Hydro-ecological relations in the Delta Waters

apart from upstream purification;
- h natural estuaries, azeas of sedimentation - lnud flats and salt
marshes - are usually the most valuable areea. Theg aw accardingly
exceptionally susceptible to pollution, as in the case of 'Het Land
van Saeftinghe'. Attempts to clean upstream should therdore at the
very leasr be directed at safegwding the natursl richer; of these
sedimntatlon areas;
- Compartmentalizatiun eau be used to confine accumulation of
pollutants to a rescricted, manageable area. This protects othe~
areas from pollution &nd accompanying problems. Wiahent
compartmentalization a camiderable parr of the severely
coutamina0ed silt, n w present as sedimentation in the Hollands
Diep and Haringrrliet, would have entered the coastal waters and the
Wadden 6ea. So compartmentaliration could also be applied
especially for this purpose, harever, as an interim measure in
combination with efforts to clean up pollution.
3 DOWNS'J!XUM FRESH WATER EUTROPRZCATION
Besides being ezceptianally vulnerable EO pollution, the semi-stagnant
freshwater basins sltnated do*astream are also increasingly
susceptible ta eutrophication. iieretw, upstream purification is
necessaxy for responsible compartmentalizatian. At the same time,
however, the scope for management increases:
- A major factor affecting heightened snsceptibility to
eutrophication is the increase in the residence time oi water. The
organization of the watemnanagement infrastructure, in such a way
that the residence times can be reduced to a euffioient degree, is
an important management aid;
- Eutrophication priaariLy resnlts from an excess aE nutrients. One
of the facters affecting the way in which nutrients paas thtcueh an
aquatic ecosystem is the latter's structure, and this creates scope
for esntrolling such systems, partioulazly in the early stages of
development, as in the case of the Zomeer, Ecological parasleters
must be set fsr the establishment and develop~nent of rich, divers
biocoenoses eharacteriscics of clear water rich in nutrients.