**4. Conclusions**

In all the study periods (1992–1997, 2004–2009, and 2010–2015) a gradual increase in high and medium vulnerability values (0.5–2%) was observed, a fact due to changing parameters such as the hydraulic load above sea level, the existing salinity condition, and the aquifer thickness, which change with time. For the GALDIT index, the standard/typical weights and the weights of the AHP Median and AHP Average statistical indicators showed

in all study periods a similar overall rate of high vulnerability with a difference of 0.5–1%. Additionally, there are marginal differences in the correlation coefficients between the GALDIT indices and the observed data, with the GALDIT index generated using standard weights displaying the highest connection throughout all research periods. As a result, when compared to the other indices, the standard weights of the GALDIT index slightly better represent the vulnerability assessment both spatially and statistically. The GALDIT method assigns the greatest weights to the parameter of distance from the coast (D) and to the parameter of hydraulic load above the sea (L).

**Author Contributions:** Conceptualization, methodology, supervision, writing—review and editing, A.L. (Athanasios Loukas); methodology, software, data curation, writing—original draft preparation, writing—review and editing, S.L.; writing—review and editing, A.L. (Aikaterini Lyra). All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This research was carried out in the framework of the master's thesis of S. Lepuri, Laboratory of Hydraulic Works and Environmental Management, School of Rural and Surveying Engineering, Aristotle University of Thessaloniki.

**Conflicts of Interest:** The authors declare no conflict of interest.
