ИСТИНА

Tidal river mouths are very complicated objects for hydrological and ecosystem research. Moreover, river mouth areas are characterized by unique and vulnerable ecosystems with great biodiversity. Water quality and hydrological monitoring is essential for their preservation in conditions of intensive water use. We provided comprehensive field observations of the flow dynamics in the Onega River estuary during winter and summer period. Field data analysis has shown flow velocity and flow direction variability over a tidal cycle and depending on river runoff, wind conditions and ice cover. We investigated flow velocity profiles and cross-section velocity distribution over a tidal cycle. Also, water levels and salinity were measured over a tidal cycle at multiple locations along the estuary. All the collected data can be used for designing an ecosystem monitoring program and setting up a hydrodynamic model of the Onega River estuary.