Satellite-based estimates of surface water dynamics in the Congo River Basin

In the Congo River Basin (CRB), due to the lack of contemporary in situ observations, there is a limited understanding of the large-scale variability of its present-day hydrologic components and their link with climate. In this context, remote sensing observations provide a unique opportunity to better characterize those dynamics. Analyzing the Global Inundation Extent Multi-Satellite (GIEMS) time series, we first show that surface water extent (SWE) exhibits marked seasonal patterns, well distributed along the major rivers and their tributaries, and with two annual maxima located: i) in the lakes region of the Lwalaba sub-basin and ii) in the “Cuvette Centrale”, including Tumba and Mai-Ndombe Lakes. At an interannual time scale, we show that SWE variability is influenced by ENSO and the Indian Ocean dipole events. We then estimate water level maps and surface water storage (SWS) in floodplains, lakes, rivers and wetlands of the CRB, over the period 2003-2007, using a multi-satellite approach, which combines the GIEMS dataset with the water level measurements derived from the ENVISAT altimeter heights. The mean annual variation in SWS in the CRB is 81±24 km3 and contributes to 19±5 % of the annual variations of GRACE-derived terrestrial water storage (33±7 % in the Middle Congo). It represents also ~6±2 % of the annual water volume that flows from the Congo River into the Atlantic Ocean.

[1]  Evan Weller,et al.  Increased frequency of extreme Indian Ocean Dipole events due to greenhouse warming , 2014, Nature.

[2]  C. Birkett,et al.  Evaluation of JERS-1 SAR mosaics for hydrological applications in the Congo river basin , 2002 .

[3]  Yoann Malbéteau,et al.  Surface Freshwater Storage Variations in the Orinoco Floodplains Using Multi-Satellite Observations , 2014, Remote. Sens..

[4]  C. Birkett,et al.  The contribution of TOPEX/POSEIDON to the global monitoring of climatically sensitive lakes , 1995 .

[5]  Benguela Ninos,et al.  Interannual Variability in the , 2010 .

[6]  D. Lettenmaier,et al.  Measuring surface water from space , 2004 .

[7]  Jean-Pierre Bricquet,et al.  LES ECOULEMENTS DU CONGO A BRAZZAVILLE ET LA SPATIALISATION DES APPORTS , 1993 .

[8]  J. Janowiak,et al.  The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present) , 2003 .

[9]  G. Samba,et al.  Rainfall variability in Congo‐Brazzaville: 1932–2007 , 2012 .

[10]  A. Cazenave,et al.  Preliminary results of ENVISAT RA-2-derived water levels validation over the Amazon basin , 2006 .

[11]  Catherine Prigent,et al.  Wetland dynamics using a suite of satellite observations: A case study of application and evaluation for the Indian Subcontinent , 2006 .

[12]  J. Crétaux,et al.  Lake studies from satellite radar altimetry , 2006 .

[13]  F. Frappart,et al.  Combining high-resolution satellite images and altimetry to estimate the volume of small lakes , 2013 .

[14]  Charon Birkett,et al.  Indian Ocean Climate event brings floods to East Africa's lakes and the Sudd Marsh , 1999 .

[15]  F. Aires,et al.  Changes in land surface water dynamics since the 1990s and relation to population pressure , 2012 .

[16]  Frédérique Seyler,et al.  Water Level Fluctuations in the Congo Basin Derived from ENVISAT Satellite Altimetry , 2014, Remote. Sens..

[17]  Y. Hong,et al.  The TRMM Multisatellite Precipitation Analysis (TMPA): Quasi-Global, Multiyear, Combined-Sensor Precipitation Estimates at Fine Scales , 2007 .

[18]  Jean-Claude Olivry,et al.  Variations des précipitations et des écoulements en Afrique de l’Ouest et centrale de 1951 à 1989 , 1995 .

[19]  D. Alsdorf,et al.  Characterization of complex fluvial systems using remote sensing of spatial and temporal water level variations in the Amazon, Congo, and Brahmaputra Rivers , 2010 .

[20]  Hahn Chul Jung,et al.  Mapping wetland water depths over the central Congo Basin using PALSAR ScanSAR, Envisat altimetry, and MODIS VCF data , 2015 .

[21]  William B. Rossow,et al.  Ganga-Brahmaputra river discharge from Jason-2 radar altimetry: An update to the long-term satellite-derived estimates of continental freshwater forcing flux into the Bay of Bengal , 2012 .

[22]  Frédéric Frappart,et al.  Time variations of land water storage from an inversion of 2 years of GRACE geoids , 2005 .

[23]  J. Crétaux,et al.  Hydrology and Earth System Sciences Evaluation of the Isba-trip Continental Hydrologic System over the Niger Basin Using in Situ and Satellite Derived Datasets v. Pedinotti Et Al.: Isba-trip Continental Hydrologic System over the Niger Basin , 2022 .

