Costal sea level variability and extreme events in Moñitos, Cordoba, Colombian Caribbean Sea
Introduction
Scientific evidence indicates that the planet is warming and sea levels are rising (Shaftel et al., 2018), and this is expected to continue to occur despite a certain degree of uncertainty around trends (Le Cozannet et al., 2015). Studies based on climate models have found that the mean sea level could increase by up to 1 m or more by the year 2100 (Nicholls et al., 2014). The impact of sea level rise is expected to become more severe. Episodes of coastal flooding will likely increase due to the combination of sea level rise and variations in extreme weather events (Losada et al., 2013). This behavior will severely affect coastal settlements.
Coastal water levels and their variability result from multiple processes occurring on different time and space scales and their respective interactions. Chelton and Enfield (1986) identify nine processes that contribute to sea level variability: astronomical tides, the inverse barometer effect, geostrophic currents, coastal upwelling, coastal trapped waves, seasonal variability, low-frequency atmospheric forcing, the El Niño–Southern Oscillation (ENSO) phenomenon and secular variability. According to Chen et al. (2010), at a global scale sea level variability presents eleven main modes which can be classified into four regimes: seasonal (3 and 6 months), annual (12 months), inter-annual (1.55, 1.74, 1.94, 2.34, 3.07, 4.20 and 5.40 years) and decadal (9.28 years). Despite this classification, geographical variability depends on the local characteristics of the phenomena that contribute to coastal sea levels, such as wave conditions, winds, pressure or tidal range. These can be caused by different combinations of phenomena, such as storm surge conditions that occur often (Breilh et al., 2014; Cid et al., 2017).
About interannual variability of sea level, Valle-Levinson and Martin (2020), studied the influence of lunar precessions and solar activity periodicities in the moments of rapid sea level rise with periods greater than 5 years (referred as hot moments). The results show a high statistical explanation for maximum values of sea level rise when several harmonics are employed to reconstruct the signal for the coastal areas of the United States and the Gulf of Mexico. Other authors such as (Kristjansson et al., 2002; Barripedro et al., 2010; Martinez-Asencio et al., 2016, Kaniewski et al., 2016, among others) have shown the connection between this astronomical forcing and other physical processes affecting extreme sea level events, such as winds, tides, atmospheric pressure, daytime temperatures and cloud cover.
Coastal flooding is caused by a combination of different processes superimposed on global, regional and local scales. According to Rueda et al. (2017), in most coastal regions, floods are mainly dominated by the astronomical tide, with a 59% average global contribution. This is followed by wave set-up and storm surge, with average global contributions of 29% and 12% respectively. According to Melet et al. (2018), contributions related to waves (Setup and swash) are the most significant on interannual-to-multidecadal scales. Other authors have also reported on the importance of components associated with waves (Dada et al., 2020; Serafin et al., 2017; Wadey et al., 2017). Likewise, coasts have been identified where there are significant contributions from fluctuations in the mean sea level (Eliot, 2012). Therefore, although meteorological and oceanographic processes occur on a global scale, they have a diverse impact on the variability of sea level on both a temporal scale and on a spatial scale, with differences from one coast to another (Melet et al., 2018; Rueda et al., 2017).
In the Colombian Caribbean, the importance of how the different oceanographic processes contribute to coastal flooding is not well understood, and neither are the effects of spatial scales on the coastal sea level. This represents challenges for planning the development of coastal settlements and incorporating risk management of coastal flooding, for which an understanding of the variability and forcing factors is essential. Examples of the few studies carried out on the subject are those of Martínez (2010), who looked at several representative sites and proposed a methodology to estimate flood levels on the Colombian Caribbean coast, Losada et al. (2013), who studied sea level, its components and long-term trends for Latin American and Caribbean coasts, however with coarse resolutions. There are also, some local studies like Andrade et al. (2013) and Nicolae et al. (2008), who assessed flooding in Cartagena due to extreme events ('Mares de leva'), and Osorio et al. (2014) who evaluated the flood level at Playa Palmeras in the Colombian Pacific. More recently, research has been carried out by Orejarena-Rondón et al. (2018), who present a methodology for obtaining sea level regimes in microtidal areas with scarce data availability and apply it to Cartagena and the Gulf of Urabá, and Orejarena-Rondón et al. (2019), who studied the combined impact of extreme waves and sea level in Bocagrande, Cartagena. In these studies, coastal flooding was addressed using numerical models and reanalysis data due to the scarcity of measured data. However, climatic analysis and its relationship with macroclimatic phenomena or extreme events on several scales has not been studied in detail. Challenges related with long term changes in sea level rise, wave energy fluxes and atmospheric patterns as a consequence of climate change and climate variability should be explored on local scales, as affirmed by several authors (Casas-Prat et al., 2018; Mentaschi et al., 2017; Orejarena-Rondón et al., 2019).
