Hydrophysical Characteristics of Lake Manzherok after Dredging

Data on seasonal and long-term dynamics of hydrophysical characteristics in the water area of Lake Manzheroksky (Altai Republic) after dredging in 2017–2018 are presented. The expedition studies were conducted during the ice age in April 2021, as well as the summer warming of the lake in July 2021 and 2023. The spectral index of light attenuation in the range of 400–800 nm, the relative transparency of water over a white disk, the velocity of water movement in surface and bottom horizons, as well as temperature stratification are studied. It was found that the discovered bottom groundwater sources contributed to the erosion and dissolution of the not completely removed silt layer, which determined high values of the spectral index of light attenuation and low relative transparency of the water. The research results in July 2023 showed significant changes in hydrophysical characteristics compared to 2021, indicating an improvement in the ecological condition of the lake in a long-term aspect for the period from 2018 to 2023. A comparison of spring and summer data on the dynamics of the spectral index of light attenuation at different depths for Lake Manzheroksky with other freshwater low-flow lakes showed that this hydro-optical parameter for the studied lake is maximum during the ice age, while for other lakes its minimum is noted in this phase of the annual limnic cycle.