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1. Courbes de tarage du fleuve Congo à Brazzaville-Kinshasa

Author

Alain Laraque, Jérôme Le Coz, Guy Dieudonne Moukandi N’kaya, Grace Bissemo, Levy Ayissou, Nathalie Rouché, Jean-Pierre Bricquet, Santiago Yepez, and Georges Gulemvuga

Subjects
Hydrologie, courbe de tarage, fleuve Congo, incertitudes, ADCP, Hydrology, Hydraulic engineering, TC1-978, Environmental technology. Sanitary engineering, TD1-1066
Abstract

Les stations hydrométriques de Brazzaville et Kinshasa contrôlent 98% du bassin versant du Congo. Elles se situent à la sortie d’un bassin de tranquillisation pour mesurer les hauteurs d’eau et juste en amont d’un déversoir stable et sensible pour contrôler la relation hauteur-débit. Grâce à l’équivalence entre les deux jeux d’échelles, une longue série de référence a été reconstituée à partir de relevés limnimétriques quotidiens depuis 1902. De plus, 154 jaugeages ont été recensés dont 139 au moulinet pour les périodes 1955–1962 et 1971–1981 et 15 autres à l’ADCP depuis 2010. Ils couvrent tout le cycle hydrologique comme les principales phases d’écoulement ainsi que la quasi-totalité du marnage observé depuis 120 ans. Ce travail permet d’une part d’évaluer la stabilité de la section de contrôle grâce aux jaugeages Doppler, initiés 30 ans après la fin de ceux au moulinet et d’autre part, il permet la construction des courbes de tarage hauteur-débit avec estimation de l’incertitude, en combinant la connaissance a priori sur les contrôles hydrauliques et le contenu d’information des jaugeages incertains via la méthode bayésienne BaRatin. Une première estimation de la vitesse du fond mobile du fleuve Congo entre Brazzaville et Kinshasa est présentée.

Published
2022
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2. Recent Budget of Hydroclimatology and Hydrosedimentology of the Congo River in Central Africa

Author

Alain Laraque, Guy D. Moukandi N’kaya, Didier Orange, Raphael Tshimanga, Jean Marie Tshitenge, Gil Mahé, Cyriaque R. Nguimalet, Mark A. Trigg, Santiago Yepez, and Georges Gulemvuga

Subjects
hydroclimatology, hydrosedimentology, hydrogeochemical, Congo River Basin, Hydraulic engineering, TC1-978, Water supply for domestic and industrial purposes, TD201-500
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.

Published
2020
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9. Suivi hydrologique par altimétrie spatiale dans le bassin du Congo

Author

Blaise Léandre Tondo, Pierre-Olivier Malaterre, Georges Gulemvuga Guzanga, Christophe Brachet, Sébastien Legrand, and Alice Andral

Subjects
Environmental sciences, QE1-996.5, Environmental science, GE1-350, Geology, General Medicine
Abstract

Le satellite SWOT sera lancé fin 2022 par le Centre National d'Etudes Spatiales (CNES) français et la National Aeronautics and Space Administration (NASA) américaine. L'altimétrie spatiale permet de compléter les données hydrométriques in situ à travers l'établissement de «stations virtuelles», au croisement de la trace au sol du satellite avec un cours d'eau. SWOT améliorera encore la couverture des zones observées ainsi que la précision grâce à une technologie innovante. Un projet d'appui à la Commission Internationale du bassin Congo-Oubangui-Sangha (CICOS) développé depuis 2016 sur financement de l'Agence Française de Développement (AFD) et facilité par l'Office International de l'Eau (OiEau) permet de promouvoir l'hydrologie spatiale à travers un groupe d'institutions françaises, en appui à la CICOS. Diverses activités ont été développées dont la fourniture d'une base de données spatiales par l'Institut de Recherche pour le Développement (IRD), ainsi que la comparaison avec des données in situ. Une méthodologie innovante a été proposée par l'Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE) pour passer des altitudes aux débits aux stations virtuelles. Des applications spécifiques ont par ailleurs été développées par la Compagnie Nationale du Rhône (CNR) pour l'hydroélectricité et la navigation fluviale.

