Changes of natural processes in the Volga-Akhtuba floodplain and Balta braila of Lower Danube

In the second half of the twentieth century, the Volga and the Danube were regulated. As a result, channel processes and the processes of alluvium deposition and humus accumulation in soils, surface and underground waters were changed. The comparative analysis of Volga-Akhtuba and Lower Dunabe floodplains is carried out in the article. It was found that due to the regulated flow, hydraulic engineering and land reclamation construction had provoked direct (immediate) changes in natural systems, as well as indirect (mediated) changes in the landscapes. The Volga-Akhtuba floodplain is characterized by the dominance of indirect effects resulting from changes in the hydrological regime of the Volga to produce cheap electricity and irrigation of vegetable plantations. Therefore, the landscape can be attributed to the natural type. The Lower Danube is characterized by immediate impact, namely, leveling the surface and creating a drainage system, the purpose of which was to increase the area of agricultural land within the floodplain and to decrease the number of catastrophic floods. This led to the formation of technogenically anthropogenic landscape within the floodplain. The components and relationships in the downstream of the Volga hydroelectric are degraded, but not destroyed in comparison with the Great Balta Braila, so the natural complexes of the Volga-Akhtuba floodplain and associated natural processes can be restored by means of environmental management. Abnormalities in the flow regulation of the Volga and the Danube led to the destruction of hydraulic connection between the two bodies of water floodplains, alluvial processes slow down and change in the level of groundwater. Within the floodplain the erosion and accumulation also lowered their rates. The river channels, on the contrary, increased erosion and accumulation, causing the decrease of rivers level, and there is an active formation of braid, shoals and islands.