Hydrological Reanalysis for the Congo River Basin (1983-2020)

The Congo River basin (CRB), the world's second-largest river system, is subject to extreme hydrological events that strongly impact its ecosystems and population. Here we present an unprecedented 38-year (1983-2020) hydrological reanalysis of CRB daily discharge that helped us to analyze the spatiotemporal dynamics of recent major CRB floods and droughts, and their teleconnection with El Niño Southern Oscillation (ENSO), the dominant driver of tropical precipitation.

To develp this dataset, we employ a large-scale hydrologic-hydrodynamic model (MGB) with lake storage dynamics representation and a data assimilation (DA) technique using in-situ discharge and water level and remote sensing observations from radar altimetry.

The performance of MGB is satisfactory, with KGE indices of 0.84 and 0.71 for calibration and validation, respectively. Incorporating lake representation significantly improves the simulations, from 0.3 to 0.63 for the Pearson correlation coefficient. Furthermore, DA shows a ~13% reduction in simulated discharge errors through cross-validation.

This final version of the product uses all in-situ and radar altimetry observations during the simulation period, after satisfactory performance was verified in the DA cross-validation process. The original simulation period was from 1981 but the first two years were removed to avoid inconsistencies due to model initial conditions.