ABSTRACT

This study examined the role of extreme rainfall events in gully erosion formation at Umuhute/Umuaroko-Ahiaeke, Umuahia North Local Government Area, Abia State. The specific objectives were; to identify major causes of soil erosion in the study area, to identify extreme rainfall events in the study area over a period of 5 years and to evaluate the effects of extreme rainfall events on soil erosion. The study is developed via a descriptive research design. Data on daily rainfall for a period of 5 years were collected from the archive of the Nigerian Meteorological Agency (NIMET) and extreme rainfall events were extracted. Furthermore, a questionnaire survey was also carried out to generate first-hand information from residents whom had lived more than 5years in the area and not less than 23 years of age at time of distribution. The student T-test was used to compare extreme rainfall events and to test the following hypothesis: There is no significant difference in rainfall events over the past 5years (2013 – 2017) in the study area. Results showed that, rainfall, topography and type of soil were the major causes of gully erosion in the study area. Results also indicated that annual extreme rainfall totals amounted to 873.7 mm, 681.2 mm, 783.3 mm, 1123.7 mm and 818 mm for from 2013, 2014, 2015, 2016 and 2017 respectively. The wettest year is the year 2016 with an annual extreme rainfall amount of 1123.7 mm and with 16 extreme rainfall events. The two observed gullies have a 9% and 17% gradient with a sandy loamy textural class. Student T-test also revealed that, there is statistically significant difference in extreme rainfall events over the past 5years (2013-2017) at P<0.05 (F=4.5). It could therefore be stated that as a result of extreme rainfall events, the rate of gully formation increases. This situation can be exacerbated by climate change which has been reported to be increasing the frequency of exteme rainfall events. The study recommends that vegetation should be encouraged to curtail the impact of raindrops, especially the extreme rainfall type on soil.