Comparative analysis of bottom sediments of the Cheremshansky bay and the Dammed ples of the Kuibyshev reservoir

Different types of underlying surface of Kuibyshev reservoir watershed, morphometric heterogeneity and active hydrodynamic regime of water area determine also different composition of bottom sediments and content of organic matter in different parts of this water body. Comparative analysis of integral curves of particle-size composition of bottom sediments of Priplotinny ples and Cheremshanskiy bay showed a significant difference in the parameters of these curves. The analysis is based on the soil maps of the catchment area, bathymetric maps, the distribution field of the bottom sediments coarseness and the share of organic matter in them, as well as the velocity fields obtained as a result of hydrodynamic modeling of the water area. Comparable water areas differ fundamentally in the intensity of water exchange. Prilotinny ples is more hydrodynamically active water area, whereas Cheremshansky bay is characterized by extremely slow water exchange. At the same time, the private catchment of the tribe is represented by easily eroded light loams, dolomites and limestones. While the upper part of the private catchment area of the bay is heavily forested, and the lower part of the catchment area is composed of medium and heavy loams. All this determined the formation of bottom sediments (in the form of fine and medium sands) by bedrock and products of channel erosion of the upper and middle sections of the hydrographic network of the Cheremshanka River. Whereas fine-dispersed products of soil erosion in the private watershed of the tribe formed the bottom sediments, represented mainly by silt-silt fractions. Also well warmed extensive shallow water area of the bay creates favorable conditions for mass development of plankton community, its die-off and sedimentation in the form of detritus to the bottom. Whereas greater depth and active hydrodynamics of water masses in the Priplotinny ples determine lower content of organic matter in bottom sediments. The greatest amount of detritus is carried by current from shallow water zones and is deposited in the deep central and right bank part of the tribe.