ABSTRACT Diaz-Sanchez, R., Lopez-Gutierrez, J.S., Lechuga, A., Negro, V., 2013. Runup variability due to time dependency and stochasticity in beach profiles. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings of the 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 001-006, ISSN 0749-0208. Equations for extreme runup worked out from several experimental studies are compared. Infragraviatory oscillations dominate the swash in a dissipative state but not in intermediate reflective states. Therefore two kinds of equation depending on either significant wave height, H0, or the Iribarren number, ξ0, should be used. Through a sand bed physical model with a uniform sand bed slope, equations are proposed for both beach states, and results are compared with precedent field and physical model experiments. Once the equations are chosen, the time-longshore variability in a medium long term time scale of the foreshore slope is evaluated in two extre...