[MARMAM] computer simulation of sound radiation from explosion needed

Sven Koschinski marine-zoology at t-online.de
Thu Dec 7 11:01:20 PST 2006


Dear MARMAMers,
in the German part of the Baltic Sea 120 large explosives (torpedo
heads and sea mines of World War II) have been found a few years ago.
In October 2006, authorities started to detonate these. No safety
regulations for marine mammals have been considered by the ministry
of the environment. After protests of 3 NGOs, ministries agreed on
using deterrent sound in order to scare harbour porpoises away.
Individuals of the rare eastern Baltic population (probably less than
600 animals left) may migrate through or even stay in the area during
winter. We doubt that the proposed deterrent is sufficient to scare
marine mammals out of the danger zone.

33 explosives have been destroyed so far. Up to 90 explosions are
expected during the rest of this winter.

These explosions have also implications for further detonations
during the construction of the Russian/German Baltic Sea gas
pipeline. Therefore we demand a safety protocol for marine mammals.

We are unsure about the exact dimensions of the safety zone. We
proposed a safe level at the marine mammal ear of 160 dB re 1µPa
similar to safety regulations of the NATO Undersea Research Center
with respect to sonar. Can anybody of you simulate sound radiation
from an explosion of 350 kg TNT at the bottom of 10 m water depth in
Kiel Bight (sandy bottom, water temperature 9 degrees Celsius,
salinity 12 PSU, mixed water body, gentle slope, distance from coast
2.5 km)?

For the authorities it would pe possible to get such a calculation
from the German Navy, but they would not do such a calculation for an
NGO. And authorities refuse to have a simulation done.

We are aware that there is no simple calculation using formulas from
Richardsons "Marine Mammals and Noise" because much of the energy
will be lost through the surface. And we have no idea how to
determine what energy radiates horizontally. Who can help?

All the best,

Sven

Dipl. Biol. Sven Koschinski
Kühlandweg 12
D-24326 Nehmten
Tel. ++49- (0) 4526 - 38 17 16
priv. ++49- (0) 4526 - 38 08 08
marine-zoology at t-online.de






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