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Conclusions
Water resources especially the groundwater are among the natural
resources being subjected to ignorance by human communities around the
world. The impacts of the climate change mostly in terms of reduced
precipitation and increased temperatures accompanied by misuse and
mismanagement of these resources contribute to great losses and in some
cases resulted in irreversible impacts on surface and subsurface waters.
The problem is especially more common in arid and semi-arid regions
where there is a huge pressure on groundwater resources. The
environmental impacts of the overuse of groundwater aquifers include the
socio-economic losses in the form of increased exploitation costs for
water provision as well as the costs for making up for the environmental
damages and the challenges of migration etc. On the other hand, the
losses imposed on the environment by the groundwater degradation vary
from land subsidence, water quality degradation to drying up of the
wells nearby.
Turkey is going to be one of the problematic countries in regard of
water issues especially in near future. Some of the regions of the
country especially the Aegean and Central Anatolian regions have been
challenging with the groundwater depletion and its consequences during
recent years. Taking into account the limitations of the traditional
approaches for monitoring water resources particularly in large scales,
the use of remote sensing technology has become popular and common among
the scholars and decision makers as well in recent years especially with
the emergence of GRACE satellites and the development of data modelling
and assimilation systems. Taking the benefits of remotely sensed data,
the variations of terrestrial water and groundwater storage over Turkey
were analyzed in this study. The results suggested that the total trend
of monthly TWSA and GWSA over Turkey is descending with a total decrease
of 11 and 6 cm from 2003 to 2016, respectively. The interactions of the
GWSA with climatic variables of precipitation and temperature were also
studied. The results indicate that there is a good agreement between
GWSA and climatic variables with 2-month lag. The best correlation was
found between climatology values of precipitation and temperatures and
GWSA. The monthly statistics revealed that the impact of increased
temperatures on the variations of groundwater storage over Turkey is
much more evident compared to precipitation, which indicates that the
evapotranspiration resulting from warm weather condition in the country
controls the variations of GWS. However, the regression results show
that the variations of GWS over Turkey can be modelled with high
accuracy using the climatic variables. Findings of this study emphasized
the overall feasibility of satellite and modelled datasets to study the
large-scale fluctuations of hydro-climatic variables in at country or
regional extends.