GroMoPo Metadata for Chaudire-Appalaches regional model

As part of the Quebec PACES III provincial groundwater resources assessment programme (Programme d'acquisition des connaissances en eaux souterraines), a regional-scale two-dimensional numerical groundwater model was developed in the Chaudiere-Appalaches region, Quebec, Canada. The model considers groundwater flow, transport of groundwater age and the influence of a fault on the flow system and its implications for groundwater quality. By including deep and shallow flow systems, the study helps fill a knowledge gap with respect to intermediate flow systems and the role they would play during potential energy resource development including shale gas exploitation from the Utica Shale. Physical and chemical hydrogeological data, including an analysis of C-14 in dissolved inorganic carbon in sampled groundwater, supported a regional conceptual flow model forming the basis for numerical simulations. The numerical model is first calibrated to regional piezometry through a semi-automated workflow using the inverse model PEST. Although some evidence for deeper regional flow exists, the area appears to be dominated by local flow systems on maximum length scales of about 5 km, with significant flow through the top 40 to 60 m of the fractured sedimentary rock aquifer. This regional-scale flow model is also supported by the local hydrogeochemical signatures. Simulated mean groundwater ages show young shallow water of <100 years with rapid increases in age with depth suggesting diffusion-controlled age evolution. Groundwater age is likely being perturbed in the vicinity of the Jacques Cartier River fault, which can act as both a barrier and a preferential pathway, provided permeability contrasts with the surrounding rock are at least two orders of magnitude.

作为魁北克省地下水资源评估计划（Programme d'acquisition des connaissances en eaux souterraines）的一部分，魁北克省的 Chaudiere-Appalaches 地区建立了一个区域尺度的二维数值地下水模型。该模型考虑了地下水流动、地下水年龄的传输以及断层对流动系统及其对地下水质量影响的作用。通过纳入深层和浅层流动系统，本研究有助于填补关于中等流动系统及其在潜在能源资源开发中，包括尤蒂卡页岩气开采中所扮演角色的知识空白。物理和化学水文地质数据，包括对样本地下水中溶解无机碳中C-14的分析，支持了形成数值模拟基础的区域性概念流动模型。该数值模型首先通过使用逆模型PEST的半自动化工作流程对区域水位进行校准。尽管存在较深区域流动的证据，但该区域似乎在最大长度尺度上主要由约5公里的局部流动系统所主导，且在裂隙沉积岩含水层顶部40至60米范围内存在显著的水流。该区域尺度的流动模型也得到了局部水文地球化学特征的支持。模拟的平均地下水年龄显示出<100年的年轻浅层水，随着深度的增加年龄迅速上升，表明扩散控制的年龄演化。地下水年龄在Jacques Cartier河断层附近可能受到干扰，该断层既可以作为障碍，也可以作为优先通道，前提是与周围岩石的渗透率对比至少有两个数量级。