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Climate transition at different scales complicates the dynamics of catchment water cycle. Examination of meteorological pattern shift enables us to have a deeper insight of the mechanism in hydrological extremes. Lake Hulun, the largest freshwater lake in Northern China, plays an important role in maintaining the regional ecological sustainability. The abrupt decrease of water level in the lake after 2000 has resulted in serious impacts on the lake's ecosystem. This paper presents a systematic analysis by linking meteorological dynamics with hydrological extremes based on the long-term precipitation, river discharge, and evapotranspiration (ET) data in the Lake Hulun watershed, which is a transition zone from desert to wetland and to permafrost along the Mongolia–China borderline. The results indicate that signals of large-scale precipitation variations can be well identified by using the Empirical Orthogonal Function (EOF). Spatially, the precipitation in the Lake Hulun watershed is dominated by two leading EOF patterns at the basin scale. The two leading patterns present complementary features of the high value centers in space. The amplitudes evolution of the leading patterns of EOF reveal that the redistribution of precipitation that occurred more in the middle flat plain and less in the mountain regions of the watershed triggers a big effect on the increasing ET and weakening runoff production due to the spatial heterogeneity in hydrological processes. Such effects are echoed by the trend patterns in precipitation and ET. The mechanism of the precipitation pattern shift is also confirmed by the large scale meteorological variations in geopotential and water vapor transport. Therefore, the change in the leading patterns of precipitation and the effects in ET triggered by the pattern shift in precipitation are the major causes of decrease in watershed runoff and the hydrological extremes in the terminal lake. [ABSTRACT FROM AUTHOR]

This article deals with the features in the morphology and dynamics of river beds and floodplains located in different natural zones and in different conditions of development of channel deformations. In preparing small-scale thematic maps (geomorphological, landscape and other maps), river valleys and their constituent river beds and floodplains are displayed in a simplified fashion using a common linear conventional sign. However, the procedure neglects the influence on the formation and development of riverbeds and floodplains from zonal processes associated with climatic features of river basins. For revealing this influence, an original small-scale map of riverbeds on a large territory of the East of the Eurasian continent covering the Asian part of Russia, Mongolia and China (Eastern transect), was compiled. The climatic zonality of both plains and highlands is widely manifested in this territory and the influence of zonality on intrazonal channel processes is emphasized. Of course, the leading factors are fluvial, but they are actively influenced by zonal natural factors. In the nival zone, they are represented by cryogenic processes, and in the semiarid zone by aeolian and halogen processes (salinization of floodplains). In the highlands, the role of horizontal zonality is less (it is manifested only in the semiarid highlands), but there the influence of azonal slope processes is intensified. Only in the humid zone, the nonfluvial factors of channel and floodplain processes are almost not manifested. The identified regularities are associated with the occurrence of dangerous emergency and extreme channel processes which differ in their specificity in each natural zone. This should be taken into account when mapping them and using river resources. [ABSTRACT FROM AUTHOR]