El Niño driven extreme sea levels in an Eastern Pacific tropical river delta: Landward amplification and shift from oceanic to fluvial forcing
Belliard, J.-P.; Dominguez-Granda, L.E.; Ramos-Veliz, J.A.; Rosado-Moncayo, A.M.; Nath, J.; Govers, G.; Gourgue, O.; Temmerman, S. (2021). El Niño driven extreme sea levels in an Eastern Pacific tropical river delta: Landward amplification and shift from oceanic to fluvial forcing. Global Planet. Change 203: 103529. https://dx.doi.org/10.1016/j.gloplacha.2021.103529 In: Global and Planetary Change. Elsevier: Amsterdam; New York; Oxford; Tokyo. ISSN 0921-8181; e-ISSN 1872-6364, more |  |
| Keywords | Marine/Coastal; Fresh water | | Author keywords | ENSO; Extreme sea levels; River delta; Flood risks; Coastal ecosystems; Coastal societies |
| Authors | | Top | - Belliard, J.-P., more
- Dominguez-Granda, L.E.
- Ramos-Veliz, J.A.
- Rosado-Moncayo, A.M.
| - Nath, J.
- Govers, G., more
- Gourgue, O., more
- Temmerman, S., more
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| Abstract | As greenhouse warming is predicted to intensify the El Niño–Southern Oscillation (ENSO), it is key to understand relationships between the magnitudes and spatial distribution of ENSO events and associated extreme sea levels (ESLs). Current understanding is lacking for river deltas, where human societies and ecosystems are particularly vulnerable to coastal hazards. Using long-term tide gauge records, we report on ESLs during historical ENSO events of different magnitudes, spatial distribution and temporal evolution in the Guayas delta–Gulf of Guayaquil (Ecuador), the largest estuarine system on the Pacific coast of South America and a relevant hotspot for coastal hazards. Here, we found a landward amplification of sea level anomalies during Eastern Pacific El Niño events, with monthly mean values peaking from +43 cm at the open coast to +75 cm in the inner delta, producing among the highest ENSO driven ESLs ever documented. This landward amplification is shown to coincide with a sea-to-land gradient from a predominantly oceanic (thermosteric) to meteorological (fluvial) El Niño contribution to these ESLs, demonstrating the strong coupling between these two forcings of El Niño. Our findings highlight the strong exposure of coastal societies and ecosystems to ENSO driven ESLs and the pressing need for adaptation measures in face of continued global warming. |
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