4
DELTARES, JANUARY 2014
D
eltares is extending its research effort looking
at peat strength. The new research will build on
the foundations established by a field trial which
demonstrated that peat is actually much stronger
than previously thought. An accurate picture of peat strength
is important for dike design.
The research began to answer questions relating to the
upgrade of the Markermeer dike in North Holland. The
subsurface below that dike is peat and, by and large, it fails
to meet current safety standards. When the dike upgrade
was being planned in 2011, the water authority (the
Hoogheemraadschap Hollands Noorderkwartier) decided a
study was needed to check whether the current calculation
method for peat, which is being used to design the dike
upgrade, uses a correct value for the strength of peat. Experts
have had their doubts about this value for some time. The
first field study near the Markermeer dike did indeed show
that peat is stronger than indicated by the present standards.
The follow-up study will focus on implementing the results of
the previous study, with the aim of developing a new design
approach for the dike. This will have a direct impact on the
upgrading of the Markermeer dike: a clearer picture of peat
behaviour could cut the cost of the upgrade operation.
SIMPLE MONITORING SYSTEM
IMPROVES WATER QUALITY
DELTARES
IN BRIEF
In an alliance with SorbiSense
and Alterra, Deltares devel-
oped a simple monitoring
system that records both
flow rates and the amounts
of substances present in the
water. The Flow-Cap makes
it possible to identify more
precisely the sources of sub-
stances like nitrates in agri-
cultural areas. The Flow-Cap
is positioned in agricultural
drains or discharge pipes ex-
iting greenhouses and it reg-
isters the amount of contam-
ination. The National Institute
of Public Health and the
Environment (RIVM) and the
Productschap Tuinbouw (the
Dutch horticulture branch
organisation) had ask­ed for
a monitoring system of this
kind to improve the quality of
research looking at how ag-
riculture impacts the quality
of surface water. Until now,
there was no easy way of
measuring levels of pollut-
ants exiting an agricultural
drain or discharge pipe with
the discharge water.
The Flow-Cap ensures that a
fixed proportion of the total
discharge flows through a
SorbiCell. This SorbiCell,
which has been patented
by Sorbisense, records the
amount of the target sub-
stance and the size of the
water flow. The SorbiCell is
analysed in the laboratory to
determine the pollutant load
during the installation period.
The monitoring system does
not use any electricity, and
installation and removal are
straightforward so it is easy
to use in numerous locations.
PHOTO: HOLLANDSE HOOGTE
The Markermeer dike in North Holland is centre-stage
during research looking at the strength of peat.
The Flow-Cap allows for
a clearer picture of the
impact of agriculture on
the quality of surface
water.
PHOTO: DELTARES
PEAT STRONGER
THAN EXPECTED