The Cartographic Investigation Method for Identifying the Zonal Features in Riverbeds and Floodplains of the Asian Part of Russia, Mongolia and China

Abstract

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.