9.6.2 Operational Phase 129. There are very few reported measurements of wind turbine noise and much of the data that is publicly available is summarised in Wahlberg and Westerberg (2005) and Madsen et al. (2006), with Tougaard and Henriksen (2009) providing a more recent update.
130. Underwater noise from an operational turbine mainly originates from the gearbox and the generator and has tonal characteristics (Madsen et al. 2005; Tougaard and Henriksen 2009). The radiated levels are low and the spatial extent of the potential impact of the operational windfarm noise on marine receptors is generally estimated to be small and turbine noise has generally been considered unlikely to result in any injury to marine mammals (e.g. Tougaard and Henriksen 2009) or fish (Wahlberg and Westerberg 2005). Besides the sound source level the potential for impact will also depend on the propagation environment, receptor’s hearing ability and the ambient sound levels.
131. Marine animals may perceive the radiated tonal components where they exist above the ambient noise levels, which may result in a behavioural response of the receptor or lead to a reduced detection of other sounds due to masking. Previous studies have reported behavioural response to only be likely to occur at close ranges from the turbine (a few metres for fish and harbour porpoise (Wahlberg and Westerberg 2005 and Tougaard and Henriksen 2009, respectively) and possibly up to a few hundred metres for seals (Tougaard and Henriksen 2009). Touggard and Henriksen (2009) further show that even masking from operational noise is unlikely to impact harbour porpoise and seal acoustic communication due to the low frequencies and low levels produced.
132. A relatively recent study, by Scheidat et al. (2011), has reported an attraction of harbour porpoise to an operational Dutch windfarm site where abundance was higher within the windfarm compared to a similar environment in near-by areas. This was assumed to be due to decreased fishing and vessel activity and increased food availability (Scheidat et al. 2011). The authors, however, caution against generic transfer of these results to other windfarms as the response is likely a net result of various factors, which may differ between scenarios. A similar study at the Nysted windfarm for example showed only a partial recovery in harbour porpoise abundance two years into the operational cycle of the windfarm (Tougaard et al. 2005). It should also be noted that the response of a receptor will depend on its physical state and its presence may depend on the drivers for it being in the area and may also result from a change in the environment or habitat.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm Appendix 9.1 Underwater Noise Modelling 61
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150