Published
2021

10. River discharge estimation from satellite observations. Application in the Congo river basin

Author

Pierre Olivier Malaterre, Christophe Brachet, Georges Gulemvuga Guzanga, Blaise Leandre Tondo, Alice Andral, David Dorchies, and Mathias Chouet

Abstract

Spatial altimetry allows to complete in-situ hydrometric data through the establishment of "virtual stations", at the crossing of the satellite ground track with a watercourse. Elevation measurements of water bodies and rivers are available on the Hydroweb-NG website (http://hydroweb.theia-land.fr). The SWOT satellite, scheduled for launch mid november 2022 by the French Centre National d'Etudes Spatiales (CNES) and the U.S. National Aeronautics and Space Administration (NASA), should further improve accuracy, thanks to innovative technology. Other types of multi-sensor space data are also useful in hydrology. A project to support the International Commission of the Congo-Ubangi-Sangha river basin (CICOS) developed since 2016 with funding from the French Development Agency (AFD) has promoted space hydrology through a group of French institutions supporting CICOS. Various activities have been developed including the development of a spatial database, comparison with in-situ data and the development of an operational Hydrological Information System within CICOS, integrating both spatial and in-situ data.In the framework of the Space Hydrology Group and the CICOS support project, an innovative methodology has been developed to estimate flows from currently available satellite data (Envisat, Jason, Sentinel, etc.), transforming altitudes into flows at virtual stations. These satellite data can be complemented by global databases (width databases with GWD-LR or Sword, mean flow databases with WBM, or Digital Terrain Model databases with SRTM Mission), as well as in-situ data on the studied area (2 hydrological stations in Kinshasa East on the Congo and Bangui on the Ubangi river). This methodology, tested on these 2 rivers, allowed the generation of a hydraulic model of the Saint-Venant 1D type, allowing the generation of Q(Z) calibration curves at any point of the river. Powered by satellite altimetry data, these calibration curves provide flow rates. A web-based interface has been developed providing this information in real-time. The comparision of the bathymetry obtained with this method with ADCP measurements, the analysis of the rating curve at two in-situ stations, and the time delay of the hydraulic model, proved to be very satisfactory, having into consideration all the hypothesis made in this methodology.

Published
2022

13. A global agenda for advancing freshwater biodiversity research

Author

Ralf B. Schäfer, Matthew Gollock, Hans Jürgen Hahn, Pierre A. Mvogo Ndongo, Jason D. Stockwell, Zeb S. Hogan, Jonathan M. Jeschke, Francis S. Magbanua, Thibault Datry, Clifford A. Ochs, Javier Muzon, Shin-ichiro S. Matsuzaki, James H. Thorp, Benjamin Kupilas, Martin Friedrichs-Manthey, Jens C. Nejstgaard, Harmony Patricio, Janne Soininen, Nike Sommerwerk, Susanne Worischka, Rita Adrian, Juergen Geist, Jan J. Kuiper, Angelica Batista-Morales, Ismael A. Kimirei, Levan Mumladze, David Dudgeon, Mathias Kuemmerlen, Meilan Jiang, Christopher P. Gordon, Georges Gulemvuga, Peter Haase, Astrid Schmidt-Kloiber, Jean Ricardo Simões Vitule, Ding Wang, Jonathan D. Tonkin, Topiltzin Contreras-MacBeath, Gregor Kalinkat, Sami Domisch, Hans-Peter Grossart, Virgilio Hermoso, Daniel Hering, Bert Kohlmann, Simone D. Langhans, Peter Goethals, Donald J. Baird, Qinghua Cai, Richard K. Johnson, Claudio Baigún, Alain Maasri, Subodh Sharma, Mireia Valle, Jeffrey J. Opperman, Jana Friedrich, Florian Leese, Viola Clausnitzer, Steffen U. Pauls, Bindiya Rashni, Oxana Nikitina, Frank Suhling, Jani Heino, Joerg Freyhof, Rajeev Raghavan, Ole Seehausen, Pablo E. Gutiérrez-Fonseca, Alonso Ramírez, Tibor Eros, Klaus-Douwe B. Dijkstra, Lee E. Brown, Steven J. Cooke, Vere Ross-Gillespie, Aventino Kasangaki, Gonzalo Delacámara, Michael T. Monaghan, Richard Lansdown, Fengzhi He, Bakhtiyor Karimov, Christian Wolter, Luc De Meester, Oghenekaro Nelson Odume, Michael J. Samways, Deep Narayan Shah, Franz Hölker, Klement Tockner, Mark O. Gessner, Martin Volk, Rebecca Tharme, Ram Devi Tachamo Shah, Núria Bonada, David Tickner, Van Tu Do, João Vitor Campos-Silva, Mihai Adamescu, Charles P. Hawkins, Hendrik Freitag, Sonja C. Jähnig, Institute of Biotechnology, Biosciences, Department of Geosciences and Geography, Helsinki Institute of Sustainability Science (HELSUS), Thrall, Peter (Herausgeber*in), and Thrall, Peter

