**5. Conclusions**

In this study, the physically-based hydrological model MIKE SHE and Copernicus Climate Change Service E-OBS gridded meteorological dataset were used to analyze the e ffects of anthropogenic land cover changes to the hydrological cycle components of the regional watershed of Spercheios river in central Greece. Three case studies based on the land cover of the years 1960, 1990, and 2018 were investigated.

The analysis of simulation results showed that phenomena like deforestation reduced mean annual actual evapotranspiration while increasing mean annual river discharge. The increase of irrigated agricultural land and irrigation demand also increased discharge as revealed by the results of the case study based on the latest land cover of 2018. Even though irrigation often reduces overland water resources, the exploitation of underground waters can increase river discharge.

Moreover, the climatic variabilities primarily in precipitation and secondarily in temperature influenced annual actual evapotranspiration and annual river discharge. Nevertheless, the response of various watershed areas on land cover changes was shown to be more significant, hiding the e ffects of climatic variabilities. Land cover changed among the case studies, and thus, locally exceeded the impact of climatic variabilities as indicated by the reduced interannual variabilities of di fferences in annual actual evapotranspiration. The inhomogeneity of land cover as well as the reduction of vegetated areas were highlighted as the main reasons for this e ffect.

Remarkably, an in-depth trend analysis unveiled the e ffect of land cover on increasing the vulnerability on extreme climatic variabilities causing intense hydrometeorological events, either droughts or floods. This means that the resilience of the watershed to extreme weather and climatic phenomena was higher in cases of increased vegetated area, since the response of river discharge in changes of hydrometeorological factors and precipitation was milder in cases of land cover dominated by forested land. This finding highlights the fact that the natural systems under stress mainly due to land cover changes and anthropogenic interventions are likely to have more rapid and acute reactions to climatic variabilities.

Understating the complex interactions among multiple stressors—land degradation and hydrometeorological hazards—can contribute to the development and implementation of successful Integrated Water Resources Management plans. Given the high level of uncertainty of climate change projections and related impacts on water resources, the e ffects of climatic variabilities on freshwater resources cannot be quantified in a deterministic way; decision-making should be rather based on possible future freshwater hazards and risks. Under this scope, the quantitative assessment of land cover e ffects presented in this study can be a basis for adaptation and mitigation to climate change and human interventions.

**Author Contributions:** Conceptualization, A.M., G.V., E.D., A.P., I.P. and P.K.; Formal analysis, A.M. and G.V.; Investigation, A.M., E.D., A.P., I.P. and P.K.; Methodology, A.M., G.V., E.D., A.P., I.P. and P.K.; Resources, A.M.; Supervision, E.D., A.P., I.P. and P.K.; Validation, A.M. and G.V.; Visualization, A.M. and G.V.; Writing—original draft, A.M., G.V., E.D., A.P., I.P. and P.K.; Writing—review & editing, A.M., G.V., E.D., A.P., I.P. and P.K.

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

**Acknowledgments:** We acknowledge the E-OBS dataset from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu).

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