Changing precipitation regimes and implications for water insecurity in Nigeria using innovative trend and drought analyses

Climate change, particularly precipitation dynamics, has always been a major factor affecting water insecurity. In this study, the spatial and temporal dynamics of precipitation patterns and drought fluctuations were examined across Nigeria’s climate regions using long-term precipitation records (1981–2022). A novel integration of the Innovative Trend Analysis (ITA) and Standardised Precipitation and Precipitation-Evapotranspiration Indices (SPI and SPEI) was employed to investigate changes in annual and seasonal rainfall and compare the hydroclimatic conditions. The findings indicate significant spatial variability in precipitation patterns, resulting from the West African Monsoon and local climatic factors. The middle-belt (Abuja and Jalingo) had an overall drying trend (p-value < 0.05), whereas the arid north (Sokoto and Kukawa) was found to be wet and showed greater extremes of rainfall. Drought analysis revealed high temporal coherence between the SPI and SPEI, indicating that precipitation drives hydroclimatic variability, while evapotranspiration becomes a dominant factor in arid and transitional regions. The middle-belt had long dry intervals (SPEI < −2), while the arid and coastal regions had less frequent, albeit intense, wet episodes (SPEI > +2), especially on the long-term. These opposite hydroclimatic conditions point to the beginning of an unbalanced water cycle in Nigeria, where floods and drought become an increasing threat. The findings emphasize the significance of adaptive water management strategies, such as the implementation of drought-resistant crops and irrigation systems in the middle belt and enhanced floodwater harvesting plans in the north. Graphical Abstract