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Research areas, data infrastructure, freshwater biodiversity crisis, Social ecology, Biodiversity, Fresh Water, bepress|Life Sciences|Biodiversity, 010501 environmental sciences, 01 natural sciences, CITIZEN SCIENCE, bepress|Life Sciences, freshwaters, Research priorities, Freshwaters, CHALLENGES, Ecology, QS Ecology, Management, research priorities, 1181 Ecology, evolutionary biology, Data infrastructure, Life Sciences & Biomedicine, Biologie, management, Conservation of Natural Resources, Monitoring, Evolution, Ecology (disciplines), Environmental Sciences & Ecology, 010603 evolutionary biology, GeneralLiterature_MISCELLANEOUS, Freshwater biodiversity crisis, Behavior and Systematics, Political science, 14. Life underwater, Environmental planning, DAMS, Ecosystem, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Science & Technology, 010604 marine biology & hydrobiology, 15. Life on land, social ecology, monitoring, 13. Climate action, Sustainable management, Earth and Environmental Sciences, 570 Life sciences, biology, Stewardship
Abstract

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation. ispartof: ECOLOGY LETTERS vol:25 issue:2 pages:255-263 ispartof: location:England status: published

Published
2022

14. Cover Image

Author

Alain Maasri, Sonja C. Jähnig, Mihai C. Adamescu, Rita Adrian, Claudio Baigun, Donald J. Baird, Angelica Batista‐Morales, Núria Bonada, Lee E. Brown, Qinghua Cai, Joao V. Campos‐Silva, Viola Clausnitzer, Topiltzin Contreras‐MacBeath, Steven J. Cooke, Thibault Datry, Gonzalo Delacámara, Luc De Meester, Klaus‐Douwe B. Dijkstra, Van Tu Do, Sami Domisch, David Dudgeon, Tibor Erös, Hendrik Freitag, Joerg Freyhof, Jana Friedrich, Martin Friedrichs‐Manthey, Juergen Geist, Mark O. Gessner, Peter Goethals, Matthew Gollock, Christopher Gordon, Hans‐Peter Grossart, Georges Gulemvuga, Pablo E. Gutiérrez‐Fonseca, Peter Haase, Daniel Hering, Hans Jürgen Hahn, Charles P. Hawkins, Fengzhi He, Jani Heino, Virgilio Hermoso, Zeb Hogan, Franz Hölker, Jonathan M. Jeschke, Meilan Jiang, Richard K. Johnson, Gregor Kalinkat, Bakhtiyor K. Karimov, Aventino Kasangaki, Ismael A. Kimirei, Bert Kohlmann, Mathias Kuemmerlen, Jan J. Kuiper, Benjamin Kupilas, Simone D. Langhans, Richard Lansdown, Florian Leese, Francis S. Magbanua, Shin‐ichiro S. Matsuzaki, Michael T. Monaghan, Levan Mumladze, Javier Muzon, Pierre A. Mvogo Ndongo, Jens C. Nejstgaard, Oxana Nikitina, Clifford Ochs, Oghenekaro Nelson Odume, Jeffrey J. Opperman, Harmony Patricio, Steffen U. Pauls, Rajeev Raghavan, Alonso Ramírez, Bindiya Rashni, Vere Ross‐Gillespie, Michael J. Samways, Ralf B. Schäfer, Astrid Schmidt‐Kloiber, Ole Seehausen, Deep Narayan Shah, Subodh Sharma, Janne Soininen, Nike Sommerwerk, Jason D. Stockwell, Frank Suhling, Ram Devi Tachamo Shah, Rebecca E. Tharme, James H. Thorp, David Tickner, Klement Tockner, Jonathan D. Tonkin, Mireia Valle, Jean Vitule, Martin Volk, Ding Wang, Christian Wolter, and Susanne Worischka

Subjects
Ecology, Evolution, Behavior and Systematics
Published
2022

15. Progress in Integrated Water Resources Management implementation

Author

Georges Gulemvuga, Zambia, Mahendra Mehta, Julie Ladel, and Lemmy Namayanga Eaudyssey

Subjects
Water resources, Sustainable development, Operationalization, business.industry, Integrated water resources management, media_common.cataloged_instance, Commission, European union, business, Environmental planning, Hydropower, Devolution, media_common
Abstract

