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Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 13, 465-482, 2017
https://doi.org/10.5194/os-13-465-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
15 Jun 2017
Small river plumes off the northeastern coast of the Black Sea under average climatic and flooding discharge conditions
Alexander Osadchiev1 and Evgeniya Korshenko2 1Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
2Zubov State Oceanographic Institute, Moscow, Russia
Abstract. This study focuses on the impact of discharges of small rivers on the delivery and fate of fluvial water and suspended matter at the northeastern part of the Black Sea under different local precipitation conditions. Several dozens of mountainous rivers flow into the sea at the study region, and most of them, except for several of the largest, have little annual runoff and affect adjacent coastal waters to a limited extent under average climatic conditions. However, the discharges of these small rivers are characterized by a quick response to precipitation events and can significantly increase during and shortly after heavy rains, which are frequent in the considered area. The delivery and fate of fluvial water and terrigenous sediments at the study region, under average climatic and rain-induced flooding conditions, were explored and compared using in situ data, satellite imagery, and numerical modeling. It was shown that the point-source spread of continental discharge dominated by several large rivers under average climatic conditions can change to the line-source discharge from numerous small rivers situated along the coast in response to heavy rains. The intense line-source runoff of water and suspended sediments forms a geostrophic alongshore current of turbid and freshened water, which induces the intense transport of suspended and dissolved constituents discharged with river waters in a northwestern direction. This process significantly influences water quality and causes active sediment load at large segments of the narrow shelf at the northeastern part of the Black Sea compared to average climatic discharge conditions.

Citation: Osadchiev, A. and Korshenko, E.: Small river plumes off the northeastern coast of the Black Sea under average climatic and flooding discharge conditions, Ocean Sci., 13, 465-482, https://doi.org/10.5194/os-13-465-2017, 2017.
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Short summary
This study shows how intense rainfall at the steep and narrow catchment area of the northeastern part of the Black Sea can cause flash-flooding events and significantly influence coastal water quality. They change the point-source spread of continental discharge, dominated by several large rivers, to the line-source discharge from numerous small rivers located along the coast and induce intense alongshore transport of suspended and dissolved constituents discharged with river waters.
This study shows how intense rainfall at the steep and narrow catchment area of the northeastern...
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