Modelling the effects of sea-level rise and sediment budget in coastal retreat at Hermenegildo Beach, Southern Brazil

Abstract

Climate change effects such as accelerated sea-level rise, wave climate alteration and disturbances on sediment-budgets are anticipated to lead to a range of adverse impacts in coastal regions around the world. A rise in sea-level is expected to cause shoreline recession, and a sediment deficit can have a similar effect. Since large uncertainties exist in relation to sea-level rise rates and sediment budgets, it is relevant to determine how sensitive the coast is to each of these disturbances. In this context, this paper provides a quantitative evaluation of each of these parameters in terms of modeled coastal recession through risk-based assessments using an aggregated coastal model, the DRanSTM (Dilating Random Shoreface Translation Model). In each separate computer simulation, a sediment budget and a sea-level scenario were set for an erosional coastal stretch: Hermenegildo Beach, Rio Grande do Sul state in southern Brazil. Effects of changes in wave climate were not directly considered in this study. However, indirect measures of such changes should be reflected on coastal sediment budgets. Simulation results demonstrate that under present-day sea-level rise rates, sediment deficit exerts control over coastal recession. Conversely, under the higher forecasted sea-level rise for the year 2100, mean shoreline recession will be dictated by sea-level rise, considering historical sediment deficit will be sustained.

Free and Open-Source Software for Geographic Information System on Coastal Management: A Study Case of Sea-Level Rise in Southern Brazil

“…The results given by the BRGM exceeded the retreat predicted in Hermenegildo in comparison to those obtained with the Random Shoreface Translation Model (RanSTM) [73][74][75][76]. [73] obtained a mean retreat distance of -521 m for 2100 using sea-level projections provided by the IPCC 2007-AR4.…”

Development of Tools for Coastal Management in Google Earth Engine: Uncertainty Bathtub Model and Bruun Rule

“…The coast is wave-dominated, and tides have a subordinated role in coastal hydrodynamics and present a mean amplitude of 0.5 m and a maximum of 1.2 m. The wave climate is dominated by two-wave propagation patterns, one composed of S-SE swell waves of higher amplitude and longer periods; the second comprising locally generated waves, with shorter periods and a predominant E-SE direction. Swell waves have a mean significant wave height of 1.5 m and periods of 12 s. Sea waves are characterized by a mean significant wave height of 1 m and a mean period of 8 s [27]. The continental shelf is wide (100 to 200 km), shallow (100 to 140 m) and slightly sloping (0.02 • to 0.08 • ) [26].…”

Os efeitos da elevação do nível do mar e do balanço sedimentar em um hotspot erosivo no litoral do Rio Grande do Sul, Brasil

“…Dillenburg et al (2000Dillenburg et al ( , 2003 apontam que a evolução costeira do RS durante os últimos 5 ka foi conduzida, sobretudo, pelo BS, quando o nível do mar estava abaixando. Figueiredo et al (2018) Tabela 2. Valores de distâncias e taxas de recuo para 50 e 1% de risco, para 2041 e 2100, para a Célula Costeira.…”

“…11B), devido a maiores taxas de ENM esperado para 2100. Figueiredo et al (2018) simularam o efeito individual da ENM e do BS na praia do Hermenegildo para 2100, usando os dados do IPCC para ENM, RCP 2,6 (menor taxa de ENM) e RCP 8,5 (maior taxa de ENM), constataram que a ENM passa a controlar a e evolução costeira, correspondendo a 79 e 85% do recuo da LC respectivamente.…”