PROTECT project
PROTECT
The erosion of hard rock cliffs is inevitable and to-date it has been considered to be relatively unpredictable. A large proportion of the European coastline is subject to erosion and cliff recession. This dynamic process continually changes the hydrogeological and stress regimes, exposes fresh geological features and materials to changes in environment and stress. The assessment of cliff recession is an important factor in hazard assessment, conservation, amenity, and land-use planning. Hard rock cliffs erode through catastrophic collapse along pre-existing discontinuities in the rock mass. These may be ancient faults or fractures, orientated at a variety of angles to the cliff face, or relatively new tension fractures formed during cycles of cliff recession, sub-parallel to the cliff face. Glacial, periglacial and weathering processes, have frequently deposited a layer of reworked rock and soil onto the bedrock. This factor, and the inaccessibility of many cliff sections, makes the direct mapping of discontinuities in the bedrock difficult. The objectives of PROTECT are:
- To develop predictive tools, which will identify sections of cliffed coastline, that are approaching a state of imminent collapse and allow accurate predictions to be made of the timing of the collapse. This objective will be achieved through a number of scientific and technological objectives.
- A non-invasive geophysical technique will be developed to measure the changes in physical properties of the rock mass near a cliff edge as the cliff changes from a stable to an unstable state. The technique determines the change in apparent resistivity with orientation of the measurement within a volume of the rock mass of approximately 145,000 m3. These variations are determined by the fracture network within the rock mass and changes with time will indicate changes of tension within the fractures. Increased tension indicates a weakening of the rock mass. The time scales of such changes and the extent of the affected zone near the cliff edge, will be determined.
- A new methodology will be developed to monitor unstable cliff sections and predict the initiation of a fall through monitoring of micro movements along pre-existing cracks. These techniques are applicable to cliff sections that are in a state of collapse and will assist communities threatened by cliff erosion. Tuned microseismic methods will be able to monitor a coastline of 400 m length to a depth behind the cliff face of 40 m. The minimum crack surface along which movement can be detected will be 10 m2.
- To contribute to the wider goal of understanding the physical properties of the rock mass, which leads to unstable cliffs. Data collected and collated during the project will be compared against the parameters being measured to predict cliff collapse. This will further the understanding of cliff collapse processes. The data collected will also enhance existing databases on the physical properties of coastal sections.
- To work with and be guided by the user community. This will involve ensuring development is adapted to the users requirements. This will enable them to:
Issue informed hazard warnings in areas of cliffs.
Make more informed land-use planning decisions in the coastal zone.
Maximise the use of the cliffed coastline as an amenity.
Develop informed conservation plans.
- Advance the technology sufficiently so that guidelines for it's implementation by coastal managers and/or development into an industrial prototype can be made. This will ensure that the outcomes of the project are utilised in the future.
Contract EVK3-CT-2000-00029
