NAI and WPM Assessment V5
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Appendix C No Active Intervention and With Present Management Assessment Cornwall and Isles of Scilly SMP2 NAI & WPM assessment Final Report Appendix C - i - February 2011 CONTENTS Page 1 WHITSAND BAY 1 1.1 Typical coastal evolution 1 1.1.1 Epoch 1, years 0 – 20 (2025) 1 1.1.2 Epoch 2, years 20 – 50 (2055) 1 1.1.3 Epoch 3, years 50 – 100 (2105) 1 1.2 Unit details – No Active Intervention 2 1.3 Unit details – With Present Management 2 2 WHITSAND BAY TO LOOE POINT 4 2.1 Typical coastal evolution 4 2.1.1 Epoch 1, years 0 – 20 (2025) 4 2.1.2 Epoch 2, years 20 – 50 (2055) 4 2.1.3 Epoch 3, years 50 – 100 (2105) 4 2.2 Unit details – No Active Intervention 5 2.3 Unit details – With Present Management 6 3 THE LOOE RIVERS 8 3.1 Typical evolution 8 3.2 Unit details – No Active Intervention 8 3.3 Unit details – With Present Management 9 4 LOOE POINT TO GRIBBIN HEAD 11 4.1 Typical coastal evolution 11 4.1.1 Epoch 1, years 0 – 20 (2025) 11 4.1.2 Epoch 2, years 20 – 50 (2055) 11 4.1.3 Epoch 3, years 50 – 100 (2105) 11 4.2 Unit details – No Active Intervention 12 4.3 Unit details – With Present Management 12 5 GRIBBIN HEAD TO BLACK HEAD 14 5.1 Typical coastal evolution 14 5.1.1 Epoch 1, years 0 – 20 (2025) 14 5.1.2 Epoch 2, years 20 – 50 (2055) 14 5.1.3 Epoch 3, years 50 – 100 (2105) 14 5.2 Unit details – No Active Intervention 15 5.3 Unit details – With Present Management 17 6 BLACK HEAD TO DODMAN POINT 20 6.1 Typical coastal evolution 20 6.1.1 Epoch 1, years 0 – 20 (2025) 20 6.1.2 Epoch 2, years 20 – 50 (2055) 20 6.1.3 Epoch 3, years 50 – 100 (2105) 20 6.2 Unit details – No Active Intervention 21 6.3 Unit details – With Present Management 22 Cornwall and Isles of Scilly SMP2 NAI & WPM assessment Final Report Appendix C - ii - February 2011 7 DODMAN POINT TO LIZARD POINT 25 7.1 Typical coastal evolution 25 7.1.1 Epoch 1, years 0 – 20 (2025) 25 7.1.2 Epoch 2, years 20 – 50 (2055) 25 7.1.3 Epoch 3, years 50 – 100 (2105) 25 7.2 Unit details – No Active Intervention 26 7.3 Unit details – With Present Management 33 8 HELFORD RIVER 42 8.1 Typical evolution 42 8.2 Unit details – No Active Intervention 42 8.3 Unit details – With Present Management 44 9 LIZARD POINT TO PENLEE POINT 48 9.1 Typical coastal evolution 48 9.1.1 Epoch 1, years 0 – 20 (2025) 48 9.1.2 Epoch 2, years 20 – 50 (2055) 48 9.1.3 Epoch 3, years 50 – 100 (2105) 48 9.2 Unit details – No Active Intervention 49 9.3 Unit details – With Present Management 59 10 PENLEE POINT TO LANDS END 70 10.1 Typical coastal evolution 70 10.1.1 Epoch 1, years 0 – 20 (2025) 70 10.1.2 Epoch 2, years 20 – 50 (2055) 70 10.1.3 Epoch 3, years 50 – 100 (2105) 70 10.2 Unit details – No Active Intervention 71 10.3 Unit details – With Present Management 72 11 LANDS END TO ST IVES HEAD 75 11.1 Typical coastal evolution 75 11.1.1 Epoch 1, years 0 – 20 (2025) 75 11.1.2 Epoch 2, years 20 – 50 (2055) 75 11.1.3 Epoch 3, years 50 – 100 (2105) 75 11.2 Unit details – No Active Intervention 76 11.3 Unit details – With Present Management 77 12 CARBIS BAY (ST IVES HEAD TO GODREVY POINT) 79 12.1 General coastal evolution 79 12.2 Unit details – No Active Intervention 79 12.3 Unit details – With Present Management 82 13 HAYLE ESTUARY 87 13.1 General estuarial evolution 87 13.2 Unit details – No Active Intervention 87 13.3 Unit details – With Present Management 90 14 GODREVY POINT TO ST AGNES HEAD 93 14.1 Typical coastal evolution 93 Cornwall and Isles of Scilly SMP2 NAI & WPM assessment Final Report Appendix C - iii - February 2011 14.1.1 Epoch 1, years 0 – 20 (2025) 93 14.1.2 Epoch 2, years 20 – 50 (2055) 93 14.1.3 Epoch 3, years 50 – 100 (2105) 93 14.2 Unit details – No Active Intervention 94 14.3 Unit details – With Present Management 95 15 ST AGNES HEAD TO TOWAN HEAD 97 15.1 Typical coastal evolution 97 15.1.1 Epoch 1, years 0 – 20 (2025) 97 15.1.2 Epoch 2, years 20 – 50 (2055) 97 15.1.3 Epoch 3, years 50 – 100 (2105) 97 15.2 Unit details – No Active Intervention 98 15.3 Unit details – With Present Management 102 16 TOWAN HEAD TO PARK HEAD 107 16.1 Typical coastal evolution 107 16.1.1 Epoch 1, years 0 – 20 (2025) 107 16.1.2 Epoch 2, years 20 – 50 (2055) 107 16.1.3 Epoch 3, years 50 – 100 (2105) 107 16.2 Unit details – No Active Intervention 108 16.3 Unit details – With Present Management 110 17 PARK HEAD TO TREVOSE HEAD 114 17.1 Typical coastal evolution 114 17.1.1 Epoch 1, years 0 – 20 (2025) 114 17.1.2 Epoch 2, years 20 – 50 (2055) 114 17.1.3 Epoch 3, years 50 – 100 (2105) 114 17.2 Unit details – No Active Intervention 115 17.3 Unit details – With Present Management 116 18 TREVOSE HEAD TO PENTIRE POINT 119 18.1 Typical coastal evolution 119 18.1.1 Epoch 1, years 0 – 20 (2025) 119 18.1.2 Epoch 2, years 20 – 50 (2055) 119 18.1.3 Epoch 3, years 50 – 100 (2105) 119 18.2 Unit details – No Active Intervention 120 18.3 Unit details – With Present Management 122 19 PENTIRE POINT HARTLAND POINT 125 19.1 Typical coastal evolution 125 19.1.1 Epoch 1, years 0 – 20 (2025) 125 19.1.2 Epoch 2, years 20 – 50 (2055) 125 19.1.3 Epoch 3, years 50 – 100 (2105) 125 19.2 Unit details – No Active Intervention 126 19.3 Unit details – With Present Management 129 20 ISLES OF SCILLY 134 20.1 Typical coastal evolution of the Isles of Scilly 134 20.1.1 Epoch 1, years 0 – 20 (2025) 134 Cornwall and Isles of Scilly SMP2 NAI & WPM assessment Final Report Appendix C - iv - February 2011 20.1.2 Epoch 2, years 20 – 50 (2055) 134 20.1.3 Epoch 3, years 50 – 100 (2105) 134 20.2 St Mary’s unit details – No Active Intervention 135 20.3 St Mary’s unit details – With Present Management 137 20.4 St Agnes and Gough unit details – No Active Intervention 141 20.5 St Agnes and Gough unit details – With Present Management 143 20.6 Tresco and Byher unit details – No Active Intervention 146 20.7 Tresco and Byher unit details – With Present Management 150 20.8 St Martins unit details – No Active Intervention 156 20.9 St Martins unit details – With Present Management 158 Cornwall and Isles of Scilly SMP2 NAI & WPM assessment Final Report Appendix C - v - February 2011 1 WHITSAND BAY 1.1 Typical coastal evolution 1.1.1 Epoch 1, years 0 – 20 (2025) The coast will continue to erode whilst retaining its current characteristics. Occasional landslides and rockfalls will cause cliff tops to retreat, and will deliver sediment to the foreshores. These processes will be driven by ongoing wave erosion of the cliff base, which will also form new areas of shore platform. The shore platform will be lowered by wave action, where it is not protected by beach material. The beaches will remain relatively stable, and will be fed by the larger sediments released by the ongoing erosion processes. A small acceleration in the rate of relative sea level rise will cause shore platforms to be slightly lower, relative to the mean sea level. The region of beach/ rock platform exposed above low water will become slightly narrower as the sea rise accelerates. This will allow slightly larger waves to arrive at the cliffs, increasing the severity of wave breaking. As a consequence the shore will retreat slightly faster than it has in the past 1.1.2 Epoch 2, years 20 – 50 (2055) The coast will continue to erode whilst retaining its current characteristics, as in epoch 1. A larger acceleration in rate of relative sea level rise will cause shore platforms to continue to fall, relative to the mean sea level. The region of beach/ rock platform exposed above low water will narrow. High tide will reach the cliff toe more frequently and this will allow larger waves to strike the cliffs, increasing the severity of wave breaking and raising recession rates. As a consequence the proportion of the cliff face comprised of active landslides will tend to increase. This will supply more material to the beach, which will mitigate, although not prevent, the narrowing of the intertidal zone. 1.1.3 Epoch 3, years 50 – 100 (2105) The coast will continue to erode whilst retaining its current characteristics, as in epochs 1 and 2. Continued acceleration of the rate of relative sea level rise will cause shore platforms to continue to fall, relative to the mean sea level. The region of beach/ rock platform exposed above low water will continue to narrow. High tide will reach the cliff toe more frequently and allow larger waves to strike the cliffs with more energy.