When analysing the slope stability of levees, the soil mechanical parameters of the saturated and unsaturated cross-sectional areas are the key influencing factors. Thus, prediction of the seepage line is necessary. In practice, steady-state boundary conditions are typically assumed, where the seepage line reaches the maximum elevation within the levee. This scenario leads to conservative, potentially oversimplified safety assessments, reflecting the awareness that the actual level of safety is not fully known and acknowledges the inherently dynamic rather than steady-state nature of flood events. This study proposes a novel approach to enhance the safety assessment of homogeneous levees by accounting for the dynamic evolution of phreatic lines over time. By considering transient seepage flow and incorporating key flood hydrograph parameters, such as rising or peak duration, and using an analytical estimate of the transient seepage line, this method allows the practical application of risk-based design in flood protection contexts. An equation grounded in numerical principles was developed to empirically derive the transient behaviour of the seepage line, significantly reducing the computational effort compared with numerical methods. This equation can be subjected to a probabilistically supported assessment of homogeneous levees, contributing to an improved understanding of transient geohydraulic conditions.     «

When analysing the slope stability of levees, the soil mechanical parameters of the saturated and unsaturated cross-sectional areas are the key influencing factors. Thus, prediction of the seepage line is necessary. In practice, steady-state boundary conditions are typically assumed, where the seepage line reaches the maximum elevation within the levee. This scenario leads to conservative, potentially oversimplified safety assessments, reflecting the awareness that the actual level of safety is...     »