The probabilistic assessment of small homogeneous UK earthfill dams affected by climate change; Precipitation

The focus of this research is on small, well-established, homogeneous earthfill embankment dams that are currently in use and whose performance was previously outside the Reservoirs Act 1975, but are now governed by the new Flood and Water Management Act 2010. Many uncertainties are associated with such structures, a situation that can lead to the threat of dam failure when extreme climate conditions develop. Therefore, merely carrying out a deterministic assessment for such structures is insufficient and more sophisticated models, which reflect uncertain conditions of the dam site are required. This research presents the new advanced probabilistic slope stability model with precipitation effects (APSMP) developed by integrating the First Order Second Moment method (FOSM) with the deterministic slope stability model with precipitation (ASMP) using sliding block formulation. For the purpose of this study, the selected precipitation scenarios (rainfall intensity and duration) are obtained from past Met Office rainfall records and by applying the latest probabilistic model for predicting future precipitation projections for the UK (UKCP09). It is demonstrated that by implementing APSMP the notional reliability and probability of upstream and downstream slope failure for small homogeneous earthfill embankment dams can be quantified. To reflect the critical conditions conducive to slope failure a benchmark has been developed, as a reference for comparison of the effect of precipitation on the notional reliability and performance classification of the embankment’s slopes. By considering the probabilities of failure collated from APSMP and their associated performance, the impact critical precipitation effects could have on the notional level of engineering risk associated with slope failure is also identified. Hence, the dam’s risk, as categorized by the Flood and Water Management Act 2010, can be reassessed in terms of engineering risk. From the results obtained using APSMP a more informed assessment of small homogeneous earthfill embankment dams using limited information, including the level of uncertainty associated with the available site data, can therefore be carried out. Such an approach is therefore well placed to support and enhance the decision making process when evaluating the likelihood of dam failure, its impact on infrastructure performance and public safety, especially in relation to future climate effects.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

City University London

Year dc:date.issued

2013

Author dc:creator

• Preziosi, Marie-Christine

• TA Engineering (General). Civil engineering (General)