Rainfall Pattern and its effects on sediment deposition in the Niger River Basin, Ajaokuta, Kogi State

Abstract

This study examined how changes in rainfall, surface water, and land use affect sediment movement and buildup along the Niger River near Ajaokuta, Kogi State, Nigeria. The research focused on understanding how climate changes and human activities together impact sediment deposition in the river.Rainfall data from NASA POWER for 1981 to 2024 were analyzed to find trends and variations. To track surface water changes, the Normalized Difference Water Index (NDWI) was calculated using Landsat satellite images from 2017 and 2024. These images were also used to classify land cover into vegetation, bare land, water, and sediment using a supervised classification method with Maximum Likelihood.Results showed the average yearly rainfall in Ajaokuta is about 2,000 mm but varies a lot from year to year. Between 2017 and 2024, dense vegetation dropped by 14%, while bare land and built-up areas rose by 10%, showing increased human impact. NDWI values ranged from 0.05 to 0.46, reflecting fluctuating water levels linked to dry and wet periods.Higher rainfall years caused more erosion and sediment to deposit on floodplains. The study found a clear connection between rainfall changes, loss of vegetation, and sediment patterns. It concludes that sediment buildup in this river section is mainly due to shifts in rainfall and land cover changes from human activities.The study recommends better vegetation management, planting more trees, and continuous monitoring using satellites to reduce erosion. It also suggests adaptive watershed management considering future rainfall changes to protect the river and its environment. This research shows how combining rainfall data, satellite images, and land use analysis helps us understand and manage sediment in tropical rivers like the Niger.