Impact of sea-level rise on coastal marshes of the Lower Paraná River and the Río de la Plata Estuary

C VILLAR,; VAITHIYANATHAN P,; BONETTO, C.

Current Topics in Wetland Biogeochemistry

Año: 1999 vol. 3 p. 182 - 193

Abstract. Humans have intensively impacted the Río de la Plata basin. Deforestation followed by intense agriculture and damming is the greatest modification within the Upper Paraná and Uruguay basins. Although erosion rates are large, damming has reduced the suspended matter load of the Upper Paraná and Uruguay Rivers. Since major suspended matter contribution to the middle Paraná comes from the Bermejo R., the sedimentary load was large enough to support the Paraná deltaic progradation until present. Macrophytes play a mayor role in deltaic marshes accretion because of high organic matter production and enhanced riverine particulate matter retention. Present vegetation has counterbalanced larger riverine water level rises in the last decades than future estimated sea level rises. Strong resilience of deltaic marshes suggests that future sea level rises will have little effect on them. Coastal marshes of the Río de la Plata seems more fragile. Plant growth and biomass are lower while inflorescences are developed earlier and at an increased rate than in the deltaic marshes in response to a more energetic environment. Until present the coast has been prograding in the inner estuary while erosion was dominant in the outer estuary. Sea level rise will cause the upstream migration of the salinity gradient increasing suspended matter availability and facilitating accretion. However storms will most probably cause extended coastal erosion and land loss.