In the literature, the study of coastal flooding has been addressed in various ways depending on the purpose, scale of interest and available data. Some are based on hydrodynamic models (Fernández et al., 2018; Yin et al., 2017) and 'static' approaches where flooding for each temporal scenario is obtained from the 'Total Water Level’ – TWL (Serafin and Ruggiero, 2014; Wang et al., 2017). In the latter approach, the different components of the flood are simulated independently through numerical models (Losada et al., 2013) and/or using empirical parameterizations for variables such as runup (Christie et al., 2017; Silva et al., 2017) and storm surge (Del Río et al., 2012; Maia et al., 2016). Some applications of the TWL estimate have also been performed using observational data such as in-situ wave buoy and tide gauge data (Serafin and Ruggiero, 2014). In coastal and oceanic areas of Colombia, marine climate information is scarce or is of low quality (Ortiz et al., 2014; Osorio et al., 2016). Conventional instrumentation such as wave buoys or tide gauges tend to be limited to certain strategic points like important ports or tourist areas, e.g. Cartagena and San Andrés. This limits the ability of scientists to study coastal flooding, which is why such studies are scarce in Colombia.
The aim of this paper is to analyze the behavior of the coastal sea level variability in Moñitos, in the municipality of Córdoba using the ‘Total Sea Level (TSL)’ approach. Variability at different time scales, the occurrence of extreme events, the relative contribution of different components and the incidence of the ENSO phenomena were studied. It is expected that this study will serve as a methodological proposal for the understanding of these processes in the other coastal regions in the great Caribbean and the Antilles islands. This paper is organized as follows: Section 2 presents a description of the study area, Section 3 gives a description of the materials and methods employed, Section 4 presents the results and discussion of flood variability, and conclusions are given in Section 5.
Section snippets
Study area
The Moñitos municipality is located on the Colombian Caribbean coast, in the vicinity of the Gulf of Morrosquillo (Fig. 1). The urban area of the municipality covers 22.9 Km2, has a population of 6,454 inhabitants, and is located on a coastal plain adjacent to the coastline. The whole plain is affected by episodes of coastal flooding and the regional climate cycle is mainly determined by the latitudinal migration of the Intertropical Convergence Zone -ZCIT, the Northeast Trade Winds and the
Materials and methods
The flooding elevation or total sea level at the coast (TSL), which vary for each time (six hourly frequency, 0, 6, 12, 12 UTC), was obtained as the sum of the contributing factors, as presented by several authors such as, Serafin and Ruggiero (2014), Villatoro et al. (2014), Melo et al. (2016), Melo et al. (2018), Hakkou et al. (2019), Serafin et al. (2017), Data et al. (2020), among others. For this approach, the TSL is estimated as follows.Where is the altimetry derived
Time series analysis
The six hourly data series of the variables contributing to the Total Sea Level (TSL) for the period 1993–2015 are shown in Fig. 8. The results show that the sea level anomaly series (SLA; Fig. 8a), astronomical tide series (AT; Fig. 8b) and storm surge (SS, Fig. 8c - gray lines) present values between −0.08 and 0.22 m, −0.19 m–0.29 m and 0.1 m–0.23 m, respectively. The mean and standard deviations are 0.04 m and 0.05 for SLA, 0 and 0.1 m for AT and 0 and 0.02 m for SS respectively. This agrees
Conclusions
In order to generate information to support decision-making in local planning, the variability in total sea level (TSL) on the coast of Moñitos, Córdoba, was analyzed. The significance of the different associated processes that cause variations on different time scales was also investigated. To achieve this, the total sea level (TSL) was modeled for the time window 1993 to 2015. The main findings are as follows:
In mean conditions, total sea level (TSL) in Moñitos has a semi-annual cycle with
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References (155)
- et al.
The impact of sea level rise on storm surge water levels in the northern part of the German Bight
Coast Eng.
(2015) - et al.
Wave energy potential assessment in the Caribbean Low Level Jet using wave hindcast information
Appl. Energy
(2015) - et al.
Coastal flooding hazard related to storms and coastal evolution in Valdelagrana spit (Cadiz Bay Natural Park, SW Spain)
Continent. Shelf Res.
(2006) - et al.
Occurrence of energetic extreme oceanic events in the Colombian Caribbean coasts and some approaches to assess their impact on ecosystems
J. Mar. Syst.
(2016) - et al.
How frequent is storm-induced flooding in the central part of the Bay of Biscay?
Global Planet. Change
(2014) - et al.
High resolution downscaled ocean waves (DOW) reanalysis in coastal areas
Coast Eng.
(2013) - et al.
Seasonal and nodal variations of predominant tidal constituents in the global ocean
Continent. Shelf Res.
(2021) - et al.
CMIP5-based global waveclimate projections including the entire Arctic Ocean
Ocean Model.
(2018) - et al.
Wave modelling in coastal and inner seas
Prog. Oceanogr.
(2018) - et al.
Effect of sea level rise on nearshore significant waves and coastal structures
Ocean. Eng.
(2016)