Global sensitivity analysis of dike stability under maximum static
groundwater heads
Abstract
With a large network of dikes that in the future will protect up to 15%
of the world’s population from flooding, more extreme river discharges
that result from climate change will dramatically increase the flood
risk of these protected societies. Precise calculations of dike
stability under adverse loading conditions will become increasingly
important, though the hydrological impacts on dike stability,
particularly the effects of groundwater flow, are often oversimplified
in stability calculations. To include these effects, we use a coupled
hydro-stability model to indicate relations between the geometry,
subsurface materials, groundwater hydrology and stability of a dike
regarding soil slip and basal sliding mechanisms. Sensitivity analyses
are performed with this model using a large number of parameter
combinations, while assessing both the individual sensitivity as
combined effects. The analyses show that the material type of the dike
and its slope are the more important parameters influencing the
stability, followed by the shallow subsurface type and dike crest
elevation. The material of the dike and shallow subsurface is
additionally important, as a change towards sandier material can either
result in either an increase or a decrease of the stability. A database
created by an extensive Monte Carlo analysis provides further evidence
for these relations and is used to estimate failure probabilities for
dike stretches that have not been assessed in detail. Despite the use of
a simplified model, not including small-scale heterogeneity, remaining
soil strength and transient groundwater flow, the application of the
method to a case study proves its applicability.