Impact of animal burrows on earthen levee body vulnerability to seepage

A novel procedure for estimation of the vulnerability to seepage inducing piping processes in earthen levees affected by animal burrows is presented. The proposed methodology combines an available procedure of seepage vulnerability assessment for undamaged levees with the result of a finite element analysis software, which is used for identifying the seepage path and hydraulics head profile of both damaged and undamaged levees. The main steps of the procedure for estimating the impact of burrows in increasing the vulnerability of levees are presented. Twenty-one levees along the Tanaro River (north-western Italy) are used as a case study, and the results show that the critical conditions for the onset of inner erosion are achieved for shorter flood durations in damaged levees. If burrows occur, the probability of inner erosion (seepage probability) increases resulting in a potential increase of forming longer tunnels. This approach is a first attempt to quantify the seepage probability of extended levee systems affected by burrows and is applied for simplified geometrical and two-dimensional representation of the cavities. This procedure can be applied by the hydraulic authorities to set the priorities in levees maintenance. Future research would focus on the analysis of more realistic burrows conditions.