The paper provides interesting results concerning the effects of linear versus non linear flow on transport. However, it requires some improvements and more discussion in the assumptions you made. Therefore, the manuscript needs major revision. Please do the revision you suggested in the responses to the reviewers and answer the following questions/comments:
1. The observed high hydraulic heads has to be better explained (L359-L366). It cannot be due to the zone of poor connection only.
2. The flow model is calibrated in steady state on data collected in Feb. 2012. Are these data representative of steady state?
3. There is salt water intrusion at the coast boundary and it seems you neglected it in the modelling. Why?
4. The transport seems to be simulated in 2D. Are you sure that the concentration at the source is homogeneous over the all depth of the aquifer to allow this approximation? Are the measured concentrations representative of the average concentration over the depth?
5. The subtitle L356 is misleading. How did you detect the sources?
6. The most innovative part of the work is the comparison between linear and non-linear flow. (Fig. 13). Please provide more information and highlight the differences between Cherubini et al (2014) work.

Please answer properly questions 1 and 2.
Q1: The local high value of the piezometric head cannot be due to heterogeneity only. There should be some additional recharge.
Q2: I am asking you if the data are representative of steady state conditions. Of course, they will show a trend but they may differ from steady state conditions.

Thank you for your contribution.