plugin. In contrast to ArcScene, WCS allows photorealistic visualisations to be generated, and has the advantage for many GIS users that ASCII DEMs and ArcView shapefile coverages may be imported and used as the basis for these visualisations. The first stage in creating the WCS visualisations involved importing the DEM data to provide the base terrain. One advantage with WCS is that it permits the generation of detailed terrain features and allowed the generation representations of sea defences from defence heights and crosssections as provided by the Environment Agency, and also to create creeks and pools. The second stage involved importing individual ArcView shapefile coverages to which colours, textures and vegetation models were applied. The third stage of the work was the addition of 3D building objects. Due to data constraints generic models representing houses, barns, sheds/outbuildings, glasshouses and churches were used. Although WCS produces static images, a series of images along a camera path can be rendered, allowing the creation of an animation, although the main drawback with this is the long rendering process required to create the images. For example, over 40 hours of rendering was required to create the images used to produce a 33 second animation for the Holme site. However, once the images had been rendered, the creation of AVI files using QuickTime was very simple, the main issue being the need to balance the level of compression to create small AVI files, whilst retaining the detail from the original images.

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The Visualised Landscapes

The visualisations produced using ArcScene and WCS clearly illustrate how the managed realignment schemes would affect the landscapes at the two sites. At Brancaster the visualisations suggest that the realignment scheme will fit in well with the surrounding landscape, although the construction of the set-back defence which comprises of an earth flood embankment has a large visual impact on the site because of its height (Fig. 1 and 2). However if the partial realignment was to go ahead at Holme the visualisations show that it would have a considerable impact on the landscape and recreational amenity of the site. This would be caused by the breaching of the dunes that presently protect the site leading to the creation of extensive areas of muds and pioneer saltmarsh between the dunes and the new set-back defence (Fig. 3). In terms of the visualisations produced, obvious differences between the ArcScene and WCS visualisations are apparent, especially in the level of detail; the former (Fig. 1) being more stylised in comparison to the latter (Fig. 2 and 3). Likewise, the limited functionality in ArcScene resulted in crude representations of 3D features such as defences (Fig. 1),


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produced by extruded shapefiles, whilst WCS rendered them in greater detail (Fig. 2). However, there is a trade off between time and detail, with the low detail ArcScene visualisations able to be produced quickly, whilst the WCS visualisations being much more time-consuming to render. As well as producing static images a number of different types of visualisations were created and these included the VRML files produced by ArcScene that may be viewed by users across the Web by using a browser equipped with a suitable plug-in such as CosmoPlayer. It was however found that the VRML output suffers from two limitations. Firstly, the VRML files created for large sites such as Holme were too large to be viewed on a normal desktop PC once they were created. Secondly, as can be seen from the streaks in the foreground on Fig. 4, the VRML code has difficulties representing certain terrain changes, which has an adverse impact on the quality of the view in the browser. Alternatively the animations produced using World Construction Set can be viewed using any package that can view AVI files. The AVI files were tested using QuickTime and Windows Media Player which allowed the animation to be played, paused or manually controlled using simple controls (Fig. 5).

Fig. 1:

Visualisations of the Brancaster site at present (left) and following the managed realignment scheme (right) created using ArcScene.

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Fig. 2:

A WCS close-up view of the Brancaster West Marshes site before (left) and after the managed realignment scheme (right).

Fig. 3:

WCS visualisations of the Holme site at present (left) and in 2022 following a partial managed realignment (right).


Fig. 4:

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An example of the VRML output created using ArcScene

Fig. 5:

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Viewing the AVI animation created for Holme using WCS and QuickTime in Windows Media Player.

Difficulties Associated with Visualising Coastal Environments

A number of difficulties were encountered with creating the visualisations that are specific to coastal environments. Possibly the greatest problems are caused by the dynamism of the coastal zone, because digital data such as Land-Line.Plus quickly becomes out of date due to the rapidly evolving coastline. As a result, data editing and updating which is timeconsuming, and therefore a costly process for potential users to conduct becomes necessary. Whilst this situation may improve with the introduction of ‘live’ digital databases such as the Ordnance Survey’s MasterMap product, which is continually updated, this may not represent a total solution to the problem because many coastal areas such as the north Norfolk coast are rural in nature and may not be surveyed regularly. The age limitations identified with the Land-Line.Plus were also evident with the LandForm PROFILE DEM provided by the Ordnance Survey. Particularly at Holme the rapid erosion that occurred during the mid 1990s along the site’s foreshore and dunes was not reflected in the terrain data. Unfortunately this is a more challenging problem to rectify without conducting extensive field surveys to create a new DEM and meant that the terrain limitations in the visualisations simply had to be acknowledged. A further drawback encountered with the use of the 10m resolution Land-Form PROFILE DEM was that whilst it provided an excellent terrain surface onto which features can be added, its low vertical and horizontal resolution meant that some coastal features such as small saltmarsh creeks and dunes were not evident in the DEM. One means of overcoming this in the future may be to use high resolution Light Detection and Ranging (LIDAR) DEMs. Unfortunately at present LIDAR DEMs are expensive, not widely available, and their use in creating visualisations is constrained by computer processing limitations. One of the greatest challenges encountered during the production of the visualisations involved the representation of terrain changes at the sites. Even where detailed information regarding how surface elevations would change was available the reprofiling of the terrain was found to be problematic. For example, whilst terrain changes are possible where only simple reprofiling of the DEM is necessary to create an area with a new elevation and a flat profile, the creation of cross-section profiles such as a dune system are more difficult to

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create. In situations where complicated coastal features such as spits like Blakeney Point on the north Norfolk coast (Fig. 6) need to be visualised by coastal managers this could represent a significant challenge. Here not only would the changes in the spit morphology have to be modelled, but techniques allowing the modification of the DEM underlying the visualisations would need to be developed. Unfortunately whilst this could be addressed by linking the visualisation software to coastal evolution models, such models are often unavailable.

