Ogooué basin

The ogooué river is the second largest river in term of discharge in Central Africa after the Congo river and its basin is located between 9° and 15° E, and 3°S and 2.5° N.

 

Water levels and discharges (1995-2017) of the Ogooué river basin were estimated using radar altimetry data from the the following missions: Jason-2 (2008-2016), Jason-3 (since 02/2016), ERS-2 (1996-2003), ENVISAT (2002-2010), SARAL (2013-2016), Sentinel-3A (since 02/2016) and Cryosat-2 (since 2010), but also from the second (drifting) orbit of ENVISAT (2010-2012). These data were made available by Centre de Topographie des Océans et de l’Hydrosphère (CTOH). In this study, an altimetry-based network of 34 virtual stations (VS) was defined across the Ogooué river and its major tributaries (Ivindo and Ngounie) and the Multi-mission altimetry Processing Software (MAPS) was used for processing altimetry data based on the method detailed in (Frappart et al., 2015). Combination of datasets from several VS to infer long term time series of water level and discharge at Lambaréné was made based on the method described in (Papa et al., 2012).

Ogooué Basin Virtual Station Ogooué
Figure 1: Locations of the altimetry virtual stations in the Ogooué River Basin. VS from ERS-2, ENVISAT, ENVISAT 2nd orbit, SARAL, Sentinel-3A, Cryosat-2, Jason-1, Jason-2, Jason-3 are represented using orange stars, white stars, brown dots, red dots, blue squares, cyan triangles, green squares and orange diamonds respectively. For readability purpose, virtual stations from missions with repeat period shorter than 35 days are presented in a) and virtual stations from Cryosat-2 are presented in b).

 Figure 2: Time series of water level at Lambaréné from the in-situ gauge record (black continuous line), the multi-mission altimetry-based record (ERS-2 data are represented with diamonds, ENVISAT with blue crosses on its nominal orbit and with green triangles on its second orbit, Cryosat-2 with green-blue stars, SARAL with red circles, Sentinel-3 with purple dots)

 

Reference

Bogning, S.; Frappart, F.; Blarel, F.; Niño, F.; Mahé, G.; Bricquet, J. P.; Seyler, F.; Onguéné, R.; Etamé, J.; Paiz, M. C.; Braun, J. J. Monitoring water levels and discharges using radar altimetry in an ungauged river basin: the case of the Ogooué. Submitted.             
Home — CTOH Available online: http://ctoh.legos.obs-mip.fr/ (accessed on Oct 24, 2017).

Cited references:

Frappart, F.; Papa, F.; Marieu, V.; Malbeteau, Y.; Jordy, F.; Calmant, S.; Durand, F.; Bala, S. Preliminary Assessment of SARAL/AltiKa Observations over the Ganges-Brahmaputra and Irrawaddy Rivers. Mar. Geod. 2015, 38, doi:10.1080/01490419.2014.990591.
             
Papa, F.; Bala, S. K.; Pandey, R. K.; Durand, F.; Gopalakrishna, V. V.; Rahman, A.; Rossow, W. B. 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. J. Geophys. Res. Ocean. 2012, 117, n/a-n/a, doi:10.1029/2012JC008158.

Data access:

This dataset will be soon available on Hydroweb (http://hydroweb.theia-land.fr/). Before, you can contact Sakaros Bogning (sakaros.bogning@legos.obs-mip.fr) and Frédéric Frappart (frederic.frappart@legos.obs-mip.fr).

 

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