Vertical Land Motion as a Driver of Coastline Changes on a Deltaic System in the Colombian Caribbean

Abstract

To face and properly mitigate coastal changes at a local level, it is necessary to recognize and characterize the specific processes affecting a coastline. Some of these processes are local (e.g., sediment starvation), while others are regional (e.g., relative sea-level change) or global (e.g., eustatic sea-level rise). Long tide gauge records help establish sea-level trends for a region that accounts for global (eustatic, steric) and regional (isostatic) sea-level changes. Local sea-level changes are also the product of vertical land motion (VLM), varying depending on tectonic, sedimentological, and anthropogenic factors. We investigate the role of coastal land subsidence in the present-day dynamics of an abandoned delta in the Colombian Caribbean. Satellite images and synthetic aperture radar acquisitions are used to assess decadal-scale coastline changes and subsidence rates for the period 2007–2021. We found that subsidence rates are highly variable alongshore. Local subsidence rates of up to −1.0 cm/yr correspond with an area of erosion rates of up to −15 m/yr, but coastal erosion also occurs in sectors where subsidence was not detected. The results highlight that local coastline changes are influenced by multiple, interacting drivers, including sand supply, coastline orientation and engineering structures, and that subsidence alone does not explain the high rates of coastal erosion along the study area. By the end of the century, ongoing coastal erosion rates of up to −25 m/yr, annual rates of subsidence of about −1 cm/yr, and current trends of global sea-level rise are expected to increase flooding levels and jeopardize the existence of the deltaic barrier island.

Investigation of Multi-Timescale Sea Level Variability near Jamaica in the Caribbean Using Satellite Altimetry Records

“…For example, there are relatively shallow areas around islands such as the Jamaica Ridge [34] versus the Cayman trench, which is beyond 7600 m deep, located in the north Caribbean [35]. There are no studies we are aware of that quantify the impact of vertical land motion on sea level in the wider Caribbean Basin [36]; however, some studies have indicated an impact of vertical land motion on relative sea level rise in the Colombia Caribbean area in the southern Caribbean basin [36,37].…”

Vertical land motion reconstruction unveils non-linear effects on relative sea level

“…Ongoing changes in the cryosphere and hydrosphere cause variations in the VLM rates in the order of mm/year [11], which must be taken into account when extrapolating VLM from observations. Several other processes like erosion [35], human-induced extraction of groundwater, oil and gas [13-15, 36, 37], sediment loading and compaction [38][39][40] and volcanism (see tide gauge record at Miyake Sima in Figure 1A) can also produce highly localized and non-linear VLM. As an example, human-induced subsidence caused a strong acceleration in RSL around 1960 in Manila and Bangkok, leading to an overall RSL change of 75 cm since the beginning of the records, a change about four times as high as the GMSL change.…”

The influence of vertical coastal land movement on relative sea level rise: a case study of Shanghai, China

“…The VLM includes subsidence or uplift, due to natural processes (e.g., Glacial Isostatic Adjustment (GIA), sediment compaction, and tectonics) and anthropogenic processes (e.g., groundwater extraction and land-use change) (Higgins, 2016;Minderhoud et al, 2016;Yuill et al, 2009). Land subsidence has been identi ed as the main pattern of VLM (Dokka, 2006;Gómez et al, 2021). Because of the rapid sediment compaction and deposit, coastal delta regions are experiencing a faster rate of land subsidence than global SLR (Minderhoud, 2019;Tessler et al, 2018).…”