Future Sea Level Rise and Changes on Tides in the Patagonian Continental Shelf

We investigate the effect of the future sea level rise (SLR) on the propagation of tides in the Patagonian Shelf by means of numerical simulations. Using a barotropic implementation of the Model for Applications at Regional Scales (MARS), we obtain solutions for scenarios which represent the present condition and potential future SLRs of 1, 2, and 10 m. The effect of flooding of low-lying areas is studied, and its influence on the propagation of tides in the region is discussed. Due to the coastal morphological features and the sense of tidal wave propagation in the Southern Hemisphere, inundation does not significantly modify the solution in the Patagonian Shelf; nevertheless, results are substantially changed in the much lower Northern Argentinean Shelf, north of 40 degrees S, where dissipation is increased. The amplitude of M-2 responds to SLR in a spatially nonuniform manner. The response is nonlinear, particularly in regions close to the amphidromic points. Tidal dissipation by bottom friction increases consistently by 16% for the more extreme scenario with a generalized increment of tidal amplitudes, and therefore currents, over the Patagonian Shelf. Changes in the extension and position of tidal fronts are also explored. The results suggest that changes will be significant, with a reduction of the mixed areas in Cabo Blanco and San Sebastian and an increment of them in the vicinity of Peninsula Valdes. Physical mechanisms that explain the observed modifications in the tidal regime are the changes with SLR of the speed of the tidal wave, the Rossby radius of deformation, the energy dissipation by bottom friction, and the resonant properties of the basin. Similarly to numerical studies performed for other coastal areas of the world, results indicate that important changes in the characteristics of tides can occur if SLR is large.