65-year changes of annual streamflow volumes across Europe with a focus on the Mediterranean basin

Abstract

Abstract. Determining the spatio-temporal variability of annual streamflow volume plays a relevant role in hydrology for improving and implementing sustainable and resilient policies and practices of water resource management. This study investigates annual streamflow volume trends in a newly-assembled, consolidated and validated dataset of daily mean river flow records from more than 3,000 stations, which cover near-natural basins in more than 40 countries across Europe. Although the dataset contains streamflow time-series from 1850 to 2015 in some stations, the statistical analyses were carried out by including observations from 1950 to 2015 in order to have a consistent and reliable dataset over the continent. Trends were detected calculating the slope of Theil-Sen's line over the annual anomalies of streamflow volume. The results show annual streamflow volume trends emerged at European scale, with a marked negative tendency in Mediterranean regions (about −1 × 103 m3/(km2 year)) and a generally positive trend in northern ones (about 0.5 × 103 m3/(km2 year)). The annual streamflow volume trend patterns appear in agreement with the continental-scale climate change observations in response to climate change drivers. In the Mediterranean area, the declining of annual streamflow volumes started in 1965 and since early 80' volumes are consistently lower than the average. The spatio-temporal annual streamflow volume patterns observed in this work can help to contextualize short-term trends and regional studies already available in the scientific literature as well as to provide a valid benchmark for further accurate quantitative analysis on annual streamflow volumes.

The Complex and Spatially Diverse Patterns of Hydrological Droughts Across Europe

“…The transitional region, mainly located in France, exhibited less clear trends. These results are in agreement with previous regional assessments, even those which relied on a lower density of stations (e.g., Dalezios et al, 2000;Fleig et al, 2006;Hisdal et al, 2001;Masseroni et al, 2020;Van Lanen et al, 2013;Van Loon & Laaha, 2015).…”

An Assessment of the Recent Evolution of the Streamflow in a Near-Natural System: A Case Study in the Headwaters of the Mero Basin (Galicia, Spain)

“…Additionally, human activities can greatly influence the river systems and make it difficult for trend detection and attribution [6,7]. Against this background, streamflow measures in natural or near-natural rivers become of prime importance in understanding hydrological processes in an area and identifying and attributing emerging trends [8][9][10]. Hydrological predictive modellings also require adequate and suitable local data to represent rainfall-runoff processes accurately.…”

Unravelling Climate and Anthropogenic Forcings on the Evolution of Surface Water Resources in Southern France

“…Many studies have analyzed hydro-climate trends in the Mediterranean Region over recent decades (see the reviews from [8,9]). Especially in Spain and France, a series of studies have reported seasonal and annual decreasing trends for water discharge of coastal rivers which are likely to be linked to recent climatic evolution [10][11][12][13][14]. However, streamflow trends can be attributed to several…”