Analysis and Ranking of the Acoustic Disturbance Potential of ...

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Report No. 6945 BBN Systems and Technologies Corporation The SNC ratings for the area show that the seismic array dredge, tug/barges and outdrives are the dominant sources with small craft, represented by the "whaler", and dredges rating as strong secondary sources. The review of marine mammal distribution in Section 2 showed that gray whales and walruses are important species in this area during the late spring and summer season. These species were used together with the five important sources determined above as the basis for the SER analysis shown in Table 5.6B, and illustrated by the graphs in Fig. 5.4A. The results of the SER analysis show that, in this region as well as in the Chukchi, gray whales are potentially the species which may be most influenced by the noise sources. In this case the seismic source shows the most potential for causing reactions with tug/barge operations having the second highest SER rating. The SER ratings for the outdrives and the tugs are strongly influenced by assumptions about the number operating. The assumed values are based on general information from the region but are not derived from specific on-site data. The SER values for walrus while not as high as those for gray whales, show a moderate potential for acoustic influence since the SER values are generally more than 50 dB higher than the SNC values for the input sources. The seismic array again has the highest SER rating. This conclusion is subject to revision if hearing data for the walrus become available since it is based on the assumption that walrus hearing characteristics are similar to those for California sea lions. The results of the model analysis for the late fall - early winter conditions in Norton Basin are shown in Table 5.7A. An icebreaker source has been added to the group of sources considered in the previous analysis. The numbers of the multiple sources operating have been reduced to reflect the probable seasonal effect. The resulting SNC ratings show that a seismic array retains its dominance followed by the icebreaker, coastal dredge, tug/barges, and outdrives. The estimated reduction in the number of outdrives and tugs operating has reduced their SNC ratings to less than that of the dredge. Important species present in the area during the late fall - early winter season are ringed seal and walrus. These species have been used together with the dominant four sources listed previously as the basis for the SER analysis (the SER results for outdrives are expected to be similar to those for the . tug/barges). The results, presented in Table 5.7B and in the graphs in Fig. 5.4B, show that the highest rating is for the ringed seal - seismic array encounter, with lower values occurring for the ringed seal - icebreaker and ringed seal - dredge encounters. The ringed seal - seismic array encounter may not occur very frequently in the real world because of the need for seismic vessels to operate well clear of ice covered areas as opposed to the propensity of ringed seals to seek out ice-covered areas. The ringed seal - icebreaker encounter, with a relatively high SER rating, is much more probable and the ri2ged seal - dredge encounter less likely. The SER results for walrus show a moderate interaction potential for the seismic array and icebreaker encounters which are lower than the ratings given the ringed seal encounters. The area SER ratings for all species are based on assumed density values and may be subject to revision when more information becomes available.
