GroMoPo Metadata for NE Belgium Neogene aquifer model

Direct push (DP) technologies are typically used for cost-effective geotechnical characterization of unconsolidated soils and sediments. In more recent developments, DP technologies have been used for efficient hydraulic conductivity (K) characterization along vertical profiles with sampling resolutions of up to a few centimetres. Until date, however, only a limited number of studies document high-resolution in situ DP data for three-dimensional conceptual hydrogeological model development and groundwater flow model parameterization. This study demonstrates how DP technologies improve building of a conceptual hydrogeological model. We further evaluate the degree to which the DP-derived hydrogeological parameter K, measured across different spatial scales, improves performance of a regional groundwater flow model. The study area covers an area of similar to 60 km(2) with two overlying, mainly unconsolidated sand aquifers separated by a 5-7 m thick highly heterogeneous clay layer (in northeastern Belgium). The hydrostratigraphy was obtained from an analysis of cored boreholes and about 265 cone penetration tests (CPTs). The hydrogeological parameter K was derived from a combined analysis of core and CPT data and also from hydraulic direct push tests. A total of 50 three-dimensional realizations of K were generated using a non-stationary multivariate geostatistical approach. To preserve the measured K values in the stochastic realizations, the groundwater model K realizations were conditioned on the borehole and direct push data. Optimization was performed to select the best performing model parameterization out of the 50 realizations. This model outperformed a previously developed reference model with homogeneous K fields for all hydrogeological layers. Comparison of particle tracking simulations, based either on the optimal heterogeneous or reference homogeneous groundwater model flow fields, demonstrate the impact DP-derived subsurface heterogeneity in K can have on groundwater flow and solute transport. We demonstrated that DP technologies, especially when calibrated with site-specific data, provide high-resolution 3D subsurface data for building more reliable conceptual models and increasing groundwater flow model performance. (C) Springer-Verlag Berlin Heidelberg 2014

直推式钻探（Direct Push, DP）技术通常被用于实现松散土层与沉积物的低成本岩土工程特性表征。近年来，该技术已被用于沿垂直剖面开展高效的水力传导系数（hydraulic conductivity, K）表征工作，其采样分辨率最高可达数厘米级别。然而截至目前，仅有少量研究记录了用于构建三维概念水文地质模型与开展地下水流模型参数化所需的高分辨率原位DP数据。
本研究阐述了直推式钻探技术如何助力概念水文地质模型的构建。我们进一步评估了通过不同空间尺度实测得到的、由DP技术获取的水文地质参数K，对区域地下水流模型性能的提升程度。
本次研究的研究区面积约60 km²，覆盖比利时东北部区域，其地层由两层上覆的、以松散砂岩为主的含水层组成，两层含水层之间被一层厚度5~7 m的高度非均质黏土层分隔。水文地层学数据取自岩芯钻孔与约265次圆锥静力触探试验（cone penetration tests, CPTs）的分析结果。
水文地质参数K的获取途径包括岩芯与CPT数据的联合分析，以及水力直推式钻探测试。研究团队采用非平稳多元地质统计方法，生成了共计50组K的三维随机实现。为了在随机实现中保留实测K值，地下水流模型的K随机实现以钻孔数据与DP数据作为条件约束。随后开展了优化工作，从50组随机实现中筛选出性能最优的模型参数化方案。相较于此前针对所有水文地质层采用均质K场构建的参考模型，本模型的表现更为优异。
基于最优非均质地下水流场与参考均质地下水流场的粒子追踪模拟对比结果表明，由DP技术获取的地下非均质K分布，会对地下水流与溶质运移过程产生显著影响。本研究证实，直推式钻探技术——尤其是结合场地专属数据进行校准后——能够提供高分辨率的三维地下数据，助力构建更可靠的概念水文地质模型，并提升地下水流模型的整体性能。
(C) Springer-Verlag Berlin Heidelberg 2014