IHCantabria research reveals how water mixes and stratifies in the Suances estuary
The Suances estuary is a natural area of the coast of Cantabria, flanked by fine sandy beaches; it is formed by the mouth of the Saja and Besaya rivers
Understanding how river and marine waters mix in estuaries is key to their conservation and sustainable management, especially in a context of climate change and increasing human pressure
Researchers from the Environmental Hydraulics Institute of the Universidad de Cantabria (IHCantabria) have recently published, in the journal Frontiers in Marine Science, the results of a study that has examined, for the first time, the mechanisms that regulate mixing and stratification in the Suances estuary, located in Cantabria, northern Spain.
Characterized by its small size and large intertidal zones, the Suances estuary has complex mixing patterns due to the interaction of tidal and fluvial inputs. Understanding these processes is essential for the protection and recovery of the ecosystem services provided by estuaries.
The study used a three-dimensional hydrodynamic model to calculate the potential energy anomaly and its derivative, tools to assess the competition between mixing and stratification in the water column. The results of this study revealed that the variability in mixing and stratification is mainly driven by three factors: river flow, which determines a seasonal cycle with monthly variations; tidal phase, which influences a daily cycle associated with ebb and flow phases; and tidal magnitude, which generates a fortnightly cycle, related to neap and neap tides.
The study developed by IHCantabria researchers also identified the predominant mechanisms affecting estuarine dynamics. Deformation(straining) tends to stratify the estuary, while horizontal transport in the water column, due to water movement (advection), favors mixing. In turn, nonlinear deformation, generated by intertidal areas, can promote both mixing and stratification according to tidal cycles.
An outstanding conclusion of the study is “the identification of a threshold between the potential energy anomaly and the depth of the water column, which indicates that there are limiting values of stratification, depending on the depth. This is especially relevant in small and shallow estuaries, such as Suances”, explains Javier F. Bárcena Gómez, one of the co-authors of the article recently published in the journal Frontiers in Marine Science and co-director of the doctoral thesis developed by Jagoba Lupiola, first author of this article.
This work not only provides a detailed understanding of the physical processes in estuaries of similar characteristics, but “also offers an innovative methodology that can be applied in the management and conservation of these ecosystems, which are fundamental for biodiversity and water quality”, says Andrés García Gomez, head of the Oceanography, Estuaries and Water Quality Group at IHCantabria, co-author of the aforementioned article and co-director of Jagoba Lupiola’s doctoral thesis.
For more information, you can access the full article published in the journal Frontiers in Marine Science.
Support staff of the research conducted by IHCantabria in the Suances estuary
The researcher Javier F. Bárcena in the estuary of Suances
