Assessing Orinoco river sediment discharge trend using MODIS satellite images. (April 2019)

• Record Type: Journal Article
• Authors: Gallay, Marjorie; Martinez, Jean-Michel; Mora, Abrahan; Castellano, Bartolo; Yépez, Santiago; Cochonneau, Gérard; Alfonso, Juan A.; Carrera, Juan Manuel; López, José Luis; Laraque, Alain
• Is Part Of: Journal of South American earth sciences. Volume 91(2019)
• Page Start: 320
• Page End: 331
• Publication Date: 2019-04
• Subjects: MODIS -- Suspended sediments -- Sediment load -- Orinoco river -- Water color; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2019.01.010
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The aim of this study was to derive the Surface Suspended Sediment Concentration (SSSC) and river sediment discharge (for the period 2000-2016) along the Orinoco River reaches using MODIS remote sensing data. A single SSC retrieval algorithm was calibrated using HYBAM long term monitoring program data (n = 183). The comparison of satellite and field measurements showed a RMSE of 32%, corresponding to a mean absolute error of 21 mg l −1 . These results supported the use of MODIS sensors to monitor the SSSC at six virtual stations in the middle and lower reaches of the Orinoco River. The highest mean SSSC were found downstream of the Meta River (101 mg l −1 ) and of the Apure River (99 mg l −1 ), which provide the major sediment input to the Orinoco main stream. The lowest mean SSSC was found upstream of the Meta River (42 mg l −1 ). In the lower reach, at Ciudad Bolivar station we assessed a mean SSSC of 88 mg l −1 . MODIS-derived and ground-derived assessments of the annual sediment discharge show very fine agreement, within −2%. Coupling satellite-derived SSSC estimates and river discharge monitoring data, we calculated the Orinoco River sediment discharge at Ciudad Bolivar station between 2001 and 2016. For a mean Orinoco River discharge of 33, 320 m 3 .s −1, the sediment loads varied from 75 to 103 Mt.yr −1, with a mean value of 89 Mt.yr −1 (RSD of 9%) corresponding to a sediment yield of 91–125 t.km −2 yr −1 with no positive or negative trends over the observed period. Highlights: The Orinoco River surface suspended sediment concentration (SSSC) was estimated using MODIS sensors. The results shown a general increasing trend in SSSC with, however, spatial and temporal variations. The suspended sediments loads and yields have shown no significant change over the observed period. These results are of particular interest in the context of increasing or decreasing trends observed in most South American rivers.