This study analyses how indicators of water quality (thirteen physico-chemical variables) and drivers of change (i.e., monthly aggregated air temperature and streamflow, population density, and percentage of agricultural land use) coevolve in three large European river basins (i.e., Adige, Ebro, Sava) with different climatic, soil and water use conditions. Spearman rank correlation, Principal Component Analysis, and Mann-Kendall trend tests were applied to long-term time series of water quality data during the period 1990–2015 in order to investigate the relationships between water quality parameters and the main factors controlling them. Results show that air temperature, considered as a proxy of climatic change, has a significant impact, in particular in the Adige and Ebro: positive trends of water temperature and negative of dissolved oxygen are correlated with upward trends of air temperatures. The aquatic ecosystems of these rivers are, therefore, experiencing a reduction in oxygen, which may exacerbate in the future given the projected further increase in temperature. Furthermore, monthly streamflow has been shown to reduce in the Ebro, thereby reducing the beneficial effect of dilution, which appears evident from the observed upward patterns of chloride concentrations and electrical conductivity. Upward trends of chloride and biological oxygen demand in the Adige and Sava, and of phosphate in the Adige appears to be related to increasing human population density, whereas phosphates in the Sava and biological oxygen demand in the Ebro are highly correlated with agricultural land use, considered as a proxy of the impact of agricultural practises.The present study shows the complex relationships between drivers and observed changes in water quality parameters. Such analysis can represent, complementary to a deep knowledge of the investigated systems, a reliable tool for decision makers in river basin planning by providing an overview of the potential impacts on the aquatic ecosystem of the three basins.

中文翻译：

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驱动程序检测欧洲三个大型流域的水质趋势

这项研究分析了三个欧洲大河流域（即阿迪杰）的水质指标（十三个理化变量）和变化驱动因素（即每月总气温和水流量，人口密度和农业用地百分比）如何演变。 ，埃布罗（Ebro），萨瓦（Sava）的气候，土壤和水的使用条件不同。为了研究水质参数与控制它们的主要因素之间的关系，将Spearman等级相关性，主成分分析和Mann-Kendall趋势检验应用于1990-2015年期间的水质数据的长期时间序列。结果表明，气温被认为是气候变化的代表，尤其在阿迪杰和埃布罗（Ebro）方面具有重大影响：水温的正趋势和溶解氧的负趋势与气温的上升趋势相关。因此，这些河流的水生生态系统正经历着氧气的减少，鉴于预计温度会进一步升高，这种情况将来可能会加剧。此外，Ebro的每月流量已显示减少，从而降低了稀释的有益效果，这从观察到的氯离子浓度和电导率的上升模式中可以明显看出。阿迪杰和萨瓦的氯化物和生物需氧量以及阿迪杰的磷酸盐的上升趋势似乎与人口密度的增加有关，而萨瓦的磷酸盐和埃布罗的生物需氧量与农业土地利用高度相关，本研究显示了驱动因素与观测到的水质参数变化之间的复杂关系。通过提供对三个流域水生生态系统的潜在影响的概述，这种分析可以补充对所研究系统的深入了解，为流域规划中的决策者提供一种可靠的工具。