Climate Control of Multidecadal Variability in River Discharge and Precipitation in Western Europe

• Published in: Water
• Main Authors: Isabel Jalón-Rojas, Bruno Castelle
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: multidecadal variability; river discharge; precipitation; climate indices; NAO; WEPA; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; Winter River; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.3390/w13030257; https://doaj.org/article/8f501cadada8491393dcc2f4e90870f9

The influence of large-scale climate variability on winter river discharge and precipitation across western Europe is investigated. We analyze 60 years of monthly precipitation and river flow data from 18 major western-European rivers and its relationship with dominant teleconnection patterns and climate indices in this region. Results show that winter river flow is characterized by large interannual variability, best correlates with (a) the North Atlantic Oscillation (NAO) at the far-northern (R up to 0.56) and southern latitudes (R up to −0.72), and (b) the West Europe Pressure Anomaly (WEPA) at the middle and northern latitudes, from 42° N to 55° N (R up to 0.83). These indices also explain the interannual variability in autumn and spring discharge in rivers characterized by secondary floods. Compared to the other leading modes of atmospheric variability, WEPA increases the correlations with winter precipitation up to 0.8 in many regions of western and central Europe. A positive WEPA corresponds to a southward shift and an intensification of the Icelandic-Low/Azores-High dipole, driving enhanced precipitation and river discharge in these regions. The correlations with precipitation are slightly higher than those with river discharge, particularly in France, with clear latitudinal gradient. This trend suggests that water storage variability and other catchment characteristics may also influence the interannual variability of river discharge. Seasonal forecasting of the WEPA and NAO winter indices can become a powerful tool in anticipating hydrological risks in this region.