ASSESSMENT OF RAINFALL EROSIVITY IN AWKA, NIGERIA USING THE MODIFIED FOURNIER INDEX

C.P. Nwachukwu, L.C. Orakwe, E.C. Nwanna, K.N. Ogbu

Abstract


Erosion is one of the major environmental problems in the world, especially in the Southeastern part of Nigeria. This has affected agriculture and other activities involving the use of land. Excessive rainfall which results in peak runoff causes detachments which leads to erosion. In soil erosion modeling, especially using the Universal Soil Loss Equation (USLE), rainfall erosivity (R) factor is an important factor, as this defines the aggressivity of rainfall. Rainfall erosivity is the ability of rainfall to detach soil particles. The modified Fournier Index (MFI) is a widely used method to estimate rainfall erosivity, which is a measure of the potential of rainfall to cause erosion. For this study, a rainfall data of 21 years (2003-2023) for Awka, Anambra State was collected from Nigerian Meteorological Agency (NIMET). The Modified Fournier Index (MFI) was used to determine the rainfall erosivity in this study because of the availability of rainfall data. The MFI values were determined from monthly and yearly rainfall data. From the obtained monthly MFI, lower values were obtained in dry season, while higher values were in rainy season, with highest MFI value of 216.87 in September 2018. The yearly MFI ranges from 204.44 to 556.5. From test of significance at p<0.05, a significant p value of 0.03 was obtained, which shows that that the grouped data are similar. The result shows that the aggressivity of rainfall is high in the area and this can result in removal and detachment of soil particles and this may lead to erosion. This study helps to understand rainfall patterns and intensity and this can provide insights into the impacts of climate change on soil erosion and water resources for the study area. By estimating rainfall erosivity, researchers can identify areas prone to soil erosion and provide valuable information.

KEYWORDS: Modified Fournier index, Universal soil loss equation, rainfall erosivity, aggressivity, detachment


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References


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