Prestige: Slick drift observations and forecast
Accurate slick drift information is essential to efficient pollution recovery at sea and response on the coastline. From November the 13th, Cedre activated its cooperation agreement with Météo France, and started producing drift forecast charts for the Préfet Maritime of the Atlantic thanks to the Mothy model. At the request of SASEMAR, Cedre was also preparing a daily position chart of the hydrocarbons observed at sea. On November the 18th, a SASEMAR engineer joined the map-making unit situated in Brest for an urgent technology transfer. From this date, SASEMAR produced daily a position chart of the observed pollution.
On
motivation of the General Secretariat for the sea, the drift
forecast unit was soon turned into a national ‘drift’
committee with representatives of SHOM (Oceanographical
and Hydrographic Service of the French navy), IFREMER and
the maritime prefecture of the Atlantic. The committee members
met every day at Cedre’s to prepare a chart gathering
the nautical and aerial observations of the pollution and
the drift forecast available for four days. This chart was
accepted as the national reference. It has enabled to follow
the route of the hydrocarbons, to anticipate the threat
for the coasts and to guide the ships intervening at sea.
Drift forecast based on a Météo France computer
modelling
On
its side, from December the 2nd, the Portuguese Hydrographic
Institute produced a drift forecast chart every day. Finally
AZTI, the Spanish Basque Country technology institute for
fishing and food resources, contributed daily, from December
the 8th, a comprehensive memorandum which covered the northern
coast of Spain. It gathered a report and weather forecast,
the slick evolution, the French drift committee forecast,
its own forecast and the drift of the buoys dropped by the
institute in the midst of the main fuel accumulations observed
at sea.
Any
time discrepancies appeared between the different forecast
charts. The used reference data were compared through telephone
and email exchanges, to produce the best possible information,
as a clear-cut demonstration of the advantages of direct
cooperation between national institutions. The location
charts and the forecast were established from aerial observations
made by planes and helicopters, from observations made by
intervention ships and by the monitoring of the surface
or subsurface buoys. These buoys have been implemented directly
by SASEMAR, SHOM and AZTI or in the scope of SASEMAR/Cedre
and AZTI/Cedre cooperations.
For the slick location and
the guiding of the vessels towards the intervention areas,
the fishermen’s guild of the Basque Country adapted
the method they use to locate fish schools. A plane covered
the area by going back and forth perpendicularly to the
coast, pointing out on the GPS system the observed hydrocarbon
accumulations. Then the headquarters visualized on a computer
screen the different spots observed and the ship location
on the scene of the action. Next, they only had to guide
by satellite phone, ships which were the nearest of the
work areas.