Impact Of Mozhaysk Dam On The Moscow River Sediment Transport

Abstract

Sediments are an essential part of the aquatic environment that define its transformation and development. The construction of dams results in severe changes in sediment fluxes. This study aims to assess how the sediment load of the upper Moskva River is affected by the Mozhaysk Dam flow regulation and to estimate its dynamics over the years of the reservoir’s existence. Our analysis of the 1968, 2012 and 2016 detailed field data shows a 20-40% decrease in the proportion of the spring flood in the annual sediment load into the reservoir, which is caused by changes in the streamflow regime of the inflowing rivers. The peak suspended sediment concentrations have decreased 5- to 10-fold, likely due to a significant decline in the watershed’s cultivated land area, which caused a decrease in the erosion rate. In the Moskva River below the dam, the seasonal dynamics of the suspended sediment concentration no longer corresponds to the natural regime. The annual suspended load of the Moskva River below the Mozhaysk Reservoir decreased up to 9-fold. The sediment retention in the reservoir has dropped from 90% to 70-85% and is to some extent restored by an outflow of the particulate organic matter produced in the reservoir. We also described the relationships between water turbidity and suspended sediment concentration of the reservoir’s tributaries, which allow for the first time to estimate the sediment load with higher accuracy than was previously possible.

River Damming Impacts on Fish Habitat and Associated Conservation Measures

“…Low sediment loads downstream after dam construction also leads to reductions in associated nutrient transport, and thus affects fish feeding grounds (C. Guo et al., 2020). Moreover, the balance between inorganic and organic sediment is disrupted by damming, with mineral particles deposited predominately in the reservoirs, and the increased biological production causing the suspended load of the reservoir outflow to be largely composed of organic matter from aquatic organisms (Sokolov et al., 2020).…”

Efficacy of Synthetic Sediment Graph Developed using Various Modified Time-Area Methods

“…The spatio-temporal analysis of sediment yield is needed for watershed management, especially for soil and water conservation and watershed health assessment (Sadeghi et al 2019;Hazbavi et al 2020;Mirchooli et al 2021). The amount of SS produced in a watershed depends on the distribution and duration of precipitation, sediment availability, flow velocity, geomorphology, land cover and human activities (Seeger et al 2004;Messina and Biggs 2016;Rahaman and Solavagounder 2020;Sokolov et al 2020;Waiyasusri and Wetchayont 2020;de Paula et al 2021). Most watershed management studies provide general estimates of soil erosion using empirical or non-distributed models such as Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), and Water Erosion Prediction Project (WEPP) (Wischmeier and Smith 1978;Sadeghi and Mizuyama 2007;Srivastava et al 2020;Zheng et al 2020).…”