Report No. 6945 BBN Systems and Technologies Corporation TABLE 5.6A STANOAROIZEO NOISE CONTRlBUTlOI IIQ)EL, Norton Basin Pluming Area, Surfwe Layer Condition Ref. areas used in node1 (W2): Total overall, 118000 ; Coastal (c), 3310 ; fishing (f), 21600 ; Airports (a), 144 Ref. R-, 300 n; Max. Effutive Range; ahip, aircraft (kn)- 4 0.5 (e - atintad) Ref. 300 n Wov.Srce.Corr. flue. Equiv. Encntr. Exp. OYC Ratings source Typo Speed Oafrunt W, Hz Max l/3 0ct.H~ 0.W WJI 1/3 Area TravTia Corr. Level Prob. Nu. 0.M Nx 113 (kt$) fain lu Ls1,a frq. L12.8 Lr1.a Lr2.a -,dB Tt/lr Tf/Tr 1q.a Pe N WC1.a WCZ Tug/Barge (c) mmg 10 Twin Outdrv.(c).ovng 20 13' Haler (c) .ovng 20 B 737-200 (a) nwsn 400 C r s 172 ~ (a) mmg 100 krSM 172 (C) .ovng 100 Dredge (B)l)(c) fixed Dredge (AQ) fixad Drillship fixad 20 800 174 63 167 131 124 0 1 1 13! 8.5E-06 1 80 73 e fciric Array ~OH~O 5 20 160 216 SO 210 1lJ 167 -9 0.43 0.005 137 1.5E-04 1 W 93 TABLE 5.68 - atintad vatu (c) - coast01 area source STANDAROIZEb EXPOWRE RATING WEL, Norton Basin Plming Area, Surfue Layer Condition Source Informtion fra SNC llo61, Ref. Rmge - 300 l SOURCE Dairunt BY, a fSh Seismic Array 20 160 Seirnic Array 20 160 Twin lktdr.(c) 40 16000 Twin Outdr.(c) 40 16000 Tue/Barga (c) 100 12500 Tllp/Barg. (c) 100 12500 Oredoe (W)(c) 80 800 O~.dg. (BI1)(C) 00 m 13' Uhaler (c) 630 8000 13' Haler tc) 630 8000 ax in at Fs,Hz Lr2,B 50 167 50 167 500 113 500 113 6M 119 630 119 loo 124 100 in bow 110 coo0 110 NO. SNCl N a e* w e 1 w l 10 97 e 10 97 e 3 97 3 97 e 1 9 5 l 1 93 15 91 l 15 91 RECEIVER spcin (1) PK. Ualru Gray UhaLe PU. UakM Gray Uhale PK. Valru Gray Hale PU. y . L M Gray Hale Pu. Wlru Gray Uhale Hearing BY, kHz frl frh Fr e e e 0.7 30 15 e e l 0.09 9 0.7 e e l 0.7 30 15 e e e 0.09 9 0.7 e e e 0.7 30 15 e e e 0.W 9 0.7 e e l 0.7 30 15 e e l 0.09 9 0.7 e e e 0.7 30 15 e e l 0.09 9 0.7 Sensitivity sm,e ss,a e e 80 80 l e 40 41 e l 80 80 e e 40 40 e l 80 80 l e 40 40 l l 80 80 l l 40 40 l e 80 80 e l 40 40 a Area e 179 e 205 e 155 e 171 l 157 e 174 e 143 e 164 e 140 l 154 Note (1): Hearing characteristic for California sea Lion used for Pacific walrus. (2): Density valw for wlru btmimd by d*.rvatim for the Mom area (ut. 40 knA2)
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A BEAUFORT SEA B U WCH SEA CHOPEaAS
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Report No. 6945 L 1 A. Baird's Beak
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A BEAUFCRT SEA B CHW(CH SEA CHOPEBA
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A BEAUFCRT SEA BWKQIYA DrnTONBAsw E
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A BEAUFORT SEA BCHlKCHSEA CHaeEansr
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on the ice. The single calves remai
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A 0EAUFaAT SEA BCHJKCH 9 A CHaPE BA
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BCmrcCHSEA CHOPEBnsw 0 NORTON 0Am E
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.. A BEWORT SEA B WKCH SEA CH)PEBAS
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FIG. 3.2 NOISE SPECTRA IN SHALLOW W
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Adapted From K.H. Jacob (1986) Cali
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FIG. 3.8 ESTIMATED OVERALL SOUND LE
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FIG. 3. Q UNDERWATER NOISE SPECTRA
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FIG- 3.1 1 STATISTICAL ANALYSIS OF
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FIG- 3-12 STATISTICAL ANALYSIS OF C
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-- Alr Gun Array + Vlbrosels -* Ice
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FIG. 3.14 REPRESENTATIVE SHIPS AND
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~ -- -- FIG. 3.1 7 REPRESENTATIVE R
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FIG. 3-18 REPRESENTATIVE CULTURAL S
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FIG. D. 1 HUMAN VOCALIZATION AND AU
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FIG. D. 3 ESTIMATED HEARING CHARACT
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