Annual variation characteristics of Eurasian hydrologic elements and their linkage with climate and environment changes during 1951–2015

Abstract. In this paper, the variations of the lowest monthly discharge (LD), mean monthly discharge (MD), and highest monthly discharge value (HD) during 1951–2015, as well as spring snowmelt water and winter river ice change, in eleven major rivers, distributed respectively in the high-latitudes (55° N–70° N), middle latitudes (40° N–55° N), and lower latitudes (30° N–40° N) of Eurasia, were analysed. Energy and water budgets in different watersheds were compared to detect the reasons for Eurasian hydrological changes. We found that the annual LD in most Eurasian rivers was increasing since the 1950s, with rates of (5 %–8 %) per decade. But the increase rate slowed down after the late 1990s in the middle latitudes of Eurasia. Both the MD and HD in the lower latitudes of Eurasia had increasing trends during 1951–2015, while they had little changes in the high and middle latitudes. The river ice thickness and volume have been continuously reducing since the 1950s, as well as the maximum snow water equivalent. And ice period of the Eurasian rivers has shortened about 24 days. The LD trend is mostly dominated by temperature via impacting river ice thickness and extent, while the HD is mostly impacted by snowmelt water and rainfall respectively in different latitudes. Annual MD trend is controlled by evapotranspiration, especially after the late 1990s. After the late 1990s, a warm Arctic-large discharge pattern existed in the lower and high latitudes of Eurasia, but a warm Arctic- few discharge pattern in the middle latitudes (except the winter).