Fig. 6:

An example of the complex terrain and landcover found in the coastal zone.

Fig. 7:

An example of the spurious features found when representing tide heights in ArcScene.

The representation of tidal states is particularly important when creating visualisations for low-lying sections of coastline such as the north Norfolk coast that are vulnerable to flooding. However, representing tidal states in the visualisations was found to be problematic because of the poor vertical and horizontal resolution of the DEMs used which produced spurious features when representing tide heights. These spurious features were


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particularly evident when attempting to represent tides in the ArcScene visualisations (Fig. 7). Similarly, tide heights and waves were difficult to represent in the WCS visualisations because models that were suitable for representing offshore waves created very high waves in tidal inlet areas. In these situations separate sea and tidal inlet polygons had to be used to which different wave models were assigned. The coastal zone is an area that comprises of complicated vegetation and sedimentary surfaces (Fig. 6) that were difficult to represent in the visualisations, because whilst coastal features have poorly defined feature boundaries, GIS data is defined using distinct areas. As a result the distinct feature boundaries associated with GIS data caused problems when trying to represent transition zones between features such as those associated with different types of saltmarsh vegetation. Furthermore, this problem was compounded by WCS failing to provide adequate facilities for blending the edges of polygons to represent changes in surface coverage. Unfortunately, whilst this was partly a drawback with the software used it was primarily a limitation with GIS data structures that becomes a more significant issue when working in the coastal zone.

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Potential Coastal Management Applications and Future Research Needs

Whilst visualisation techniques have been investigated for the representation and understanding of coastal processes and geomorphology (e.g. RAPER, 2000), there has been little research investigating their use in participatory coastal zone management. To investigate the potential management applications for the visualisations interviews were conducted with representatives from coastal management organisations. These suggest that the visualisations have a range of potential roles, from using them in management meetings to develop policies for sites, to publishing them in management documents, public meetings and exhibitions, and dissemination on the Web. A number of more advanced applications were also proposed including the visualisation of whole sections of coastline, the representation of long-term temporal changes, and the visualisation of historical coastlines to aid in the presentation of why particular management interventions are necessary. Amongst the functionality that the coastal managers are requesting is the ability to produce real-time updateable and interactive visualisations for use in meetings to develop management options for sites. These would include links to scientific models and the ability for drag and drop editing of the visualisations. However, the ability to achieve this is presently limited by computer processing constraints which lead to long rendering times and prevents the creation of real-time updating visualisations. The interviews also highlighted the potential importance of interactive forms of visualisations that enable users to explore proposed management interventions for themselves. These would allow members of the public to answer any questions that they have about a proposed scheme and to form their own opinions on the possible merits of it. To address this, recent research has begun to investigate the use of real-time software packages such as TerraVista from Terrex to produce more interactive forms of visualisation (Fig.8).


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Fig. 8:

An example of the interactive visualisations for the Brancaster site produced using TerraVista.

Some of the coastal managers interviewed expressed an interest in the possibility of visualising temporal changes in the coastline using animation to aid in the understanding of geomorphological processes and patterns of coastline evolution. Whilst this is possible using WCS to create a series of frames that can be animated it would be an extremely timeconsuming process because a large number of separate landcover and terrain coverages would have to be created for each frames. However, this may be a technique that could be used to represent coastal change over long periods where each frame in the animation illustrates a 10 year change at the site, as this would require the use of fewer landcover and terrain coverages to produce them. Many of the coastal managers who were interviewed are seeking the ability to produce visualisations of both historical and landscapes up to 100 years in the future for use in evaluating the long-term consequences of proposed management options. With the inherent uncertainties associated with predicting even short-term coastal changes this desire to create visualisations over longer timescales highlights the need to develop techniques to represent uncertainty. There are a number of possible ways in which this could be achieved including the creation of Monte Carlo simulation type animations that present the range of uncertainty. Alternatively visualisations representing the best and worse case coastal change predictions or map overlays highlighting zones of uncertainty could be used. This is an important area of future research because the uncertainties associated with proposed management options need to be presented to members of the public if they are to be involved in participatory decision-making processes as it would assist in enabling them to make informed decisions.

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Conclusions

This research highlights the potential role of GIS and visualisation techniques as a tool to assess and visualise future coastal landscapes. It also illustrates how these technologies may be used in the future by coastal managers to present management information to members of the general public. However, a number of challenges face the development of virtual coastal environments if they are to meet the needs of coastal managers.


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Acknowledgements

The authors would like to thank all of the organisations who provided input into the research including the Environment Agency, English Nature, the Norfolk Coast Area of Outstanding Natural Beauty Partnership and the Royal Society for the Protection of Birds. Thanks are also due to the British Geological Survey, Centre for Ecology and Hydrology, Environment Agency, Natural Environment Research Council Airborne Remote Sensing Facility, the Ordnance Survey and Suffolk County Council for providing GIS data. The research was initially funded by an ESRC/NERC interdisciplinary studentship awarded to the lead author whilst ongoing research is funded by the Tyndall Centre for Climate Change Research. All Ordnance Survey data is © Crown Copyright Ordnance Survey. An EDINA/JISC supplied service.

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