Abstract Hydrogeochemical studies can provide insights to pursue a flexible and responsive groundwater resources management.Origin of water, mixing and reactive processes are three key parameters that allow to understand hydrological systems and resulting groundwater quality.However, those parameters may evolve strongly and quickly over time and space, especially for hydrological system impacted by pumping activities and seasonal variations.Within this framework, the current study aims to pursue a survey of the hydrological parameters in a small dynamic alluvial aquifer fed by 3 contrasted end-members and used for water supply.The variations of the end-members and the alluvial groundwaters quality (Ca2+, Mg2+, K+, Na+, Cl−, CO32−, NO3−, δ2H and δ18O) will be used as a record of those parameters. 26 sampling campaigns were carried out fortnightly from October 2017 to October 2018 and data processed with two distinct mixing models: GLUE-EMMA model, which define likelihood of each mixing component, and PHREEQC inverse modeling, which account for the reactive processes that occur as water chemistry evolves. For each studied groundwater, appropriate time variant end members signatures as well as analytical uncertainties were accounted and models constrained to fit within 5.0% for the major ions and 0.5‰ for water stable isotopes.With suitable models for all alluvial groundwater samples, both GLUE-EMMA and PHREEQC highlight the mixing process between two end-members as the main parameter of the alluvial groundwater quality. Nonetheless, Mg2+ and K+ reactive fluxes are needed to fit with the required constraints.Hence, the alluvial groundwater quality variations are either associated with the typical seasonal variations of the end-member signature and the change of the mixing processes.For both models, mixing process exhibits slow and small as well as strong and sudden changes. The first can be related with the relative capacity of the end members to feed the aquifer according to their individual high and low water periods. The second to the effects of alternative pumping regime between sampling campaign.The capacity of both models to evaluate and monitor main hydrological processes, over time and space, confirms the interest to combine them as a flexible multi process investigation suited for dynamic hydrological system.

中文翻译：

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使用混合模型解释狭窄的波动冲积含水层中地下水质量的时间和空间变化

从 2017 年 10 月到 2018 年 10 月，每两周进行 26 次采样活动，并使用两种不同的混合模型处理数据：GLUE-EMMA 模型，它定义了每个混合成分的可能性，以及 PHREEQC 逆模型，它解释了作为水发生的反应过程化学在发展。对于每个研究的地下水，适当的时变端元特征以及分析不确定性都被考虑在内，模型被限制在主要离子的 5.0% 和水稳定同位素的 0.5‰以内。对于所有冲积地下水样本，GLUE- EMMA 和 PHREEQC 强调两个端元之间的混合过程是冲积地下水质量的主要参数。尽管如此，需要 Mg2+ 和 K+ 反应通量来满足所需的约束。因此，冲积地下水水质变化要么与端元特征的典型季节变化有关，要么与混合过程的变化有关。对于两种模型，混合过程都表现出缓慢而小的变化以及强烈而突然的变化。第一个可能与端部成员根据其各自的高水和低水时期向含水层供水的相对能力有关。第二个是采样活动之间替代抽水制度的影响。这两种模型在时间和空间上评估和监测主要水文过程的能力证实了将它们结合为适合动态水文系统的灵活多过程调查的兴趣。