Urbanisation Effects on Surface and Groundwater Resources: An Assessment of Approved Dumpsite in Ibadan, Nigeria

Abstract. Ajakanga dumpsite, Ibadan is an open dumpsite operated by Oyo State government with an area of 10.034ha. Forested dumpsite area which was opened in 1996 and still in operation till date with a current land use pattern of built up urban settlement. The study was designed to assess groundwater qualities from existing hand-dug wells and surface water qualities from a stream bordering the existing dumpsite for its suitability for domestic and agricultural water use. Four hand-dug wells were chosen as sampling points for groundwater while two sampling points were selected for surface water analysis. All these were located within a radius of 200m from the dumpsite. Samples were collected weekly over a period of six months during the rainy season when leachates from the dumpsite are at the highest possibility of contaminating surface and groundwater resources. The water samples were analysed for physico-chemical quality parameters and heavy metals. Analyzed parameters such as pH, temperature, turbidity, COD, DO, Cl^-, NO₃^-, SO₄^2-, PO₄^3- and Cr⁺⁺ falls within the standard permissible limits of WHO and NESREA. However, parameters such as Fe⁺⁺, Mn⁺⁺⁺, and Zn⁺⁺ with mean values 0.54mg/L, 0.07mg/L and 0.48mg/L were above permissible limits by NESREA for irrigation or agricultural water use while TDS and conductivity with mean values of 779.33mg/L and 913.11 μS were above permissible limits by WHO for drinking water. Operation of open dumpsites in Ibadan, Nigeria which is typical of many developing countries in sub-Saharan Africa without proper waste sorting into degradable and non-degradable wastes can lead to environmental hazards as a result of water contamination arising from urbanization needs urgent attention. Control of non-degradable wastes ending up in open dumpsites in developing countries requires urgent attention with appropriate technology (engineered dumpsite) for environmentally friendly waste management practices for solid waste disposal operated to accepted world standards.