Assessment of Rainfall Variability and Its Impact on Soil Erosion Risk Using Rainfall Erosivity in Kwara
Year: 2026
Type: article
Abstract: Rainfall is the primary driver of water-induced soil erosion, and its erosive power is quantified by rainfall erosivity. Rainfall in Kwara state, Nigeria is believed to be the major cause of erosion. Hence, this study assessed the spatio-temporal distribution of rainfall and rainfall erosivity in Kwara State, Nigeria, for the period 2000 to 2025, with the aim was of determining the pattern of rainfall, the pattern of its erosive power, and the linkage between both parameters to soil erosion and soil conservation planning. Rainfall data and Rainfall Erosivity maps for six epochs, 2000, 2005, 2010, 2015, 2020 and 2025, were acquired and analyzed using geospatial techniques. Nine sample points (S1-S9) were extracted across the state to quantify trends. The Rainfall Erosivity (R-Factor) in RUSLE was used to measure the power of rainfall to cause soil erosion. Trend analysis, scatter plot and linear regression were used to establish the relationship between rainfall (RNF) and erosivity (ER). Results revealed a consistent northwest to southeast gradient for both parameters. The northern LGAs of Baruten, Kaiama and Patigi consistently recorded Very Low to Low rainfall and Low erosivity, with values as low as 566.33 MJ mm ha-1 h-1 yr-1 in 2000, while the southern LGAs of Ekiti, Oke-Ero, Isin, Ifelodun, Irepodun and Offa consistently recorded High to Very High rainfall and High erosivity, peaking at 1277.56 MJ mm ha-1 h-1 yr-1 in 2010. Temporally, both parameters peaked in 2010, with state average rainfall of 1819.57 mm and average erosivity of 1014.47, and were lowest in 2000. A perfect positive linear relationship was established with the equation ER = 0.562 x RNF -8.1, proving that rainfall directly controls erosion risk. The study also revealed a baseline shift, where the minimum erosivity in 2025 (693.7) was higher than the maximum in 2000 (749.05), indicating increasing rainfall intensity. The study concludes that Kwara State is becoming more erosive and that southern Kwara is the erosion hotspot requiring urgent conservation measures.
Source: HAL
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7221755863