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Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa. WATER 2020. [DOI: 10.3390/w12092613] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although the Congo Basin is still one of the least studied river basins in the world, this paper attempts to provide a multidisciplinary but non-exhaustive synthesis on the general hydrology of the Congo River by highlighting some points of interest and some particular results obtained over a century of surveys and scientific studies. The Congo River is especially marked by its hydrological regularity only interrupted by the wet decade of 1960, which is its major anomaly over nearly 120 years of daily observations. Its interannual flow is 40,500 m3 s−1. This great flow regularity should not hide important spatial variations. As an example, we can cite the Ubangi basin, which is the most northern and the most affected by a reduction in flow, which has been a cause for concern since 1970 and constitutes a serious hindrance for river navigation. With regard to material fluxes, nearly 88 × 106 tonnes of material are exported annually from the Congo Basin to the Atlantic Ocean, composed of 33.6 × 106 tonnes of TSS, 38.1 × 106 tonnes of TDS and 16.2 × 106 tonnes of DOC. In this ancient flat basin, the absence of mountains chains and the extent of its coverage by dense rainforest explains that chemical weathering (10.6 t km−2 year−1 of TDS) slightly predominates physical erosion (9.3 t km−2 year−1 of TSS), followed by organic production (4.5 t km−2 year−1 of DOC). As the interannual mean discharges are similar, it can be assumed that these interannual averages of material fluxes, calculated over the longest period (2006–2017) of monthly monitoring of its sedimentology and bio-physical-chemistry, are therefore representative of the flow record available since 1902 (with the exception of the wet decade of 1960). Spatial heterogeneity within the Congo Basin has made it possible to establish an original hydrological classification of right bank tributaries, which takes into account vegetation cover and lithology to explain their hydrological regimes. Those of the Batéké plateau present a hydroclimatic paradox with hydrological regimes that are among the most stable on the planet, but also with some of the most pristine waters as a result of the intense drainage of an immense sandy-sandstone aquifer. This aquifer contributes to the regularity of the Congo River flows, as does the buffer role of the mysterious “Cuvette Centrale”. As the study of this last one sector can only be done indirectly, this paper presents its first hydrological regime calculated by inter-gauging station water balance. Without neglecting the indispensable in situ work, the contributions of remote sensing and numerical modelling should be increasingly used to try to circumvent the dramatic lack of field data that persists in this basin.
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Temporal Variability of Sediments, Dissolved Solids and Dissolved Organic Matter Fluxes in the Congo River at Brazzaville/Kinshasa. GEOSCIENCES 2020. [DOI: 10.3390/geosciences10090341] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
For three decades, the solid and dissolved fluxes of the Congo River have been regularly monitored on a monthly basis, despite 12 years of deficiencies (1994–2005). Two programs successively carried out these follow-ups: PEGI/GBF (1987–1993) and SO HYBAM (2006–2017), upstream and downstream, respectively, of the Malebo Pool near Brazzaville, the main hydrometric station of the Congo River. The objective of this study is to examine the temporal dynamic of TSS, TDS and DOC, to explore how these descriptors change over time. Comparison with the two time programs will shed more light on how these descriptors are related to discharge. Afterward, we then find a relationship between total TSS in the water column and that measured in surface for eventual estimation of TSS by remote sensing. In the last decade, compared to the PEGI/GBF period, the discharge of the Congo River was mainly marked by a 4% increase, leading to a significant change on TDS and DOC behaviors. The TSS was quite stable (from 8.2 and 9.3 t km−2 yr−1) due to the low physical erosion well known in this region. The TDS concentrations decreased slightly, by a simple dilution effect. However, the mineral dissolved fluxes (from 11.6 and 10.1 t km-2 yr-1) due to the chemical weathering and atmospheric inputs still predominate over the solid fluxes. Therefore, there was no radical change in the monthly geochemical regime of Congo River Basin (CRB) during these last 30 years. Contrariwise, the DOC concentration marking the biogeochemical processes significantly increased, from 9.0+/−3.0 mg L−1 to 12.7+/−5.0 mg L−1, due to more flooding events in the central part of the CRB. The change for the DOC fluxes is more relevant, with an increase of 45% between the two studied periods, from 11.1 × 106 to 16.2 × 106 t yr−1. This highlights the continuous and actual importance of the “Cuvette Centrale” in the heart of the CRB for dissolved organic matter transport by the Congo River.
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Zhang J, Huang WW, Liu MG, Zhou Q. Drainage basin weathering and major element transport of two large Chinese rivers (Huanghe and Changjiang). ACTA ACUST UNITED AC 1990. [DOI: 10.1029/jc095ic08p13277] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Nolting R, Hutagalung H, Moelyadi Moelyo D. Distribution of dissolved and particulate minor and major elements in the river and coastal environment of East Java during the Snellius-II expedition. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0077-7579(89)90023-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Sarin MM, Krishnaswami S. Major ion chemistry of the Ganga–Brahmaputra river systems, India. Nature 1984. [DOI: 10.1038/312538a0] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Martin JM, Thomas A, van Grieken R. Trace element composition of Zaire suspended sediments. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0077-7579(78)90043-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Eisma D, van Bennekom A. The Zaire river and estuary and the Zaire outflow in the Atlantic Ocean. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0077-7579(78)90030-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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