Hydrodynamic and Waves Response during Storm Surges on the Southern Brazilian Coast: A Hindcast Study

Abstract

The Southern Brazilian Coast is highly susceptible to storm surges that often lead to coastal flooding and erosive processes, significantly impacting coastal communities. In addition, climate change is expected to result in expressive increases in wave heights due to more intense and frequent storms, which, in conjunction with sea-level rise (SLR), has the potential to exacerbate the impact of storm surges on coastal communities. The ability to predict and simulate such events provides a powerful tool for coastal risk reduction and adaptation. In this context, this study aims to investigate how accurately storm surge events can be simulated in the Southwest Atlantic Ocean employing the coupled ADCIRC+SWAN hydrodynamic and phase-averaged wave numerical modeling framework given the significant data scarcity constraints of the region. The model’s total water level (TWL) and significant wave height (Hs) outputs, driven by different sources of meteorological forcing, i.e., the Fifth Generation of ECMWF Atmospheric Reanalysis (ERA 5), the Climate Forecast System Version 2 (CFSv2), and the Global Forecast System (GFS), were validated for three recent storm events that affected the coast (2016, 2017, and 2019). In order to assess the potentially increasing storm surge impacts due to sea-level rise, a case study was implemented to locally evaluate the modeling approach using the most accurate model setup for two 2100 SLR projections (RCP 4.5 and 8.5). Despite a TWL underestimation in all sets of simulations, the CFSv2 model stood out as the most consistent meteorological forcing for the hindcasting of the storm surge and waves in the numerical model, with an RMSE range varying from 0.19 m to 0.37 m, and an RMSE of 0.56 m for Hs during the most significant event. ERA5 was highlighted as the second most accurate meteorological forcing, while adequately simulating the peak timings. The SLR study case demonstrated a possible increase of up to 82% in the TWL during the same event. Despite the limitations imposed by the lack of continuous and densely distributed observational data, as well as up to date topobathymetric datasets, the proposed framework was capable of expanding TWL and Hs information, previously available for a handful of gauge stations, to a spatially distributed and temporally unlimited scale. This more comprehensive understanding of such extreme events represents valuable knowledge for the potential implementation of more adequate coastal management and engineering practices for the Brazilian coastal zone, especially under changing climate conditions.

Ciclones extratropicais

“…Como os ciclones causam ventos intensos, o efeito sobre as águas oceânicas é de torná-las agitadas, com ondas de maior altura, transporte de água (storm surges ou pista de ventos) e empilhamento na região costeira (da , Candella & Souza, 2013, Machado & Calliari, 2016, Lima et al, 2020. Por exemplo, Parise et al (2009) descrevem a ocorrência de marés meteorológicas e erosão costeira no extremo sul do Brasil associadas com ocorrência de ciclones extratropicais sobre o oceano.…”

Identification of coastal natural disasters using official databases to provide support for the coastal management: the case of Santa Catarina, Brazil

“…The coast trends from south to southwest for approximately 430 km, and contains 922 km of open coast and bay shoreline, with 246 sandy beaches occupying 60% of the shore (Klein et al 2016). In the state, about 1,417,089 (22.7%) of the total 6,248,436 inhabitants are located in these municipalities (IBGE, 2010), where coastal natural disasters are frequently recorded (Klein et al 1999;Horn Filho 2006;Klein et al 2006;Santos 2007;CEPED UFSC 2013;Herrmann 2014;Klein et al 2016;CPRM, 2018;Dalinghaus et al 2018;Muehe 2018;Leal et al 2019;Silveira et al 2019;Leal et al 2020;De Lima et al 2020;Furtado and Bonetti 2021;Pazini et al 2021). The geological, geomorphological, climatic, sedimentary, and oceanographic characteristics of the study area can be found in detail in the study by Klein et al (2016).…”

“…These strong winds caused waves of two to three meters high between the municipalities of Florianópolis and Passo de Torres and, added to the high tide, caused the sea level to rise, thus the accumulation of water on the coast (CEPED UFSC 2013). The year 2017 was marked by consecutive and severe coastal natural disasters along with the state of SC, also associated with cyclonic formations in the South Atlantic and syzygy tides(De Lima et al 2020;Leal et al 2020).…”

Hydrological-hydrodynamic simulation and analysis of the possible influence of the wind in the extraordinary flood of 1941 in Porto Alegre

“…For these reasons, the 1941 flood is a traumatic at almost unique event in the history of Rio Grande do Sul, even though the state has a history of disasters that includes droughts (Kulman et al, 2014;Cunha et al, 2019), landslides (Froude & Petley, 2018;Cardozo et al, 2021), extreme winds (Machado & Calliari, 2016;Lima et al, 2020), hail (Nedel et al, 2012;Martins et al, 2017) and frequent floods that can occur practically at any time of the year (Cassalho et al, 2019).…”