ABSTRACT

This study determined the status and variations in the characteristics of the watershed along the River course traversing three communities in Isingwu Umuahia, Abia State, Nigeria. This study assessed the socio-economic activities, the floristic diversity of the watershed, watershed cover change over 30 years period, physicochemical properties of the soil, and water quality of the watershed health in the three surrounding communities of Umuda, Amafor and Umumgbokwo of Isingwu Umuahia, Abia State. Primary and secondary data were collected for this study. Copies of sixty (60) questionnaires were administered to respondents to determine socio-economic changes, vegetation, soil, and water assessment were carried out to ascertain changes in the watershed. The data obtained from Landsat Thematic Maps (TM) captured between 1989 and 2019 from the United States Geological Survey (USGS) was used to estimate land cover. The findings reveal that the people of Umuda, Amafor, and Umumgbokwo communities no longer derive as much of such services as fetching portable water from the river (98.3%), gathering firewood for sale from the wild (72%), fishing (54.4%) and swimming (92.3%) as they did before which was reported to be very severe in Umuda Isingwu community. The occurrence, composition, and density of trees, shrubs, herbs, climbers, grasses, and fern species were observed to be higher in the wet and dry seasons in the watershed of Umuda, Amafor, and Umumgbokwo communities. The Deforestation was higher in Umumgbokwo (83%) than other communities. There were significant higher number of individual species and total number of species, diversity, relative species abundance, and species richness of trees, shrubs, herbs, lianas, climbers, vines, grasses, and ferns in the three communities between the first and second year transect surveys at P ≤ 0.05, as well as between the wet and dry seasons at P ≤ 0.05. Farmland, barren soil, and undisturbed land declined in coverage area, while built-up areas have expanded. The water expanse in the study area significantly reduced by 59.35%, 15.68%, and 8.13% respectively over time in the three communities studied.  Significant differences were also found in the physicochemical parameters of the soil and water between the first and second year transect surveys at P ≤ 0.05, as well as between the wet and dry seasons at P ≤ 0.05 in the three communities. Water parameters, including temperature, total dissolved solids (TDS), pH, salinity, total hardness, potassium (K), calcium (Ca), magnesium (Mg), chemical oxygen demand (COD), chlorine (Cl₂) were found to be within the recommended permissible limits by the World Health Organization (WHO) except turbidity which was observed not to be within the limit in the three locations. The study revealed that watershed cover and physicochemical parameters of soil and water quality within the study communities were adversely affected by anthropogenic activities. The study recommends strict monitoring of the watershed, orientation of the locals, and involvement of the people in the watershed restoration program as measures to reduce deforestation and promote sustainable land management practices in the study sites to mitigate the negative impact on plant species composition and ecosystem services.