The application of a combined reactive transport - density dependent flow model to a real gypsum coastal aquifer (Lesina Marina, Southern Italy) is presented, with the aim of evaluating the potential of gypsum dissolution on sinkholes development. The area has been in fact highly susceptible to hazardous and rapid sinkhole formation since 1927, when a canal was excavated in an evaporite formation, strongly modifying groundwater flow patterns. To achieve this aim, firstly a conceptual model is defined, then a density- dependent, tide-influenced, flow model is set up and solved by means of the numerical code SEAWAT. Finally, the resulting transient flow field is used by the reactive multicomponent transport model PHT3D to estimate gypsum dissolution rate. The multi-disciplinary approach indicates that sinkhole formation in the Lesina Marina area, during the last 90 years, is scarcely connected to recent gypsum dissolution; rather, it is related to the erosion of paleo-cavities filling material (suffosion), caused by the new hydrodynamic conditions induced by the excavation of the canal within the evaporite formation.

MODELING OF GYPSUM DISSOLUTION DRIVEN BY VARIABLE DENSITY FLOW IN THE COASTAL KARST AQUIFER OF LESINA MARINA (SOUTHERN ITALY)

FIDELIBUS, Maria Dolores;
2014

Abstract

The application of a combined reactive transport - density dependent flow model to a real gypsum coastal aquifer (Lesina Marina, Southern Italy) is presented, with the aim of evaluating the potential of gypsum dissolution on sinkholes development. The area has been in fact highly susceptible to hazardous and rapid sinkhole formation since 1927, when a canal was excavated in an evaporite formation, strongly modifying groundwater flow patterns. To achieve this aim, firstly a conceptual model is defined, then a density- dependent, tide-influenced, flow model is set up and solved by means of the numerical code SEAWAT. Finally, the resulting transient flow field is used by the reactive multicomponent transport model PHT3D to estimate gypsum dissolution rate. The multi-disciplinary approach indicates that sinkhole formation in the Lesina Marina area, during the last 90 years, is scarcely connected to recent gypsum dissolution; rather, it is related to the erosion of paleo-cavities filling material (suffosion), caused by the new hydrodynamic conditions induced by the excavation of the canal within the evaporite formation.
23rd Salt Water Intrusion Meeting
978-3-00-046061-6
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11589/20002
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