Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-447
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
27 Jul 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Groundwater withdrawal in randomly heterogeneous coastal aquifers
Martina Siena1 and Monica Riva1,2 1Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, Italy
2Department of Hydrology and Atmospheric Sciences, Universit y of Arizona, Tucson, AZ 85721, USA
Abstract. We analyze the combined effects of aquifer heterogeneity and pumping operations on seawater intrusion (SWI) in coastal aquifers, a phenomenon which is threatening Mediterranean and worldwide regions. We conceptualize the aquifer as a three-dimensional randomly heterogeneous porous medium, where the spatial distribution of permeability is uncertain. The geological setting of our study is patterned after the coastal aquifer of the Argentona river basin, in the Maresme region of Catalonia (Spain). Numerical simulations of transient, three-dimensional, variable-density flow and solute transport are performed within a stochastic Monte Carlo framework. We consider a variety of groundwater withdrawal schemes, designed by varying the screen location along the vertical direction and the distance of the wellbore from the coastline and from the freshwater-saltwater mixing zone, in order to assess the impact of the pumping scenario on the contamination of the freshwater pumping well for a prescribed production rate. SWI is analyzed by examining isoconcentration curves and global dimensionless quantities characterizing (i) inland penetration of the saltwater wedge and (ii) width of the mixing zone. Our results indicate that heterogeneity affects the (three-dimensional) seawater wedge either in the presence or in the absence of pumping, by reducing toe penetration and enlarging the width of the mixing zone. Simultaneous extraction of fresh and saltwater from two screens along the same wellbore located within the transition zone is effective in limiting SWI during groundwater resources exploitation.

Citation: Siena, M. and Riva, M.: Groundwater withdrawal in randomly heterogeneous coastal aquifers, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-447, in review, 2017.
Martina Siena and Monica Riva
Martina Siena and Monica Riva
Martina Siena and Monica Riva

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Short summary
The development of sustainable strategies for groundwater resources exploitation in coastal regions is subordinated to the characterization of seawater intrusion (SWI) phenomena. We develop a numerical model tailored to a real coastal aquifer to investigate quantitatively the joint effects of hydraulic properties heterogeneity and pumping configuration on saltwater inland penetration and saltwater-freshwater mixing. Our results allowed identifying efficient scenarios for the reduction of SWI.
The development of sustainable strategies for groundwater resources exploitation in coastal...
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