Analysis of the Possible Consequences of Large-Scale Production of Sand and Gravel Mixture in the Downstream of Large Hydroelectric Facilities Based on Hydrodynamic Modeling (the Votkinsk HPP as an Example)

The authors have presented estimation of possible hydraulic consequences of the large-scale mining of sand/gravel mixtures in the upper part of the Lower Kama Reservoir 9the Votkinsk Reservoir downstream) based on the multi-version computation experiments with the developed hydro/dynamic model of the water body under consideration. This estimation is necessary for development of measures aimed at minimization of negative aftermath and provision of the interest balance between water users. Methods. The work is based on the conjugation of a set of field observations with computational experiments based on hydrodynamic models in 1D and 2D formulations, which make it possible to carry out hydrodynamic calculations for the waves of releases from HPPs. Results. The dynamics of water levels was investigated for various calculation scenarios, graphs were drawn for comparing water levels based on the results of calculations in one- and two-dimensional models for morphometry in 2019 in natural conditions and taking into account the development of deposits of sand and gravel mixtures. The experiments have demonstrated that development of only eight deposits (Volkovsk, Olkhovsk, Sivinsk, Golyanovo, Makarovsk, Upper-Dulesovsk, Simonikhinsk, and Simonikhinsk-2) will cause the necessity (in order to maintain the 3.3 m navigation depth) to increase the discharge to the Votkinsk HPP downstream up to 1800 m3/s or maintaining of continuous 1500 m3/s discharge for at least 24 hours. In the process of the water level graphs comparative analysis, both in one-dimension and two-dimension modeling, one can distinguish three sites with great level subsidence (15-41 cm) due to the large-scale mining of sand/gravel mixture.