FASE A: VISIÓN DE LA ARQUITECTURA

Movement of oil from fast known position (A) to predicted position 3 days later (B). Wind speeds of 25 knots and current speeds of 0.5 knots prevail in the directions indicated. Arrow lengths represent distances applicable to movement during 24 hours. A cross-wind ladder search pattern over B is shown with a flight path separation of 5 miles, chosen witn regard to visibility.

Bh

also recommended to prepare a flight plan with the use of updated charts,in order to reduce the area of search and economics time and fuel.This is called a SYSTEMATIC AERIAL SEARCH or LADDER SEARCH, which is done across the direction of the wind.(See Figure 11>.2/

A .2 I d g n t i f y t h e p o s s i b l e quantity of oil spilled.

An oil spill changes with the passage of time becau­

se of the so called weathering effects.

EVAPORATION,can produce appreciated property changes« within minutes.Hours,weeks and months respectively are required before OXIDATION,DISSOLUTION and BIOLOGICAL ATTACK cause changes in an oil spill.The unevaporated oil spreads on the water and will emulsify to form a stable water-in-oil emulsion which can contain up to 80 percent of water.Thus,the amount of pollutant can be appreciably greater than the amount of oil spilled,and it is dif­ ficult to assess the thickness and coverage of floating oil at sea. The best form to calculate is by a vertical down on the oil aerial observation and the use of an instant picture.also,by the time expended in overflying the lenght and width of the affected area at

a constant speed.Example:

65seconds x 150knots/3fc00 sec.per hour=2.7n.m.length.

GSseoonds x 150knots/3600 sec.per hour=l.5n.m.width. 3/

This gives a total area affected of 4 square n.miles or 14 square kilometers.Then, with the help of the table before mentioned an knowing the state of the oil,it is really easy to

87

4.3 Identifi;_the_5ituatiQn.

The first aerial information is important in asses­ sing the situation on-board the vessel or vessels in the case of a collision.If there is fire on-board,or if there are injured people;

it is necessary first to control the fire and to rescue all the persons before start trying to control the oil slick and spill ,by dispersants 4/,or physical removal.Here,the Fire Brigade and the Red Cross play the most important role.These bodies need the coope­ ration from other bodies such as the National Guard Force,Coastal

*1 Patrols,tugs,and private vessels and boats (see page 65).

After assessing the right location of the spill,and

by the use of past records and observations in situ on sea state,- wind and current direction and speed,and other hydrologic and ocea­ nographic parameters,experts can make a forecast of the possible changes in the area of the spill and of the possible movement of

the oil spill.

If past records are not available,the experts must

try to predict the possible changes on the basis of their experien­ ce and the action must be carried-out aocordinly.At this stage,the CMI and the HD work and advice play the most desicive role;but their information and advice will be valuable for the length of the

operation.

Although,it is desirable that research should be carried-out in the following years in matters of hydrographic and oceanographic parameters determination along our coast and juris­ dictional waters,in order to have enough back-up information when

8 6

^ ^ iBiii.survgi

The spill surveillance on the open seas is recom- cnBnded with the use of a twin-wing aircraft and near the shore with

an helycopter.5/. The collection of data on wind and current,and also in the possibility of future changes,is very important and essential for the spill surveillance,because wind can move oil at 3% of its speed,while currents on the same proportion.

<« In the CONCAWE Field Guide the use of computer models is recommended for the prediction of the movement of oil spills.On Figure 12 the schematic spreading of an oil spill on the sea surface at a specific rate of speed and direction

is shown.

Aerial surveillance of the spill should be attempted as soon after dawn,in order to gain as clear a picture as possible on how the overall situation has developed during the night. Sur­ veillance flights should then be repeated as often as necessary, particularly if the conditions of the source of the spill and the weather change constantly.

A final surveillance flight should be made shortly before dusk.The use of video or film cameras is recommended.6/.

A .5 SamglBs_og11BctionitransBortatign_and_analysis.

Most of this section is elaborated based on the recommendations given by the IP Oil Pollution Analysis Committee in .its book Marine_Pgil.utign_by_Oil^, chapters 4 and 5.

Figure 12

Spreading of oil spilled on sea surface