Dipl. Biol. Sven Koschinski Fa. Meereszoologie, Nehmten HELCOM SUBMERGED 4 Tallinn, 12-14 April 2016
„Darüber hinaus 35 "Kleinladung" (1-5 kg) 30 Vernichtungssprengung Baltic Sea (Germany) Seeminen Bundeswehr Schönhagen Thousands of mine and 25 bomb explosions in WW1 and WW2 20 (Kiel Bight: ca. 3.000 15 explosions ), Intense combat 10 operations also in the Gulf of Riga, Irben Strait, 5 and Gulf of Finland (Wichert 2014) 0 2007 2008 2009 2010 2011 2012 2015
„Darüber hinaus North Sea (Germany) 80 70 Vernichtungssprengung 60 Seeminen Increase of mine and bomb 50 explosions in recent years 40 due to offshore wind farm 30 construction (cable laying and turbine installations) 20 10 0 2012 2013 2014 2015
Very high Maximum Extremely peak pressure short signal Injury relevant noise parameters pressure variation rise time Peak pressure of noise impulse Rise time of noise impulse from water pressure to maximum amplitude Maximum pressure variation Impulse duration Total energy content of the noise impulse Water saturated tissues behave Only short durations but just as water! total energy content impacts hearing MMS (2003): Explosive Removal of Offshore Structures, Information Synthesis Report, OCS Study MMS 2003-070, 181 pp.
Primary Blast Injury (PBI) heavy tissue damage (especially gas filled organs : lung, seal ears, intestines) Internal bleeding (especially brain and ears) damage and dislocation of ear bones, tissue damage in inner ear (cochlea) Foto: S. Dubpernel
Acoustic trauma Cochlea with physiologic effect: Organ of balance frequency selective basilar membrqane exhaustion of hearing sensory cells (TTS) damage of sensory • Low cells, nerve degeneration frequencies (PTS) Oval • High frequencies window Hearing nerve Photo: CSI, Woods Hole Oceanographic Institution
Distance Minimum distance in relation to charge weight (m) 6000 Thiele & Stepputat 1998: distance diver = 1500 * charge weight 0,18 5000 Serious injury 4000 3000 2000 Example Tethered mine (300 kg) 1000 0 0 100 200 300 400 500 600 700 800 900 1000 Charge weight(kg)
Audiogram of a human diver 20 dB noise reduction by Neoprene hood
263 kg TNT eq . SEL (dB) PBI (p ≥ 95%) SEL (dB) 1m below water PBI-Onset surface 1m above bottom PTS-Onset TTS Increased danger close to the sea bottom! In the North Sea, harbour porpoises mainly feed on bottom-living fish species! aus: von Benda-Beckmann et al. 2015
• 88 UW-explosions in NL 2010-2011 • Charge weight 10-1000 kg (most often 125-250kg) • Noise measurements up to 2 km distance at various depths (7 detonations of 121 and 263 kg, water depth 26-28m, sand): 164 179 190 203 dB • Modeled source level (SEL) relative to charge weight • Propagation model improved with noise measurements • Analysis of effect radii and harbour porpoise density (spring1.34, summer 0.6 Ind./km²) Graph taken from: von Benda-Beckmann et al. 2015 (modified)
Number of harbour Number of impacts (NL, 88 explosions per year) porpoises (single explosion) Un- All near All near All near All near Ø Ø weighted surface bottom surface bottom threshold (SEL) Blast wave induced ear 203 0 1 1 1 119 60 trauma very dB likely Permanent 190 hearing loss dB 2 27 15 205 2.362 1.283 very likely Permanent 179 hearing loss dB 18 106 62 1.584 9.318 5.451 increasingly likely Noise induced 164 TTS very dB 190 448 319 16.721 39.413 28.067 likely Data taken from : von Benda-Beckmann et al. 2015 (modified)
Air bubble curtain for shock wave reduction (20 m depth, Heidkate, Baltic Sea) r=70m Tethered mine: 350 kg Air volume stream: 1m³/m*min www.hydrotechnik-luebeck.de
Big bubble curtain (BBC) for shock wave reduction Pressure measured inside BBC In good agreement with literature data Pressure measured outside BBC All 3 mine explosions with BBC In mine 4 incomplete BBC reduction in peak pressure: 19 dB - 6 dB - 16 dB Noise propagation model -6,8 dB per doubling of distance: reduction in peak pressure results in reduction of injury radius by 86% - 46% - 80%, Noise propagation model -4,5 dB: 95% - 60% - 91% Schmidtke,E. Schockwellendämpfung mit einem Luftblasenschleier zum Schutz der Meeressäuger. (2010). DAGA conference 2010 Berlin, Germany
Mitigation measure 1: deterrence by ~2 km Number of harbour porpoises (single explosion) Mitigation measure 2: Un- All near All near Ø reduction of effect radii by ~ 80% weighted surface bottom threshold (SEL) Blast wave induced ear 1 203 dB 0 1 1 0 trauma very likely Permanent 190 dB hearing loss 2 27 15 0,6 very likely Permanent 179 dB hearing loss 18 106 62 2,5 increasingly likely Noise 164 dB 319 induced TTS 190 448 13 very likely from: von Benda-Beckmann et al. 2015 (modified)
Without mitigation 50 Assumption: animals are near bottom 48 46 44 42 40 38 36 34 32 30 28 26 Blast wave induced 24 ear trauma very likely 22 20 18 Permanent hearing 16 loss very likely 14 12 10 Permanent hearing 8 loss increasingly likely 6 4 TTS very likely 2 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
100% deterrence up to 2 km 50 48 46 44 42 40 38 36 34 32 30 28 26 Blast wave induced 24 ear trauma very likely 22 20 18 Permanent hearing 16 loss very likely 14 12 10 Permanent hearing 8 loss increasingly likely 6 4 TTS very likely 2 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
100% deterrence up to 2 km 50 + reduction of effect radii by 80% 48 46 44 42 40 38 36 34 32 30 28 26 Blast wave induced ear trauma very likely 24 Permanent hearing loss very likely 22 Permanent hearing loss increasingly likely 20 TTS very likely 18 16 14 12 10 8 6 4 2 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
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