Future sea level rise and changes on tides in the Patagonian Continental Shelf

Abstract

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 MARS model, we obtain solutions for scenarios which represent the present condition and for potential future SLRs of 1, 2 and 10 m. The effect of flooding of low-lying land 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 propagation of the tidal wave 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 40º S, where dissipation is increased. The amplitude of M2 responds to SLR in a spatially non uniform manner. The response is non linear, particularly in the regions close to the amphidromic points. Tidal dissipation by bottom friction increases by 16% for the more extreme scenario consistently with a generalized increment of tidal amplitudes, and therefore currents, over the Patagonian Shelf. The changes in the extension and position of the tidal fronts are also explored. Results suggest that changes will be significant, with a reduction of the mixed areas in Cabo Blanco and San Sebastián and an increment of them in the vicinity of Península Valdés. The physical mechanisms which 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 ocean, results indicate that important changes in the characteristics of the tides can occur if the SLR is large.