Integrated Water Resources Management (IWRW) has made significant strides since its definition following the Rio Conference on Sustainable Development. Part of Sustainable Development Goal 6, the implementation of IWRM is foreseen globally by 2030. Initially, planning water resources in an integrated manner was the focus of most projects/programmes; hence, nowadays most of the efforts are targeted towards its implementation with practical implications for the nations and their populations.Successful achievements on this agenda are shared as well as challenges and possible way forward. Experiences from India, DRC and Zambia will be particularly presented and discussed. In Rajasthan (India), the devolution of IWRM was attempted at large scale from the State government to the communities. Approximatively 3,200 groups of villages (Gram Panchayat) were targeted and their integrated local plans prepared. The Congo Basin International Commission (CICOS) developed several tools for better managing this key transboundary basin of the Congo river. Spatial altimetry was largely developed throughout the basin and provides several operational applications such as for navigation services and hydropower potential characterization. In Zambia, the Water Resources Management Authority (WARMA) has established four catchment offices in four of its six catchments to better manage, develop, conserve and protect water resources.The article concludes on the progress made by transboundary organizations and countries of two continents (Africa and Asia) towards operationalization and implementation of IWRM. It analyses the achievements, benefits and lessons learnt and concludes on the way forward to attain SDG6 by 2030.

Published
2019

17. Suivi des variables hydrologiques par télédétection et modélisation dans le bassin du fleuve Congo

Author

Paris, Adrien, primary, Calmant, Stéphane, additional, Gosset, Marielle, additional, Fleischmann, Ayan S., additional, Conchy, Tainá Sampaio Xavier, additional, Garambois, Pierre‐André, additional, Bricquet, Jean‐Pierre, additional, Papa, Fabrice, additional, Tshimanga, Raphael M., additional, Guzanga, Georges Gulemvuga, additional, Siqueira, Vinícius Alencar, additional, Tondo, Blaise‐Leandre, additional, Paiva, Rodrigo, additional, Silva, Joecila Santos, additional, and Laraque, Alain, additional

Published
2022
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19. Monitoring Hydrological Variables from Remote Sensing and Modeling in the Congo River Basin

Author

Paris, Adrien, primary, Calmant, Stéphane, additional, Gosset, Marielle, additional, Fleischmann, Ayan S., additional, Conchy, Taina Sampaio Xavier, additional, Garambois, Pierre‐André, additional, Bricquet, Jean‐Pierre, additional, Papa, Fabrice, additional, Tshimanga, Raphael M., additional, Guzanga, Georges Gulemvuga, additional, Siqueira, Vinícius Alencar, additional, Tondo, Blaise‐Leandre, additional, Paiva, Rodrigo, additional, Silva, Joecila Santos, additional, and Laraque, Alain, additional

Published
2022
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22. Author response for 'A global agenda for advancing freshwater biodiversity research'

Author

null Alain Maasri, null Sonja C. Jähnig, null Mihai C. Adamescu, null Rita Adrian, null Claudio Baigun, null Donald J. Baird, null Angelica Batista‐Morales, null Núria Bonada, null Lee E. Brown, null Qinghua Cai, null Joao V. Campos‐Silva, null Viola Clausnitzer, null Topiltzin Contreras‐MacBeath, null Steven J. Cooke, null Thibault Datry, null Gonzalo Delacámara, null Luc De Meester, null Klaus‐Douwe B. Dijkstra, null Van Tu Do, null Sami Domisch, null David Dudgeon, null Tibor Erös, null Hendrik Freitag, null Joerg Freyhof, null Jana Friedrich, null Martin Friedrichs‐Manthey, null Juergen Geist, null Mark O. Gessner, null Peter Goethals, null Matthew Gollock, null Christopher Gordon, null Hans‐Peter Grossart, null Georges Gulemvuga, null Pablo E. Gutiérrez‐Fonseca, null Peter Haase, null Daniel Hering, null Hans Jürgen Hahn, null Charles P. Hawkins, null Fengzhi He, null Jani Heino, null Virgilio Hermoso, null Zeb Hogan, null Franz Hölker, null Jonathan M. Jeschke, null Meilan Jiang, null Richard K. Johnson, null Gregor Kalinkat, null Bakhtiyor K. Karimov, null Aventino Kasangaki, null Ismael A. Kimirei, null Bert Kohlmann, null Mathias Kuemmerlen, null Jan J. Kuiper, null Benjamin Kupilas, null Simone D. Langhans, null Richard Lansdown, null Florian Leese, null Francis S. Magbanua, null Shin‐ichiro S. Matsuzaki, null Michael T. Monaghan, null Levan Mumladze, null Javier Muzon, null Pierre A. Mvogo Ndongo, null Jens C. Nejstgaard, null Oxana Nikitina, null Clifford Ochs, null Oghenekaro Nelson Odume, null Jeffrey J. Opperman, null Harmony Patricio, null Steffen U. Pauls, null Rajeev Raghavan, null Alonso Ramírez, null Bindiya Rashni, null Vere Ross‐Gillespie, null Michael J. Samways, null Ralf B. Schäfer, null Astrid Schmidt‐Kloiber, null Ole Seehausen, null Deep Narayan Shah, null Subodh Sharma, null Janne Soininen, null Nike Sommerwerk, null Jason D. Stockwell, null Frank Suhling, null Ram Devi Tachamo Shah, null Rebecca E. Tharme, null James H. Thorp, null David Tickner, null Klement Tockner, null Jonathan D. Tonkin, null Mireia Valle, null Jean Vitule, null Martin Volk, null Ding Wang, null Christian Wolter, and null Susanne Worischka

