Changes in conditions of interaction of ground, river and swamp water during swamping of the West Siberian plain in the Holocene

Abstract

Relevance. The need to understand and long-term forecast the conditions of interaction between groundwater, river and swamp waters in the Ob River basin. Aim. To identify patterns of changes in the conditions of interaction of groundwater, river and swamp waters during swamping of the flat part of the Ob River basin in the Holocene. Methods. Mathematical modeling methods, statistical methods, geographical-hydrological method. Results and conclusions. The author has carried out an analysis of materials from long-term hydrogeological and hydrological observations in the wetlands of the Ob basin and studied the hydrodynamic and geochemical conditions for interaction of groundwater, river and swamp waters. It is shown that the emergence and evolution of swamp ecosystems in the territory under consideration is a complex of erosion-accumulation processes, the development of which until the modern period took place in three stages: 1) from the beginning of intense degradation of glaciation to 4...6 thousand years ago is the formation of a primary hydrographic network approximately modern appearance, distribution of peat bogs; the groundwater regime is close to the groundwater regime of the permafrost zone in the north of modern Western Siberia; 2) from 4...6 thousand years ago to 1.5...3 thousand years ago is large-scale distribution of lowland swamps and degradation of part of the primary river network; groundwater levels in river watersheds are generally lower than at present, but the amplitude of their fluctuations is high; a significant part of the watersheds are flooded during high water and floods, and underflooded during low water periods; 3) from 1.5...3 thousand years ago is degradation of a significant part of the primary river network, wide distribution of raised swamps, formation of a secondary hydrographic network in the swamps; at watersheds, groundwater levels rise, but the amplitude of their fluctuations decreases, and water exchange with swamps is significantly reduced; in the valleys of medium and large rivers, water exchange between surface and groundwater is most intense, which causes the flow of significant amounts of organic substances and products of their transformation into river and groundwater from swamps. Scenarios of possible changes in the conditions of interaction between surface and groundwater were assessed.