Environmental Engineering Reference
In-Depth Information
Fig. 16.12
Sensitivity test of induced beach profile changes to selected morphodynamical time step: divergence
(
) 0.076 s; (——) 6 s; (-
-
) 100 s. SWL, still water level.
process. Gaining an understanding of the model
results from an analysis of their sensitivity to
changes in model parameters gives the engineer
a feeling for the robustness of values chosen for
any design calculations.
and accuracy of analysis that sits behind them
(Meadowcroft et al. 1995; Environment Agency
1996; Hall et al. 2003).
As illustrated in Figure 16.13, the components
are:
.
the cliff instability and erosion process, i.e. the
mechanisms and rate at which it might occur
(definition of the hazard);
.
any resistance to cliff instability and erosion, i.e.
coastal protection and slope stability measures
that slow erosion (modification of the hazard);
.
the location and value of the asset(s) of interest
(the risk).
Case Study: Risk Assessment of Cliff Erosion
Successful management of the coast requires a
clear understanding of the risks of coastal erosion
and instability. This section outlines a risk assess-
ment procedure that was developed for local au-
thority engineers to use for decision support in
shoreline management, and which can run on a
personal computer spreadsheet program. In this
context, decisions have to be made that have
practical consequences. Very often, the luxury of
waiting many years to compile detailed measure-
ments is not available, information is limited
and local knowledge and engineering judgement
can provide valuable input. The methodology
presented here is based on the source-pathway-
receptor risk model introduced by DETR (2000).
Each component has a number of factors that
require consideration and a range of associated
techniques, depending upon the degree of sophis-
tication of the analysis.
Components of the methodology
One single approach is adopted here irrespective
of the scale or data. It comprises three basic
components, the only difference being the level
Fig. 16.13
Components of the methodology.
