This article presents the seismic displacement analysis of ash dyke slope located at Siripalli, Jharsuguda region in India considering the influence of one-dimensional steady state surface flux of water under seismic excitation. The reported seismic slope displacement and stability values, considering the variable saturation of the geo-structure, serve as a more reliable indicator of the seismic performance of the ash dyke slope under an earthquake condition. The liquefaction susceptibility of the subsoil as well as the ash dyke was carried out and has been presented. For all the analysis, two-dimensional non-linear finite element analysis technique using PLAXIS2D has been adopted. Sinusoidal harmonic excitation of varying frequencies is used as input motion for a comprehensive dynamic analysis. To cater for different intensity of rainfalls, five different magnitudes of steady surface flux are considered. The analysis reveals that during an earthquake, the magnitude of seismic crest displacement is influenced by the presence of the vadose zone. Additionally, under infiltration conditions, the stability of the pond dyke slope further decreases, and this reduction is influenced by the soil water characteristic curve parameter of the dyke slope material. Thus, rational seismic design of dyke slope necessitates consideration of unsaturation parameters.