[24]  Carina Gardiner.  Atlas Climatique du Bassin Congolais , 1971 .

[25]  Dah-Ning Yuan,et al.  The JPL RL05M GRACE Mascon Solution , 2017 .

[26]  F. O'Loughlin,et al.  Hydraulic characterization of the middle reach of the Congo River , 2013 .

[27]  C. Reason,et al.  Sensitivity of the southern African circulation to dipole sea‐surface temperature patterns in the south Indian Ocean , 2002 .

[28]  F. Achard,et al.  Determination of Deforestation Rates of the World's Humid Tropical Forests , 2002, Science.

[29]  A. Cazenave,et al.  Floodplain water storage in the Negro River basin estimated from microwave remote sensing of inundation area and water levels , 2005 .

[30]  Denis A. Hughes,et al.  Initial calibration of a semi-distributed rainfall runoff model for the Congo River basin , 2011 .

[31]  Javier Tomasella,et al.  Satellite-based estimates of groundwater storage variations in large drainage basins with extensive floodplains , 2011 .

[32]  C. Prigent,et al.  Remote Sensing of Global Wetland Dynamics , 2000 .

[33]  R.H. Spigel,et al.  Comparison of Hydrology and Physical Limnology of the East African Great Lakes: Tanganyika, Malawi, Victoria, Kivu and Turkana (with reference to some North American Great Lakes) , 2019, The Limnology, Climatology and Paleoclimatology of the East African Lakes.

[34]  F. Bryan,et al.  Time variability of the Earth's gravity field: Hydrological and oceanic effects and their possible detection using GRACE , 1998 .

[35]  Étienne Bernard.  Le climat écologique de la cuvette centrale congolaise , 1949 .

[36]  Frédéric Frappart,et al.  Variations of surface water extent and water storage in large river basins: A comparison of different global data sources , 2008 .

[37]  H. Douville,et al.  A new river flooding scheme for global climate applications: Off‐line evaluation over South America , 2008 .

[38]  Aaron Boone,et al.  The Hydrological Modeling and Analysis Platform (HyMAP): Evaluation in the Amazon Basin , 2012 .

[39]  Frédérique Seyler,et al.  Monitoring Continental Surface Waters by Satellite Altimetry , 2008 .

[40]  Filipe Aires,et al.  Toward a High-Resolution Monitoring of Continental Surface Water Extent and Dynamics, at Global Scale: from GIEMS (Global Inundation Extent from Multi-Satellites) to SWOT (Surface Water Ocean Topography) , 2016, Surveys in Geophysics.

[41]  Pierre Camberlin,et al.  Seasonality and atmospheric dynamics of the teleconnection between African rainfall and tropical sea‐surface temperature: Atlantic vs. ENSO , 2001 .

[42]  Shilong Piao,et al.  Modelling sub-grid wetland in the ORCHIDEE global land surface model: evaluation against river discharges and remotely sensed data , 2012 .

[43]  Catherine Prigent,et al.  An attempt to quantify the impact of changes in wetland extent on methane emissions on the seasonal and interannual time scales , 2010 .

[44]  M. Watkins,et al.  Improved methods for observing Earth's time variable mass distribution with GRACE using spherical cap mascons , 2015 .

[45]  J. Crétaux,et al.  Lake Volume Monitoring from Space , 2016, Surveys in Geophysics.

[46]  F. O'Loughlin,et al.  Opportunities for hydrologic research in the Congo Basin , 2016 .

[47]  J. B. Miller,et al.  Contribution of anthropogenic and natural sources to atmospheric methane variability , 2006, Nature.

[48]  Barry Smit,et al.  Climate Change and Forest Communities: Prospects for Building Institutional Adaptive Capacity in the Congo Basin Forests , 2014, AMBIO.

[49]  S. Calmant,et al.  Water levels in the Amazon basin derived from the ERS 2 and ENVISAT radar altimetry missions , 2010 .

[50]  James L. Davis,et al.  Land water storage within the Congo Basin inferred from GRACE satellite gravity data , 2006 .

[51]  H. Douville,et al.  Global off-line evaluation of the ISBA-TRIP flood model , 2012, Climate Dynamics.

[52]  Michael Durand,et al.  Comparing satellite derived precipitation datasets using the Hillslope River Routing (HRR) model in the Congo River Basin , 2011 .

[53]  J. Greet,et al.  Trends in global CO2 emissions: 2012 report , 2012 .

[54]  David P. Roy,et al.  Wetland mapping in the Congo Basin using optical and radar remotely sensed data and derived topographical indices , 2010 .

[55]  C. Prigent,et al.  Interannual variations of river water storage from a multiple satellite approach: A case study for the Rio Negro River basin , 2008 .

[56]  Filipe Aires,et al.  Remote sensing of global wetland dynamics with multiple satellite data sets , 2001 .

