Reliability analysis of flood embankments taking into account a stochastic distribution of hydraulic loading

Flooding is a worldwide phenomenon. Over the last few decades the world has experienced a rising number of devastating flood events and the trend in such natural disasters is increasing. Furthermore, escalations in both the probability and magnitude of flood hazards are expected as a result of climate change. Flood defence embankments are one of the major flood defence measures and reliability assessment for these structures is therefore a very important process. Routine hydro-mechanical models for the stability of flood embankments are based on the assumptions of steady-state through-flow and zero pore-pressures above the phreatic surface, i.e. negative capillary pressure (suction) is ignored. Despite common belief, these assumptions may not always lead to conservative design. In addition, hydraulic loading is stochastic in nature and flood embankment stability should therefore be assessed in probabilistic terms. This cannot be accommodated by steady-state flow models. The paper presents an approach for reliability analysis of flood embankment taking into account the transient water through-flow. The factor of safety of the embankment is assessed in probabilistic terms based on a stochastic distribution for the hydraulic loading. Two different probabilistic approaches are tested to compare and validate the results.