INTRAVAL Phase 2, test case. Saline Groundwater Movement in an Erosional Channel Crossing a Salt Dome
Weert FHA van Hassanizadeh SM
Weert FHA van
Hassanizadeh SM
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Open Access
Type
Report
Language
en
Date of publication
1992-08-31
Year of publication
Research Projects
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Journal Issue
Title
INTRAVAL Phase 2, test case. Saline Groundwater
Movement in an Erosional Channel Crossing a Salt Dome
Translated Title
INTRAVAL fase 2, test case. Zout grondwater
stroming door een "rinne" boven een zoutkoepel
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Abstract
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The Gorleben salt dome is overlain by Tertiary and Quaternary sediments, which form a complex hydrogeological system of aquifers and aquitards. In general one can recognize a lower and an upper aquifer both consisting of sand and gravel, and an intermediate clay complex isolating the two aquifers. In this study, the "Weisses Moor" pumping test data are used to obtain information about the hydraulic properties of the Gorleben system. The interpretation of the Weisses Moor pumping test will be carried out in steps of increasing difficulty. This report contains the results of the first step of modelling. It is assumed that the variations in the salt concentration can be neglected and that the porous medium is homogeneous and isotropic. Under such circumstances, the drawdowns observed in the observation wells due to a pumping test can be described by the Theis solution. The AQ-AT code, developed at RIVM, is used to minimize the sum of squared differences between the observed and theoretical drawdown to obtain optimal values of storativity and transmissivity. It appears that there are significant differences between the optimal values calculated for various observation wells. Therefore, the assumptions of homogeneity, isotropy and/or constant salt concentration do not apply. These assumptions will be relaxed in the following modelling steps in order to obtain more satisfactory results.
The Gorleben salt dome is overlain by Tertiary and Quaternary sediments, which form a complex hydrogeological system of aquifers and aquitards. In general one can recognize a lower and an upper aquifer both consisting of sand and gravel, and an intermediate clay complex isolating the two aquifers. In this study, the "Weisses Moor" pumping test data are used to obtain information about the hydraulic properties of the Gorleben system. The interpretation of the Weisses Moor pumping test will be carried out in steps of increasing difficulty. This report contains the results of the first step of modelling. It is assumed that the variations in the salt concentration can be neglected and that the porous medium is homogeneous and isotropic. Under such circumstances, the drawdowns observed in the observation wells due to a pumping test can be described by the Theis solution. The AQ-AT code, developed at RIVM, is used to minimize the sum of squared differences between the observed and theoretical drawdown to obtain optimal values of storativity and transmissivity. It appears that there are significant differences between the optimal values calculated for various observation wells. Therefore, the assumptions of homogeneity, isotropy and/or constant salt concentration do not apply. These assumptions will be relaxed in the following modelling steps in order to obtain more satisfactory results.
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