Sustainability of Mediterranean Deltaic and Lagoon Wetlands with Sea-Level Rise: The Importance of River Input

Abstract

We report on a decadal trend of accretionary dynamics in the wetlands of several northwestern Mediterranean deltas and a lagoon system, all of them with high rates of wetland loss. Wetland vertical accretion and surface elevation change were measured at 55 riverine, marine, and impounded sites in four coastal systems: the Ebro delta, Spain; the Rhône delta, France; and the Po delta and Venice Lagoon, Italy. Vertical accretion and elevation change ranged between 0 and 25 mm year −1 and were strongly correlated. The highest rates of elevation gain occurred at riverine sites where vertical accretion was highest. We conclude that areas with high sediment input, mainly riverine, are the only ones likely to survive accelerated sea-level rise, especially if recent higher estimates of 1 m or more in the twenty-first century prove to be accurate. This is the first study where the importance of river input on wetland survival has been demonstrated at a decadal time scale over a broad geographical area.

The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

“…Since many of the wetlands most susceptible to sea-level rise are deficient of mineral sediment (e.g. Kirwan et al, 2010;Day et al, 2011), we suggest that once the primary productivity of a marsh starts to decline, sustained and perhaps accelerated rates of decomposition will only exacerbate the syndrome through loss of elevation.…”

A global standard for monitoring coastal wetland vulnerability to accelerated sea-level rise

“…Crucially, however, previous studies have revealed high acrosssite variability in the processes that contribute to surface elevation change [32][33][34] , making assumptions of uniformity in processes across wetlands inappropriate. This highlights the need for site-specific data that accurately represent local processes to initialize, calibrate and validate site-specific wetland models, and to evaluate the outcome of different SLR scenarios 35,36 .…”

Sediment Deposition at the Caernarvon Crevasse during the Great Mississippi Flood of 1927: Implications for Coastal Restoration

“…These processes of floodplain and delta inundation and draining have built land along river corridors and in deltas around the world [38,46,[48][49][50][51]. Where levees have not stopped river floods, overbank flooding still occurs, such as in the Danube [52], northwestern Mediterranean deltas [53] and for the Atchafalaya delta of the Mississippi [48], and leads to more sustainable wetlands. There is a general consensus that major world deltas will become smaller in the 21st century due to accelerated sea-level rise and a reduction in sediment input (e.g., [54]).…”