water quality parameters, supplemented by
intermittent measurements of the sand
concentration.
The data collected will form the basis for the
current research into the food chain, geomor-
phology and the connection between nutritious
substances and biomass. This article describes
the operation of the fully automated measuring
station.
The research vessel 'Argus'
Ever since the department of Environment
was set up in the seventies as part of the
Delta Service, research had been carried out
into the water quality of the coastal waters
and of the lower river estuaries. These
measurements are conducted mainly from
specially equipped measuring vessels.
The 'Ventjager', de 'Delta' and the 'Argus'
followed in succession. This article is mainly
concerned with the 'Argus'. This ship carries
out its measurements by using a water
sampler which is lowered into the water and
which measures while the ship is in motion.
The signals are entered into an on board
computer. The ship is also equipped with
three laboratories for processing water and
bed samples. The equipment includes a C14
isotope laboratory which is kept carefully
isolated.
The 'Argus' has an extremely advanced
navigation computer at its disposal, which can
store the nautical data on the entire research
area. There is a great demand for the facilities
which the 'Argus' has to offer.
Removal of ice in the northern Delta
estuaries
Considerable changes have occurred in the
hydraulic regime of the northern Delta
estuaries as well as in the formation and
removal of ice in winter and spring as a result
of the closure of the Volkerak and the Haring
vliet. The process of ice formation is occurring
more rapidly when, for example, a running
river like the Haringvliet becomes a semistag-
nant body of water due to reduced water
flows across its depth. This causes the water
surface to freeze much quicker. On the other
hand the effect of the dumping of cooling
water into the estuaries is noticeable, as ice
formation only occurs at low air temperatures
and rapidly disintegrates.
The decision as to whether to break the ice is,
in the first instance, in the hands of the
Rijkswaterstaat. Beyond this measures may be
taken for the removal of ice along certain river
440
branches and as a last resort by making usi of
the Haringvliet sluices.
An information processing system for
shipping in the southern Delta area
The procedures involved in passing throug a
lock have been greatly simplified with the
introduction of an information processing
system for the large locks in the southern
Delta area. Several stations for the regulat on
of water traffic have also been included in he
system.
The Kreekkrak locks serve as the central
computer centre. Data on a ship passing
through the system are required only once
and include name, loading capacity, type,
depth, load, origin and destination of the
vessel. These data can be stored and sign; led
through from lock to lock. In this way the I »ck
master can make the necessary arrangerm nts
for the lock chamber in advance of the shi )'s
arrival. Similarly the water authorities can
estimate the traffic load on the different
routes. Lists of dangerous pollutants can t e
made and statistical data obtained. The cc its
of installing the system and of five years
operation amount to around 5 million guili ers
including V.A.T.
Future development of the mud flat area of
the Oosterschelde
Extensive research has been carried out ir o
the morphological processes associated v ith
the development and breakup of mud flat: in
an intertidal area. This article presents the
final conclusions of this research. General y
speaking mud flats build up in the lee of tl e
dykes or dams. Since 1950 there had bee i
little new formation of mud flats as land
reclamation works have practically reached a
standstill. At present the mud flats are mc e
often being broken up, and this phenomenon
will continue after the storm surge barrier ras
come into use although to a lesser extent
However, some increase in the mud flat
formation is expected in the neighbourhoc d of
the compartment dams.
A study of the extent of the damage causi d
by the temporary closure of the barrier to he
mud flats will be included in the BARCON
project.
