Case Studies - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 426

9.4.2.2 Data Collection for Model Implementation

Despite declarations that lagoon waters had been “monitored” by both Polish and
Russian environmental authorities for many years, the analysis of existing data
revealed that this monitoring actually provided very poor data to fit the model.
Parameters were neither measured regularly nor simultaneously. A typical situation
occurred in the administrative approach to lagoon monitoring, namely that one
parameter was measured one year and another parameter was measured the next
year. The frequency of measurements was usually three to four times per year;
these data can only be used to make rough evaluations of interannual dynamics.
These monitoring data combined with historical information 8 provided only a
general understanding of the processes taking place in the lagoon. Therefore, a
supplementary data collection program was undertaken.
All of the spatial characteristics of the lagoon were examined—configuration
of the coastal line, bottom sediment structure, lagoon bathymetry, and root veg-
etation areas. Historical information on lagoon bathymetry was compared with
current results, and it was determined that a general deepening of the Vistula
Lagoon had taken place. Following detailed study, it was subsequently found that
active wind resuspension processes promote the flushing out of sediment from
the lagoon and that the lagoon may even have a negative sediment balance. The
reason for this is the anthropogenic reduction of sediment loading, which is
accomplished by routing Vistula River discharge directly into the Baltic Sea via
other branches. 24
A short-term (2.5-month) field program of current measurements at 16 stations
in the lagoon together with four daily measurements of meteorological parameters
at five stations around the lagoon was conducted. The lagoon entrance was carefully
scrutinized, and variations in water level, salinity, and temperature were determined
hourly during this period. The data obtained were used for calibrating the hydrody-
namic module.
An 18-month-long data collection program was executed to gather data on
salinity, nutrients, and suspended sediment dynamics. Cruises around 22 points in
the lagoon ( Figure 9.4.3) were undertaken by both Polish and Russian research teams
monthly during previously agreed periods. Meteorological parameters, water level,
and water temperature were measured from two to four times daily at four locations
along the lagoon coast. In addition, salinity measurements were taken twice daily
at the lagoon entrance.
Information on nutrient loading was collected during the same period for the
main rivers and all wastewater discharge outlets. Loading estimations were done on
the basis of field measurement data and using theoretical estimations, which took
into consideration agricultural activity (a load of about 15 kg N/ha was estimated
for farmland with medium and intensive use of fertilizers, and a load of 6.1 kg N/ha
was estimated for minimum use), livestock, and population density. 20
The comparison of theoretically estimated data with measurements and eco-
nomic statistics from enterprises and environmental authorities revealed significant
variations in loading values. Loading information is a crucial part of data collection,
and errors in these data greatly exceed those in any physical data.