Analysis of Different Protocols for the Artificial Opening of the Laguna de Rocha Inlet

Abstract

Teixeira, M. and Solari, S., 2020. Analysis of different protocols for the artificial opening of the Laguna de Rocha inlet. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 958–962. Coconut Creek (Florida), ISSN 0749-0208.Laguna de Rocha is an intermittent opening and closing lagoon (ICOLL), located on the Atlantic coast of Uruguay. The lagoon closes practically every year during the warm months and, in general, it is artificially opened during the cold months to avoid floods and to facilitate the exchange of water, substances and organisms with the ocean. A consensus among stakeholders has been reached recently for a protocol stablishing when to open the lagoon, as previously there was no protocol at all (Conde et al., 2019). However, an analysis of how the possible opening protocols affect the hydrodynamic response of the lagoon and its exchanges with the ocean in the mid and long term is still required. Following previous researches, a simplified, physics-based model was developed for analyzing time evolution of the hydro- and morpho-dynamics of the inlet. The model resolves the opening and closing processes as well as the water level variations in the lagoon. Sensitivity of the model to several parameters and comparison with available field data was carried out first. Then, the model was used for analyzing how the lagoon responds in the mid to long term (i.e. years) to different artificial opening protocols. The response of the lagoon was quantified with several metrics, namely: number of openings per year, amount of water exchanged between the lagoon and the ocean, extent and frequency of flooded areas. Two benchmark protocols are used for comparison purposes: the current protocol defined in Conde et al. (2019) and a no-intervention protocol.