Published
2021

23. A new look at hydrology in the Congo Basin, based on the study of multi-decadal chronicles

Author

Jean-Emmanuel Paturel, Guy Dieudonne Moukandi N’Kaya, Gil Mahé, Raphael Tshimanga, Georges Gulemvuga, and Alain Laraque

Subjects
Hydrology (agriculture), Work (electrical), Homogeneous, Streamflow, Physical geography, Structural basin, Geology
Abstract

The latest work on the main African rivers on the Atlantic coast has made it possible to subdivide the multi-year streamflow records into several homogeneous phases. The year 1970 seems to mark bot...

Published
2020

24. Recent budget of hydroclimatology and hydrosedimentology of the Congo River in Central Africa

Author

Santiago Yepez, Gil Mahé, Georges Gulemvuga, Raphael Tshimanga, Guy Dieudonne Moukandi N’Kaya, C.R. Nguimalet, Didier Orange, Jean Marie Tshitenge, Mark A. Trigg, Alain Laraque, Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), University Marien Ngouabi of Brazzaville (umng), Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), University of Kinshasa (UNIKIN), Hydrosciences Montpellier (HSM), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Bangui, University of Leeds, Universidad de Concepción [Chile], Commission Internationale du Bassin Congo-Oubangui-Sangha (CICOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Universidad de Concepción - University of Concepcion [Chile]

Subjects
lcsh:Hydraulic engineering, 010504 meteorology & atmospheric sciences, Geography, Planning and Development, 0207 environmental engineering, Drainage basin, Aquifer, 02 engineering and technology, Aquatic Science, Structural basin, 01 natural sciences, Biochemistry, Water balance, Hydrology (agriculture), lcsh:Water supply for domestic and industrial purposes, lcsh:TC1-978, Tributary, hydroclimatology, hydrosedimentology, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, 020701 environmental engineering, hydrogeochemical, 0105 earth and related environmental sciences, Water Science and Technology, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, lcsh:TD201-500, geography.geographical_feature_category, Plateau, 15. Life on land, 6. Clean water, 13. Climate action, Erosion, Environmental science, Congo River Basin, Physical geography
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.

Published
2020

25. Determination of the Correlation between the Air Temperature Measured in Situ and Remotely Sensed Data from MODIS and SEVIRI in Congo-Brazzaville

Author

Maixent Olivier C. Kambi, Zhenhui Wang, and Georges Gulemvuga

Subjects
In situ, Spectroradiometer, Remote sensing (archaeology), Climate change, Environmental science, Spatial variability, Satellite imagery, Satellite, General Medicine, Moderate-resolution imaging spectroradiometer, Remote sensing
Abstract

This study compared data from the MODerate-resolution Imaging Spectroradiometer (MODIS) onboard NASA’s Terra satellite and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on EUMETSAT’s Meterosat Second Generation (MSG) satellite with in situ data obtained from ground observation stations in Congo-Brazzaville. Remote sensing instruments can be used to estimate air temperature, which has an important role in monitoring the effects of climate change. Congo-Brazzaville is located in equatorial forest, which is difficult to access, and has a limited number of ground meteorological stations measuring air temperature. This study used MODIS and MSG data for the period 2009-2014 to assess the performance of land surface temperature data from satellites against in situ data from ground-based stations in Congo-Brazzaville using a linear regression model. This work has allowed us to determine which satellite is best adapted for use in Central Africa.

Published
2018

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