ESTIMATING FLUVIAL DISCHARGE IN THE CARIBBEAN SEABOARD OF COLOMBIA: MAGNITUDE, VARIABILITY AND EXTREME EVENTS

Abstract

Monthly freshwater discharge data of ten rivers draining into the Caribbean Sea in the northern of Colombia (Caribbean alluvial plain) are analyzed. The data are used to quantify the magnitude, to estimate long-term trends, and to evaluate variability patterns of freshwater discharges into the ocean. These Colombian rivers contribute with ~340.9 km3 yr-1 of freshwater into the Caribbean Sea. The Magdalena River delivers the largest discharge, with a mean discharge at Calamar of 205.5 km3 yr-1 which represents 26% of the total fluvial discharge into this basin. From 2000 to 2010 the annual streamflow of these rivers rose up three fold. However, only the Mulatos, Canal del Dique, Magdalena, and Fundación Rivers have significant statistical upward trends. The concurrence of the major oscillation processes and the maximum power of the 3-7 year fluctuation defined a period of intense hydrological activity around 1998-2002. Wavelet spectrum analysis indicated a change in the variability patterns of fluvial systems between 2000 and 2010, characterized by a shift toward a domain of quasi-decadal processes (8-12 years). The Intertropical Convergence Zone (ITCZ), ENSO events, and quasi-decadal climate processes (e.g. sea surface temperatures over tropical North Atlantic, Pacific Decadal Oscillation) are the main factors controlling fluvial discharge variability of these fluvial systems.