Water and Sediment Budget of Casiquiare Channel Linking Orinoco and Amazon Catchments, Venezuela

Abstract

The Casiquiare River is a natural channel that connects two of the greatest rivers in the world, the Orinoco and the Amazon in the South American continent. The aim of this paper is to present a review and synthesis of the hydrological and sedimentological knowledge of the Casiquiare River, including the first hydro-sedimentary balance of the Casiquiare fluvial system conducted 9–12 September 2000 at the bifurcation and mouth during the expedition ‘Humboldt-Amazonia 2000’. Bathymetric flow discharge and physico-chemical measurements were made at the inlet and outlet of the Casiquiare Channel. The main conclusions of this study indicate that Casiquiare is taking a significant proportion of flow (20% to 30%) from the Upper Orinoco basin to the Amazon basin. Throughout its 356 km-course, this chameleon channel undergoes significant morphological, hydrological, and bio-geochemical variations between the inlet and outlet, whose most visible witnesses are the increase in its width (3 to 4 times), flow (7 to 9 times), and its change in water color (white to black water), under the influence of tributaries coming from vast forest plains.

Special Issue “Multiscale Impacts of Anthropogenic and Climate Changes on Tropical and Mediterranean Hydrology”

“…This Special Issue presents results of studies from many different parts of the world, mainly from Africa and Europe, including the Mediterranean area, Asia [11,12], and South America [13]. The papers showcase studies under equatorial, tropical humid, semi-arid, and Mediterranean climate.…”

“…The papers showcase studies under equatorial, tropical humid, semi-arid, and Mediterranean climate. All spatial scales are investigated, from the very local scale of gullies in Spain [14] to the largest rivers of the world, the Amazon and Orinoco rivers in South America [13] and Congo River in Central Africa [15]. The whole African continent is also the topic of the paper of Dieulin et al [16] (2020), presenting a new continental monthly rainfall dataset at the half-degree square scale covering the years 1940 to 1999, computed only from observations from ground-based stations.…”

“…The topics studied cover a large panel of hydrological questions. Many of them deal with the study of time series variability, rainfall [16], discharges [19,20], sediment transport [11][12][13]21], recession coefficient [22,23], climate change impacts [17,24], or anthropogenic impacts [2,11,20,21]. Drought is also a topic of notable interest in Mediterranean and tropical areas [23][24][25].…”

“…Laraque et al [13,15] also deal with very large scales, as they cover the three largest rivers of the world by discharge value, all located in equatorial-tropical areas, the Amazon and Orinoco rivers in South America and Congo River in Central Africa. These papers highlight low-documented areas.…”

“…These papers highlight low-documented areas. In South America, the study is focused on the very curious and much unknown Casiquiare Canal, linking both the giant Orinoco and Amazon rivers, investigated during a dedicated international expedition in 2000 [13]. The results presented for the Congo River cover more than one century of measurements and represent the most recently documented synthesis on the Congo River water, with an investigation of dissolved and suspended matters fluxes [15].…”