The 1970 Congo River Basin drought: early warning signals and climate recovery revealed by a Bayesian-based approach

Transient processes (TP) in the Congo River Basin (CRB) have received little attention. This study uses the concept of a climate disturbance signal (CDS) to characterize the TP that led to the 1970 drought in the CRB. The CDS was derived from posterior probabilities obtained through a Bayesian approach of gridded precipitation data. Its persistence quantified using Kendall and Moran spatial auto-correlations showed a gradual rise to a peak in 1971, followed by a decline until 1977. This evolution highlights two key insights: the 1970 drought was preceded by more than a decade of early warning signals, and the basin’s climate required nearly 7 years to reach equilibrium. These findings emphasize the crucial role of the TP in hydroclimatology and demonstrate the practical value of the CDS for water management, hydraulic planning, and climate risk mitigation. Furthermore, this study reduces the uncertainty in the spatio-temporal representativeness of the CRB climate.