Understanding the influence of climate variability on surface water
hydrology in the Congo basin
Abstract
Understanding the impacts of climate on surface water hydrology is
required to predict consequences and implications on freshwater
habitats, ecological assets, and wetland functions. Although the Congo
basin is considerably a freshwater-rich region, largely characterised by
numerous water resources after the similitude of the Amazon basin,
recent accounts of droughts in the basin are indications that even the
most humid regions of the world can be affected by droughts and its
impacts. Given the scarcity and limited availability of hydrological
data in the region, GRACE (Gravity Recovery and Climate Experiment)
observations are combined with model and SPEI (standardized
precipitation evapotranspiration index) data to investigate the
likelihood of such impacts on the Congo basin’s surface water hydrology.
By integrating multivariate analysis with support vector machine
regression (SVMR), this study provides some highlights on the
characteristics (intensity and variability) of drought events and
GRACE-derived terrestrial water storage (TWS) and the influence of
global climate on the Congo river discharge. The southern section of the
basin shows considerable variability in the spatial and temporal
patterns of SPEI and extreme droughts over the Congo basin appear to
have persisted with more than 40% coverage in 1994. However, there has
been a considerable fall in drought intensities since 2007 and coincides
with periods of strong positive anomalies in discharge (i.e., 2007-010).
GRACE-derived TWS over the Congo basin is driven by annual fluctuations
in rainfall (r = 0.81 at three months phase lag) and strong inter-annual
variations of river discharge (r = 0.88, α= 0.05). Generally, results
show that changes in the surface water variations (from gauge and model
output) of the Congo basin is a key component of the GRACE water column.
The outputs of the SVMR scheme indicate that global climate through sea
surface temperature anomalies of the Atlantic (r = 0.79, α= 0.05),
Pacific (r = 0.79, α= 0.05), and Indian (r = 0.74, α= 0.05) oceans are
associated with fluctuations in the Congo river discharge, and confirm
the importance of climatic influence on surface water hydrology in the
Congo basin.