**5. Conclusion**

In many countries, the regulation of hydraulic structures has recently been enhanced and is declined in classes depending on the issues in case of breakage. It stresses the need to know the level of safety of the structures, through in-depth diagnosis and analysis of risks, and to strengthen the surveillance. In France, these regulations now apply to 700 large dams, tens of thousands of small dams, and about 10 000 km of linear dikes.

We have presented in this chapter on going improvements in the global methodology of dike diagnosis in Europe. The stakeholders involved in the management of dikes must continue to integrate these improvements in their practices so that an efficient diagnosis should be drawn over time for a sustainable maintenance of the earthworks and dams.

Nowadays, the ERT method becomes the reference one for dike and dam geophysical investigations. Coupled with accurate 3D topographic data acquired with a LiDAR system, the 3D effects should be better integrated when interpreting the data. Those improvements will be all the more interesting for stakeholders (e.g. multi temporal analysis of long stretch dikes) as repetitive survey will be performed.

Phenomena like leakage or seepage are still difficult to detect and future research works on streaming potential (Bolève et al., 2007) and optic fibres (Khan et al., 2010) methods should supplement the available tools of stakeholders.
