ESTIMATION OF SURFACE SUSPENDED SEDIMENT CONCENTRATION IN THE MAGDALENA RIVER MOUTH (COLOMBIA) USING MODIS IMAGES

Código

PAP051

Autores

Ana Carolina Torregroza, Juan Camilo Restrepo Lopez, Jaime Escobar, Natalia Hoyos, Jorge Pierini

Tema

PROCESSOS HIDROSSEDIMENTOLÓGICOS E MORFOLÓGICOS: FLUVIAIS, LACUSTRES E COSTEIROS

Resumo

Traditional field methods usedto monitor river?s superficial physicochemical characteristics have limitations over large areas. Many studies have used remote sensing tomonitor surface suspended sedimentdistribution. The Magdalena River is the main contributor of freshwater and sediments to the Caribbean Sea. The fluvial inputs of the Magdalena River are 10,287 m3s-1at high flow rates and 4,068 m3s-1at low flow rates, and sediment transportationhas been considered one of the largest in the world (142x106ty-1of suspended sediments). Here we developeda regional algorithm to estimate the surface suspended sediment concentration in the Magdalena River mouth using MODIS images. We analyzedmonthlyaverage surface suspended sediment concentration data for the period2003-2017. Satellite images were calibrated with in situmeasurements of surfacesuspended sedimentconcentrations in the study area. Results confirm that surface suspended sediment concentrationsaremuch higher than data reported from previous studiescarried outin the area. Concentrations data range from 2000 to 5000 mgL-1in the Magdalena river, from 500 to3000 mgL-1in the estuary (Bocas de Ceniza) and ?200 mgL-1along the adjacent coastal zone (Caribbean Sea). During thedry season the highest surfacesediment concentrations were obtained in the river and in the estuary. For this time periodthe Magdalena River plumemoves from Bocas de Cenizas towards the south-west along the coast with the littoral drift. Our results emphasize the importance of movementof sediments from the Magdalena River to the Caribbean Sea.This is an important processin the biogeochemical functioning of estuarine systemsand evenmore in highly turbid estuaries, where there is a marked variability in the surface distribution of sediments.