[57]  Nicolas Baghdadi,et al.  Mapping of Central Africa Forested Wetlands Using Remote Sensing , 2014, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[58]  J. Bricquet,et al.  A review of material transport by the Congo River and its tributaries , 2009 .

[59]  Hahn Chul Jung,et al.  Controls of Terrestrial Water Storage Changes Over the Central Congo Basin Determined by Integrating PALSAR ScanSAR, Envisat Altimetry, and GRACE Data , 2014 .

[60]  Muddu Sekhar,et al.  Satellite-derived surface and sub-surface water storage in the Ganges–Brahmaputra River Basin , 2015 .

[61]  T. N. Krishnamurti,et al.  Climate and Circulation of the Tropics , 1987 .

[62]  F. Aires,et al.  Global inundation dynamics inferred from multiple satellite observations, 1993–2000 , 2007 .

[63]  Sharon E. Nicholson,et al.  The relationship of rainfall variability in West Central Africa to sea‐surface temperature fluctuations , 2007 .

[64]  C. Prigent,et al.  Surface freshwater storage and dynamics in the Amazon basin during the 2005 exceptional drought , 2012 .

[65]  K. Edwards,et al.  The water resource in tropical Africa and its exploitation , 1983 .

[66]  Marisa Goulden,et al.  Rainfall variability in East Africa: implications for natural resources management and livelihoods , 2005, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[67]  M. Watkins,et al.  The gravity recovery and climate experiment: Mission overview and early results , 2004 .

[68]  P. Jones,et al.  Updated high‐resolution grids of monthly climatic observations – the CRU TS3.10 Dataset , 2014 .

[69]  D. Nganga,et al.  Rainfall and temperature variations over Congo-Brazzaville between 1950 and 1998 , 2008 .

[70]  B. Goswami,et al.  A dipole mode in the tropical Indian Ocean , 1999, Nature.

[71]  Gil Mahé,et al.  Spatiotemporal variations in hydrological regimes within Central Africa during the XXth century , 2001 .

[72]  G. Mahé,et al.  Assessment of freshwater yields to the ocean along the intertropical Atlantic coast of Africa (1951-1989) , 1999 .

[73]  M. England,et al.  What causes southeast Australia's worst droughts? , 2009 .

[74]  Denis A. Hughes,et al.  Climate change and impacts on the hydrology of the Congo Basin: The case of the northern sub-basins of the Oubangui and Sangha Rivers , 2012 .

[75]  Jean-François Crétaux,et al.  Lakes Studies from Satellite Altimetry , 2011 .

[76]  S. Hastenrath,et al.  Diagnosing the 2005 Drought in Equatorial East Africa , 2007 .

[77]  F. Aires,et al.  Interannual variability of surface water extent at the global scale, 1993–2004 , 2010 .

[78]  E. Odada,et al.  The Limnology, Climatology and Paleoclimatology of the East African Lakes , 2019 .

[79]  Fernando Niño,et al.  An ERS-2 altimetry reprocessing compatible with ENVISAT for long-term land and ice sheets studies , 2016 .

[80]  Jean-François Crétaux,et al.  Recent hydrological behavior of the East African great lakes region inferred from GRACE, satellite altimetry and rainfall observations , 2010 .

[81]  Frédéric Frappart,et al.  Preliminary Assessment of SARAL/AltiKa Observations over the Ganges-Brahmaputra and Irrawaddy Rivers , 2015 .

[82]  C. K. Shum,et al.  Characterization of terrestrial water dynamics in the Congo Basin using GRACE and satellite radar altimetry , 2011 .

[83]  L. P. Smith.  Hydrology of humid tropical regions , 1984 .

[84]  M. Watkins,et al.  Quantifying and reducing leakage errors in the JPL RL05M GRACE mascon solution , 2016 .

[85]  R. H. Hughes,et al.  A directory of African wetlands. , 1992 .

[86]  F. Aires,et al.  Surface freshwater storage and variability in the Amazon basin from multi‐satellite observations, 1993–2007 , 2013 .

[87]  Edward T. A. Mitchard,et al.  Age, extent and carbon storage of the central Congo Basin peatland complex , 2017, Nature.

[88]  Pierre Defourny,et al.  Mapping Congo Basin vegetation types from 300 m and 1 km multi-sensor time series for carbon stocks and forest areas estimation , 2012 .

[89]  Swadhin K. Behera,et al.  Subtropical SST dipole events in the southern Indian Ocean , 2001 .

[90]  J. Balek,et al.  Hydrology and Water Resources in Tropical Africa , 1977 .

[91]  Catherine Prigent,et al.  Interannual variations of the terrestrial water storage in the Lower Ob' Basin from a multisatellite approach , 2009 .

[92]  T. Wehr,et al.  Geophysical validation of envisat data products , 2001 .

[93]  Jonathan L. Bamber,et al.  Ice sheet altimeter processing scheme , 1994 .