J.O Ehiorobo

Flooding remains one of the most pressing environmental challenges in the Niger Delta region of Nigeria, where rapid urbanization, land degradation, and climate variability interact to intensify hydrological extremes. This study evaluates the combined impact of land use/land cover (LULC) changes and climate variability on flooding in the Lower Niger Region, focusing on Edo, Delta, Bayelsa, and Rivers States. An integrated methodological framework was developed using remote sensing (RS) and machine learning (ML) techniques implemented on the Google Earth Engine (GEE) platform. Rainfall and temperature datasets were obtained from multiple satellite products, CHIRPS, PERSIANN-CDR, PERSIANN-CCS, ERA5, and CPC, and validated against observations from the Nigerian Meteorological Agency (NiMET). LULC classification was conducted using Random Forest (RF) and Support Vector Machine (SVM) algorithms applied to Sentinel-2 and Landsat-8 imagery, generating five major land cover classes: water bodies, forest, barren land, vegetation, and built-up areas. Flood dynamics were assessed using multiple spectral indices, including AWEI, FWI, NDWI, MNDWI, WRI, and NDVI, evaluated across different temporal scales to capture hydrological variations. The results reveal significant interannual and seasonal rainfall variability, with the Standardized Precipitation Index (SPI) effectively identifying alternating wet and dry cycles, although long-term annual rainfall trends were largely non-significant. There is, however, evidence of increasing frequency of extreme rainfall events, particularly in Delta and Rivers States. Temperature analysis (1971–2023) indicates a statistically significant warming trend, with minimum temperatures rising faster than maximum temperatures—most notably during the dry season (DJF). LULC assessment confirmed the superior performance of the RF classifier over SVM and showed a consistent pattern of urban expansion at the expense of vegetation and wetlands. Flood analysis revealed a persistent hotspot occurring along river corridors, low-lying floodplains, and southeastern basins. Overall, the findings demonstrate that while climate variability influences hydrological extremes, LULC transformations, particularly urban encroachment into natural flood buffers, have been a more decisive factor driving flood vulnerability in the Lower Niger Region.