Case Studies - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 432

June-August

km

30

%
10 to 20

20

0 to 10
− 10 to 0
− 20 to − 10
− 10 20

− 40 to − 30

30 to −

−75 to − 40

0

0 10 20 30 40 50 60 70 80

km

FIGURE 9.4.5 Spatial distribution of change (in percent) of average summer concentration
of chlorophyll a comparing scenario (3) to the basic solution for 1994. Negative percentages
correspond to reduction of chlorophyll concentration.

4. All urban and industrial sewage is collected and conveyed to the wastes-

water treatment facility. The first paper mill undergoes partial renovation.
The second paper mill is not renovated.

In 1996, scenario (1) had an implementation target date of 1998, whereas
scenarios (2), (3), and (4), which are extensions of the wastewater treatment in
scenario (1), were planned to be fully implemented by the year 2010. In addition,
different options for locations for the outlets from a new wastewater treatment facility
were analyzed.
The results of scenario simulations were evaluated by comparing each with the
reference basic solution for 1994. To condense the huge amount of information (a
“basic” solution as well as eight scenario solutions were obtained for each parameter
under study for each grid point in the lagoon for a 1-year period) the average seasonal
maps of difference between scenario and “basic” solutions were developed. The
example of such a seasonal map scheme is shown in Figure 9.4.5. Such a method
revealed the benefits of different parts of the lagoon from different loading scenarios.

9.4.2.7 Summary and Management Recommendations

Integrated management of the Vistula Lagoon is particularly difficult because it is
a transboundary area that faces multiple economic and environmental problems. In
the last several years pronounced efforts have been made to improve wastewater
treatment at the main point sources in the catchment area on the Polish side. The
improvement of water quality on the Russian side of the lagoon depended directly
on the reduction of urban sewage, including nutrients.
The need for a bilateral commission, with the possible participation of other
partners, is crucial. For example, because the Polish and Russian project 19 partners
often have their own points of view on critical issues, the responsibility of final
conclusions was assigned to a third partner, an expert team from Denmark. 20