EurOCEAN 2000 - Vlaams Instituut voor de Zee

GEOTECHNICAL INVESTIGATIONS
The project is concerned to measure rock geotechnical properties that are likely to exercise
some control on platform development at the field sites. Schmidt hammer testing is being used
in the field, together with surveys of joint spacing and direction. Laboratory tests include
porosity and permeability determinations, point load and compressive tests. Due examination is
also being given to the physical and chemical weathering processes active on the platforms,
how they interact and combine, and are influenced by the geotechnical properties of the rocks
at the different sites. In addition, a study is being made of the erosive processes active on the
platforms, particularly abrasion, their relationship to the geotechnical properties of the rocks,
and their effects on rates and types of sediment production and platform development.
Abrasion mills are being used to simulate the action of the sea. In addition, small rock samples
(tablets) are being attached to the platforms so that their weight loss can be monitored (Moses,
2000).
PLATFORM MORPHOLOGY
Another objective of ESPED is to investigate the varying morphology of the shore platforms at
the study sites and relate it to the geotechnical properties of the rocks and sea conditions (fetch,
tidal range etc.). Tacheometric surveys are being made of the platform surfaces and profiles.
The intention is to construct a generalised morphometric map of each site showing the macro
surface relief as well as to prepare detailed maps of selected individual micro-relief features,
such as runnels and rock pools. The survey data will also be used to determine the width and
gradient of the platforms, and to identify breaks of slope. The structure of the runnel systems
will be analysed using network analysis. Calculations will be made of drainage densities,
stream frequencies and other morphometric variables.
CLIFF RETREAT MEASUREMENTS
A further objective of ESPED is to investigate the rates and manner of retreat of the sea cliffs
on the landward side of the shore platforms at the monitoring sites. By combining historic and
contemporary data it will be possible to reach broad conclusions concerning the relationship
between rates of cliff retreat and the rates of downwearing of the platforms. Existing maps and
aerial photographs have been analysed, also historic photographs and other archival material.
Different dates and scales of mapping in different EU countries has made cross-comparisons of
historical rates of retreat somewhat difficult, nevertheless the ESPED team has already
achieved a useful degree of transnational data harmonisation. At sites where the cliff faces are
retreating at the most only very slowly, time sequence photography is being used to determine
what changes, if any, are occurring. Standardised information is being collected on cliff
profiles, cliff erosion processes, and the contribution of cliff retreat to sediment inputs to the
marine environment.
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