Hydro-ecological relations in the Delta Waters

estuaries. The net freshwater load directly from the rivers Rhine and
Mwse is extremelp small (1% of the discharge). Tba Veerse Meer lagoon
eaperiences almost permanent stratiEicaeion, whereas the
Oreveliugenmeer has only a few deep channels, stratified during summer.
The Westerschelde and Oostersehelde estuaries are completely &ed
tidal systems.
Table 1
System parameters of the saline waters in the Swth-West
Netherlands, derived from Wollast, 1988, and Bokhorst, 1988,
for the Westerschelde; Projectgroep Balans, 191d8, and
Wetsteyn and Peperzak, 1988, for the Oosferschelde; Nienhuis,
1985, and De Vries, et al, 1988, for the Grevelingen: Daemen,
1985. and Stronkhorst. et al, 1985. for the Veerse Meer. Load
= direet water load from Rhine-Meuse.
reddenGB time (4)
bad h%-1,
tides
stFati£icatlan
extinct-.
(m-')
The Westerschelde is extremely turbid (extinction coefficient 0.5-7)
and the Grevelfngenmeor contains very clear water (extinction
coefficient 0.2- 0.5). with the Oosterschelde and Veerse Meer in
between.
The range in nutrient concentrations in the saline Delta waters differs
greatly (lfig. 5). The Oostersehelde and Crevelfngen reach only seldom
for N. P and Si; nutrient values frequently
values above 1 mg I-'
approach zero concantratione during heavy blooms of phytoplankton.
The Veersa Meet has higher maximum values for N and Si, but depletion
occurs during the growing season. The Westerschelde has far out the