A Geographical Analysis of the Intervisibility of the Coastal Areas of Wales for Characterizing Seascapes David R Miller and Jane G Morrice For the Countryside Council for Wales For the Maritime Ireland/Wales INTERREG 1994-1999 The Macaulay Institute Craigiebuckler ABERDEEN AB15 8QH The Macaulay Institute incorporates the Macaulay Land Use Research Institute (MLURI), which is sponsored by the Scottish Executive Rural Affairs Department, and the Macaulay Research Consultancy Services Ltd (MRCS) which is the commercial arm of MLURI. The contracting body for the work described in this report is MRCS. 1 Table of Contents Summary .................................................................................................................................................. 4 1. Introduction .................................................................................................................................. 8 2. Data ............................................................................................................................................ 10 3. Methodology............................................................................................................................... 11 3.1. Radius of view and observer height .................................................................................... 12 3.2. Analyses of Visibility ......................................................................................................... 15 3.2.1. Visibility of the sea from the land .............................................................................. 17 3.2.2. Visibility of land from the sea .................................................................................... 20 3.2.3 Vertical Dimension ..................................................................................................... 23 3.2.4 Classification of coastal views .................................................................................... 24 4. Results ........................................................................................................................................ 27 4.1. Visibility of sea from the land ............................................................................................ 27 4.1.1 Results ........................................................................................................................ 27 4.1.2 Future developments ................................................................................................... 30 4.2. Visibility of land from the sea ............................................................................................ 31 4.2.1 Results ........................................................................................................................ 31 4.2.2 Future development .................................................................................................... 33 4.3 Vertical dimension ........................................................................................................................ 34 4.3.1 Results ........................................................................................................................ 34 4.3.2 Future development .................................................................................................... 38 4.4 Classification of coastal views...................................................................................................... 39 4.4.1 Results ........................................................................................................................ 39 4.4.2 Future development .................................................................................................... 45 5. General Assumptions and Future Improvements ........................................................................ 46 6. General Discussion and Conclusions .......................................................................................... 51 7. Acknowledgements .................................................................................................................... 52 8. References .................................................................................................................................. 53 Appendix 1. Acronyms and Abbreviations ............................................................................................ 55 2 List of Tables Table 1 Examples of distance to the horizon for different heights of object or observer. ......................12 Table 2 Areas of visibility levels with respect to elevation (km2). .........................................................27 Table 3 Areas of visibility levels with respect to aspect (km2). ..............................................................27 Table 4 The range of vertical angle scores for three different distances seaward from the coastline: ....37 List of Figures Figure 1 Digital terrain model of Wales. .................................................................................................13 Figure 2 Theoretical distance to the horizon from selected locations. .....................................................14 Figure 3 Visibility of land, derived using a 10 km radius of view. ..........................................................16 Figure 4 Example of the distribution of regular grid points in the coastal waters, up to a limit of 10 km from the coastline. ...............................................................................................................18 Figure 5 Example of the output of the analysis of the visibility of land from sea, for the area around the Lleyn Peninsula. The land is represented by the model of elevation. ..................................19 Figure 6 (a) Example of the distribution of regular grid points at 1 km x 1 km intervals, up to a 10 km distance landward of the coastline. ............................................................................................21 Figure 6 (b) Example of the output of the analysis of the visibility of land from sea, for the area around the Lleyn Peninsula. The land is represented by the model of elevation... ................................22 Figure 7 Derivation of classification of coastal views: combining visibility calculation and distance from the observer. ......................................................................................................................24 Figure 8 Geographical distribution of the visibility of the sea from the land. .........................................29 Figure 9 Geographical distribution of the visibility of the land from the sea ..........................................32 Figure 10 Intervisibility of the land and sea. (a) Derived from a 1 km grid of target points’ on land, but results produced for both land and sea. (b) Derived from a 1 km grid of ‘target points’ across land and sea, and results produced for both land and sea. ..............................................35 Figure 11 Geographical distribution of the effects of terrain height on views from the sea.. ....................36 Figure 12 Extent of horizontal view occupied by the sea at a 10 km distance, as measured by the proportion of the horizon for which the sea is visible. ...............................................................40 Figure 13 Extent of horizontal view occupied by the sea at a 6 km distance, as measured by the proportion of the horizon for which the sea is visible. ...............................................................41 Figure 14 Length of coastline visible within a 10 km radius of view. .......................................................42 3 Summary The conjunction of water and land provides unique character to landscape, and the importance of the presence of water in a scene has been documented by a number of authors (Shafer and Bush 1977; Wherrett, 2000). This strategic assessment of the coastal zone and characterization of 'Seascapes' around the Welsh coast uses a geographical analysis of the visibility of the coast to the landward and seaward side of the coastline. A Digital Terrain Model (DTM) is used as the basic input, from which four assessments of visibility are derived: 1. visibility of sea from the land; 2. visibility of land from the sea; 3. influence of land elevation on visibility from the sea; 4. and, a classification of coastal horizons. The results of the analyses are summarized below. Visibility of sea from the land The visibility of the sea from the land is based upon a 1 km x 1 km regular grid of points in a band 10 km seaward of the coastline. The number of sample points visible from every 50 m x 50 m cell inland of the coastline is recorded to provide a score of sea visibility from the land. The land from which the most extensive views of the sea are available is predominantly around the north and west coast (excluding Anglesey), extending from approximately Llandudno, west along the Lleyn peninsula south towards Aberystwyth and Fishguard. The coastline in the vicinity of Swansea also offers sites of high visibility of the sea, but the south- west coastal area, around Pembroke has few extensive sea views inland from the coast. The distribution of the visibility of the sea from the land with respect to the aspect of the terrain shows that the higher visibility levels are most extensive in a western arc between south-west and north-west. Visibility of the waters within 10 km of the coastline are calculated to be visible up to approximately 40 km