THE RESISTANCE OF RIVERBEDS IN THE URAL RIVER BASIN TO SILTING

Abstract

The study examines the resistance of river channels in the Ural River basin to siltation processes developing under the combined influence of natural and anthropogenic factors in the context of current and projected climatic changes. Special attention is given to the impact of the anticipated reduction in river water yield as well as to the potential intensification of agricultural development within the catchments, which may significantly increase the supply of fine sediments to the fluvial network. The study has established that the reduction of channel-forming discharges leads to a decrease in the sediment-transport capacity of the flow and, consequently, accelerates sediment accumulation, particularly in the upper segments of the river system and in small watercourses characterized by limited water discharge. It is shown that rivers with incised channels, significant longitudinal slopes, and narrow floodplains – which maintain high hydraulic power – demonstrate the greatest resistance to siltation. In contrast, wide-floodplain rivers and reaches with low runoff yield exhibit the highest sensitivity to disturbances of channel dynamics and reductions in water availability. The projected 15–20% decline in river discharge by the mid-21st century may lead to an expansion of areas vulnerable to siltation, reinforcing the need to develop adaptive approaches to water-resource management, including anti-erosion measures within agriculturally developed basins. The results obtained may serve as a basis for scientifically grounded decision-making in the field of rational water-resource use, prevention of channel degradation, and spatial planning of environmental protection measures aimed at maintaining the functional stability of the hydrographic network of the Ural basin under climatic and anthropogenic change.