Aina Barcelona, Teresa Serra and Jordi Colomer, members of the Environmental Physics Research Group, publish the paper entitled “Fragmented Canopies Control the Regimes of Gravity Current Development” in the Journal of Geophysical Research: Oceans, which publishes original research articles on the physics, chemistry, biology and geology to the oceans and their interaction with other components of the Earth system.

This paper is result of the final degree project of Aina Barcelona, directed by Teresa Serra, and has been developed within the framework of the “Water Quality and Particles Transport” research line. The authors point out that coastal ecosystems (marine littoral regions, wetlands, and deltas) are regions of high biological productivity. However, they are also one of the world's most threatened ecosystems. Wetlands are characterized by aquatic vegetation adapted to high salinity levels and climatic variations. Wetland canopies buffer these hydrodynamic and atmospheric variations and help retain sediment by reducing current velocity during sea storms or runoff after periods of rain. This work focuses on the effect of the presence of a gap (i.e., nonvegetated zone) parallel to the direction of the main current has on the sedimentation and hydrodynamics of a gravity current. The study aims to (1) address the behavior of a gravity current in a vegetated region compared to one without vegetation (i.e., the gap), (2) determine the effect gap size has on how a gravity current evolves, and (3) determine the effect gap sizes have on the sedimentary rates from a gravity current. Laboratory experiments were carried out in a flume using four different sediment concentrations, four different canopy densities (884, 354, 177, and 0 plants·m^-2) and three different gap widths (H/2, H, and 1.5H, where H is the height of the water). This work shows that a gravity current's evolution and its sedimentary rates depend on the fractional volume occupied by the vegetation. While current dynamics in experiments with wider gaps are similar to the nonvegetated case, for smaller gaps the dynamics are closer to the fully vegetated case. Nonetheless, the gravity current exhibits the same behavior in both the vegetated region and the gap.

This project has been funded by the University of Girona through grant MPCUdG2016-006 and by the Ministerio de Economía, Industria y Competitividad of the Spanish Government through the grant CGL2017-86515-P (FragmentUm project).