GroMoPo Metadata for Paris Basin Newsam model

In the framework of evaluating the safety of a radioactive waste disposal in deep argillaceous formations and its assessment by the implementer, IRSN and MINES ParisTech built a hydrogeological model of the Paris Basin aquifer system with the aim of identifying radionuclide pathways, estimating transfer times associated with those pathways and locating potential outlets. Such modelling of fluid and mass transport through a sedimentary basin is a recurrent applied geology study. However, recent research shows that in a deep and saline environment, density effects induced by both temperature (to a small extent) and particularly salt concentration can play a major role in the predicted groundwater flow pathways. The present study highlights the relevance of building a hydrogeological model from the measured hydrogeological and hydrogeochemical parameters by combining the calibration of the piezometric levels and the salinity values simultaneously. The application of this strategy to the Paris Basin shows that the Keuper halite formation (Triassic), located in the eastern part of the basin, can be considered as the unique salt source, provided that the density effects are taken into account in the flow and transport modelling. The calibration requires, in particular, to also take into account some of the basin's major tectonic faults, which allow vertical hydraulic connections between aquifers and thus allow salt water fluxes toward the shallower formations. The results presented in this paper show that when considering \"thermohaline\" effects, the model effectively reproduces the observed hydraulic heads and salinity values throughout the entire Paris Basin, whilst at the same time outlining the role of faults and of the geometry of geological formations on salt transport. (C) 2012 Elsevier B.V. All rights reserved.在深层黏土质地层放射性废物处置安全性评估及其实施方开展的相关安全评估框架下，IRSN与MINES ParisTech构建了巴黎盆地含水层系统水文地质模型（hydrogeological model），旨在识别放射性核素（radionuclide）迁移路径、估算各路径对应的运移时长并定位潜在释出点。 此类针对沉积盆地的流体与物质运移模拟，是应用地质学领域的常规研究课题。然而近期研究显示，在深层高盐环境中，由温度（影响程度较小）尤其是盐浓度诱发的密度效应，会对预测的地下水流路径起到关键调控作用。 本研究阐明，通过同步校准测压水位与盐度值，基于实测水文地质与水文地球化学参数构建水文地质模型具备必要性与合理性。将该策略应用于巴黎盆地的研究结果表明，若在流场与运移模拟中纳入密度效应，则位于盆地东部的三叠纪克珀尔盐岩地层（Keuper halite formation）可被认定为唯一盐源。 该校准流程尤其需要考虑盆地内部分大型构造断层——这些断层可实现含水层间的垂向水力连通性，进而使咸水得以向浅层地层运移。 本文呈现的研究结果显示，当考虑热盐效应（thermohaline effects）时，该模型可有效复现整个巴黎盆地实测的水头与盐度数据，同时阐明了断层与地质体几何形态对盐运移过程的调控作用。©2012 Elsevier B.V. 保留所有权利。