Ballast Water Management Decision Support System Model Application - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 262

(D-1 standard). Furthermore, BWE is still the only widely applicable BWM option
which should be used before certifi ed BWMS are installed and in operation on board
vessels (D-2 standard).
Ballast Water Exchange as a Blanket Ballast Water
Management Approach for the Port of Koper
BWE has limitations in its effectiveness and especially in its applicability in
semi-enclosed or enclosed areas. Ships in such areas usually sail within 50 NM from
nearest land, as well as in too shallow waters (<200 m depth), therefore according
to the BWM Convention they should not conduct BWE. As a result, unmanaged
ballast water may be discharged in ports (see Fig. 4 ).
The ballast water discharge data for the Port of Koper from 2005 were analysed
to assess (a) the number of vessels that would be able to conduct BWE on their
intended routes according to the BWM Convention, and (b) the quantity of ballast
water which would be discharged (managed versus unmanaged). As a result, in 2005
a total 448 vessels discharged 544,133 m 3 of ballast water in the Port of Koper.
It is most likely that only vessels from outside the Adriatic Sea are enabled to
conduct BWE, therefore only vessels that discharged ballast from zone 3 or 4 were
considered. Firstly, all source ports from zones 3 and 4 were identifi ed and connected
with intended shipping routes to the Port of Koper. This was done to identify which
of the intended routes would enable BWE according to the IMO requirements
(see Fig. 5 ).
The minimum distances needed to complete BWE were also taken into account
considering the quantity of ballast water to be exchanged and the vessels BWE
Fig. 4 Flowchart showing BWE options according to the BWM Convention. The references D-1,
B-4.1, B-4.2 and C-1 refer to Regulations of the BWM Convention. BW ballast water, BWEA
ballast water exchange area, BWRA ballast water risk assessment