GroMoPo Metadata for La Rochefoucauld Aquifer HPP-GMS model

Ground water flow modeling in a karst aquifer presents many difficulties. In particular, the hydrodynamic properties and the now behavior can vary over time. History matching of transient-state conditions is required to test the accuracy of the model under varying hydrodynamic conditions. The objective of this study was to illustrate how transient-state conditions can be used to history match a ground water flow model of a large aquifer, the La Rochefoucauld karst (Charente, France). The model used a porous medium equivalent and was based on a steady-state calibration of hydraulic conductivities. The history match consisted of studying the simulated heads and spring flow rates to test the capacity of the model to reproduce different aspects of the aquifer behavior, The simulated heads and flow rates were analyzed as new data using correlation and spectral analyses to compare the temporal structures of the measured and simulated time series. The analyses provided information on the storage capacity of the aquifer, the input-output delays, the degree of correlation between input and output, and the length of the impulse response of the aquifer, These data were used to study the impact of the hypotheses underlying the model (hydraulic conductivities, storage coefficient, representation of rivers, use of a porous medium equivalent). The results show that the model adequately simulates the overall behavior of the studied aquifer, The model can be used under variable hydrodynamic conditions to simulate ground water flow on a regional scale. This case study illustrates how a complete history match of a simplified representation of reality can lead to an adequate mathematical tool.喀斯特含水层的地下水流动模拟面临诸多难题，其水动力特性与流动行为会随时间发生变化。为在变化的水动力条件下验证模型精度，需开展瞬态条件（transient-state conditions）下的历史拟合（history matching）工作。本研究旨在阐明，如何利用瞬态条件对大型含水层——法国夏朗德省拉罗什富科（La Rochefoucauld）喀斯特含水层的地下水流动模型开展历史拟合。该模型采用等效多孔介质（porous medium equivalent）表征方式，基于水力传导率（hydraulic conductivities）的稳态校准构建。本次历史拟合通过分析模拟水头与泉水流量，验证模型复现含水层多维度行为的能力；同时将模拟水头与流量作为新数据集，借助相关分析（correlation analyses）与谱分析（spectral analyses），对比实测与模拟时间序列（time series）的时域结构特征。上述分析获取了含水层储水能力、输入输出延迟、输入输出相关程度以及含水层脉冲响应（impulse response）时长等信息；基于这些数据，本研究探讨了模型隐含的各项假设（包括水力传导率、储水系数（storage coefficient）、河流表征方式以及等效多孔介质的使用）对模拟结果的影响。结果表明，该模型能够较好地复现研究含水层的整体行为，可在变化的水动力条件下用于区域尺度的地下水流动模拟。本案例研究表明，针对现实的简化表征开展完整的历史拟合，可得到性能可靠的数学模拟工具。