Effects of Land Use Land Cover Run Off on Surface Water Quality in Enugu Urban Area, Enugu State, Nigeria

Abstract

The physico-chemical characteristic of runoff on land use land cover along the river basin  as well as geographical dispositions, combined with anthropogenic factors are strong causative factors of of  pollution in surface water quality in the study area. The purpose of this research determines the effect of land use land cover along the river basin on surface water quality in Enugu urban area. The landsat 8 of 2017 of Enugu urban was downloaded from United State Geological Survey (USGS) web site and was used to assess the land use land cover of the study area through remotely sensing pixel based image classification. The measurements were conducted on the on six major rivers in the study area (Ekulu, Asata, Aria, Idaw, Ayo and Ogbete river). Two samples were collected from each river but Ekulu river being the longest of all, three samples were collected with aid of handheld Geographical Position System (GPS).  The laboratory test was conducted on the sample water to assess the physico-chemical characteristic of surface water in the study area. All the generated data was imported into ArcGIS software where the Geostatistical analysis was run.  The physico-chemical parametes were analysed using Inverse Distance Weighting (IDW) interpolation. Inverse distance weighted (IDW) interpolation explicitly implements the assumption that things that are close to one another are more alike than those that are farther apart. GIS proximity analysis was used to determine the river basin by creating a buffer of 500 m along the main river line and 250m along the tributary.  The result shown that the total percentage covered by residential land use (urban land) area is 35.19%, followed by woodland (32.09%) and then  tropical rain  forest(12.16%) the agricultural area accounted for 2.22%. above that the urban area is mostly caused the degradation of urban waterways. The runoff water with high concentration of physico-properties was recorded in urban area. The major pollutants found in runoff from urban areas include Ph, Total Dissolved Solid, Temperature, Conductivity and turbidity. It also revealed that urban area and vegetation area were the most highly pollutants land use in the study area because of its high concentration of chemical-properties. the nature of the quality of surface water from runoff in various land use in the study area using remote sensing image classification  shows that the land use land cover of the area has been drastically affected by physico-chemical properties of surface water runoff and this is evidently clear from land use land cover Maps of  Enugu urban Subcatchment area. Additional studies should be conducted to cover the rural areas of Enugu state for land use and cover analysis, for extraction runoff /land degradation prone area in order to educate and evacuate inhabitants of the environs before runoff lead land failure occurs.

Keywords: Land Use, Land Cover, Runoff, Water Quality, Surface Water.