Akademik Veri Yönetim Sistemi
Sustain Istanbul 2024 - Towards Sustainable Groundwater Use under Changing Climate, İstanbul, Türkiye, 9 - 11 Ekim 2024, ss.33, (Özet Bildiri)
This
study presents the outcomes of modeling studies conducted as part of the PRIMA
RESERVOIR project, which aims to develop an innovative approach to address land
subsidence resulting from excessive groundwater extraction in water-stressed
Mediterranean watersheds. By integrating earth-observation-derived land
subsidence rates with an iterative implementation of numerical groundwater flow
and geomechanical modeling, we developed an approach to improve the estimation
of hydrogeological parameters.
It
is known that the response of an aquifer to groundwater pumping is
predominantly influenced by saturated hydraulic conductivity (K) and the
oedometric bulk compressibility (Cm). While K determines the
variation in groundwater pressure, Cm influences both the
deformation of the pore volume and the rate of pressure variation over time. To
optimize the characterization of aquifer properties, K and specific storage, hydraulic
head measurements from monitoring wells, and displacement measurements from Interferometric
Synthetic Aperture Radar (InSAR) data were utilized. This was achieved through
a novel procedure using a 3D groundwater flow simulator (MODFLOW) and a 3D
geomechanical simulator (GEPS3D) in an iterative coupled approach, with spatial
variations of specific storage and K described as stationary Gaussian random
fields.
The
Alaşehir-Sarıgöl alluvial aquifer case in the Gediz River basin (Turkiye),
where groundwater withdrawal for irrigation has led to significant land
subsidence of up to 10 cm/yr, serves as a demonstration of the presented
approach. Simulated hydraulic heads from the flow model were input into the
geomechanical model, allowing the calculation of displacement time series for
the subsiding areas, which were then compared to InSAR data. The fit between
simulated and observed subsidence trends was improved by iteratively adjusting
the specific storage parameter value, consequently leading to an improvement in
model performance. These models are expected to be more reliable for water
management decision-making. The iterative procedure highlighted considerable
heterogeneity in the parameter distribution, underscoring the importance of
satellite-based land subsidence measurements for constraining parameters of
groundwater flow models.
Ultimately,
the study underscores the importance of accurately characterizing aquifer
properties to enhance groundwater management. By improving the estimation of
the storage coefficient and employing it in groundwater storage calculations,
more accurate estimations of groundwater availability are expected.
Acknowledgment: This
study is funded by the PRIMA program under grant agreement No: 1924, project
RESERVOIR. The PRIMA program is supported by the European Union.