Estimation of the runoff elasticity of the rivers in the eastern part of the Amur River basin

Taking into account the unstable moisture regime and the diversity of landscapes within the Amur River basin, the problem of assessing the impact of climatic changes on the processes of surface water cycle in the region becomes multifaceted, associated with the solution of particular problems. This work studied the reaction of a river runoff to changes in the amount of atmospheric precipitation on the basis of the elasticity coefficient. Small and medium-sized river basins (52 in total) belonging to the system of the Middle and Lower Amur are the objects of this study. The data of standard observations at hydrological posts and meteorological points for the summer-autumn flood hazard period (June-September) were used. The data series were selected to include different moisture conditions. It was found that with an increase in precipitation by 1%, the river runoff in the flood hazard season has increased by 1.02–3.86% in 48 cases, and decreased in 4 cases. The results of the work are fundamentally close to the regional estimates within the basin of the Amur River on the base of the analysis of factual material (including the near abroad) and simulation results, as well as to the values of the runoff elasticity coefficient obtained in different geographic zones and given in the specialized literature. The relationship between the elasticity coefficient values of runoff with various basin indicators has been studied. For the rivers in the Primorsky Kray (catchment area of the Ussuri River), the relationship between the elasticity coefficient values and the seasonal runoff and precipitation, the runoff coefficient, average height, catchments slopes and average river network slopes has been revealed. The influence of local conditions of runoff formation on the river basins response to changes in the amount of atmospheric precipitation is discussed.