The propagation of complex flood-induced head wavefronts through a heterogeneous alluvial aquifer and its applicability in groundwater flood risk management

- We studied the head disturbances induced by flood events in a heterogeneous aquifer.
- Correlation has allowed to identify the controlling factors in groundwater inundation.
- Two synthetic models for groundwater inundation have been developed.
- Decision-support tools in groundwater flood risk management are provided.

SummaryThe extraordinary rise of piezometric surface in aquifers may induce an unexpected interaction of groundwater with anthropogenic elements known as groundwater inundation phenomena. This could result in several damage processes, including building foundation destabilization, groundwater infiltration and pollutant remobilization, which are responsible for considerable economic losses worldwide. To improve our knowledge concerning flood-induced head wavefront propagation and groundwater inundation phenomena, the reconstructed kinematics of the head wavefronts obtained from a calibrated groundwater model simulating 12 ordinary flood events have been statistically analyzed. The correlation between kinematic variables of a flood-induced head wavefront, flood event characteristics and aquifer properties was the basis for the study of the aquifer response to river flood events along four different trajectories, i.e. the identification of river level rise rate, absolute-relative height of the maximum rise stage, hydraulic parameter variability, river-aquifer exchange rates, pre-event state of the aquifer and distance to the aquifer boundary as the key-influencing factors in groundwater inundation. Finally, model and scenario results were used to develop two synthetic models for groundwater inundation as novel decision-support tools for assessing both ordinary and extraordinary flood events in groundwater flood risk management and in urban development planning. These synthetic models gives the technical criteria to predict extraordinary rise of piezometric surface and therefore allows increasing the confidence of stakeholders in the risk assessment and improving the subsurface infrastructure design to mitigate damage processes derived from groundwater interaction.