Assessing Flood Risk Under Sea Level Rise and Extreme Sea Levels Scenarios: Application to the Ebro Delta (Spain)

Abstract

This study presents a novel methodology to estimate the impact of local sea level rise and extreme surges and waves in coastal areas under climate change scenarios. The methodology is applied to the Ebro Delta, a valuable and vulnerable low‐lying wetland located in the northwestern Mediterranean Sea. Projections of local sea level accounting for all contributions to mean sea level changes, including thermal expansion, dynamic changes, fresh water addition and glacial isostatic adjustment, have been obtained from regionalized sea level projections during the 21st century. Particular attention has been paid to the uncertainties, which have been derived from the spread of the multi‐model ensemble combined with seasonal/inter‐annual sea level variability from local tide gauge observations. Besides vertical land movements have also been integrated to estimate local relative sea level rise. On the other hand, regional projections over the Mediterranean basin of storm surges and wind‐waves have been used to evaluate changes in extreme events. The compound effects of surges and extreme waves have been quantified using their joint probability distributions. Finally, offshore sea level projections from extreme events superimposed to mean sea level have been propagated onto a high resolution digital elevation model of the study region in order to construct flood hazards maps for mid and end of the 21st century and under two different climate change scenarios. The effect of each contribution has been evaluated in terms of percentage of the area exposed to coastal hazards, which will help to design more efficient protection and adaptation measures.

Coastal Impacts Driven by Sea-Level Rise in Cartagena de Indias

“…Therefore, to take the most appropriate mitigation and adaptation measures, it is necessary to perform local studies accounting for all physical variables to determine the impact of SLR over the coastal zones. Sayol and Marcos (2018), estimated the impact of local sea level rise, extreme surge and waves in the Ebro Delta (Spain) under the climate change scenarios RCP4.5 and RCP8.5. The results show that for the year 2050 under the RCP 4.5 and RCP 8.5 sea level rise will flood a 65% of the Delta in both cases.…”

“…Then, correlation is assessed with the Kendall rank correlation. Previous studies in the US coast and globally have suggested that an indicative value of 0.2 may be already significant enough (Wahl and Chambers, 2014) to require the computation of the joint probability using a multivariate approach such as the Copula functions (e.g., Sayol and Marcos, 2018;Enríquez et al, 2019;Marcos et al, 2019). Correlations for those independent events are shown in Figure 4C for all percentiles being in all cases very low with FIGURE 5 | Schematic representation of the approach followed in the study.…”

“…Some studies determined the wave run-up on beaches during normal and extreme conditions without considering the role of the SLR (e.g., Callaghan et al, 2009;Dietrich et al, 2011;Peláez-Zapata et al, 2012;Andrade et al, 2013;Fleming et al, 2013) and, only since recently, the combined effect of SLR and extreme events under greenhouse scenarios has been assessed (e.g., Masselink et al, 2016;Mentaschi et al, 2017;Melet et al, 2018;Sayol and Marcos, 2018).…”

Increased Extreme Coastal Water Levels Due to the Combined Action of Storm Surges and Wind Waves

“…Here we have selected the most probable pair of surge‐ H s . This approach was also applied in Sayol and Marcos () for a local case study.…”

Assessing Beach and Dune Erosion and Vulnerability Under Sea Level Rise: A Case Study in the Mediterranean Sea

“…Given the threats that climate change and the associated SLR pose to the coastal regions, the assessments of future coastal vulnerability have become topic research issues in the last years (Nicholls, 2002;Revell et al, 2011;Idier et al, 2013;Le Cozannet et al, 2014;Ranasinghe, 2016;Luijendijk et al, 2018;Sayol and Marcos, 2018) as well as their socio-economic consequences (Small and Nicholls, 2003;Dasgupta et al, 2009;Gössling et al, 2012). Among these, studies focused on sandy shores, mostly beaches, are very common because this type of coasts is subject to a very high level of human utilization (Gössling et al, 2012).…”