ИСТИНА

River channel lateral deformations associated with changes of their planform can impose serious threats to humans. Major hazards are associated with bank erosion and alluvial bedform migration. Constructions and communications located within channel or on its banks can be damaged or destroyed. In extreme cases buildings of towns can be washed away by a river. Migration of alluvial bedforms can result in blocking water intakes, fairways, ports and marinas. In other cases, alluvium can be eroded from bases of different constructions, and such objects lose integrity or totally collapse. Rates of bank erosion and bedform migration depend on river sizes. Banks of medium and large rivers are eroded at rates up to 5-10 m/year. Sandy dune bedforms can shift up to hundreds of meters over the warm season. On small rivers bank erosion is about 0.3-0.7 m/year, while bedform migration for those is not important. Bank erosion occurs only during spring snowmelt floods and rainfall-induced high-water periods. At the peak stage of rising water level and discharge banks collapse at the maximum possible rates. Assessment of geographic distribution of geomorphic hazards associated with river channel processes in Russia we used mapping method at the scales of the entire country and in separate river basins. These maps show the regions with increased, moderate and low levels of hazard with regard to bank erosion alluvial bedforms migration. Detailed characteristics of the hazard, the magnitude of its manifestations and potential consequences for bank and within-channel constructions are included in legends of such maps. Combination of the potential hazards of channel processes at various scales with information on existing or planned development within river or the riparian zone allows to evaluate risks of implementation of various land use types in river valleys.