Assessment of Slope Dynamics and Land Use Impact on Groundwater Recharge and Flood Risks: a case study of Bayelsa State, Niger Delta

The Niger Delta region of Nigeria, characterized by low-gradient terrain, significantly influences groundwater dynamics and flood risks. This study focuses on the Kolokuma/Opokuma, Ogbia, and Yenagoa areas in Bayelsa State to assess the implications of slope variations and land use on these hydrological processes. Geographic Information System (GIS) techniques were utilized to analyze slope degrees, slope length and steepness factors, and Land Use and Land Cover (LULC) types across the study region. Slope analysis determined the distribution of slope degrees and steepness factors, while LULC analysis identified the dominant land cover types and their influence on hydrological processes. Slope analysis revealed that approximately 38.5% of the study area has a slope degree of 0 - 1.67°, indicating predominantly flat terrain. The steepness analysis showed that 94.5% of the area falls within the lowest category of steepness factors (0.00 - 6.77). LULC analysis highlighted that tree cover dominates (1625.45 km²), promoting groundwater recharge, while built-up areas (127.96 km²) contribute to increased flood risks. The findings emphasize the vulnerability of the region to flooding due to low-gradient slopes and significant built-up areas that reduce infiltration. The dominance of tree cover benefits groundwater recharge, but urban impermeable surfaces exacerbate flood risks, particularly in Yenagoa. This study underscores the need for integrated land use and flood management strategies in Bayelsa State to balance groundwater recharge with flood mitigation, highlighting the importance of preserving natural land cover for hydrological stability.