Assessment of impacts of land use, land cover on water quality in Eleyele catchment area, Ibadan, south-western Nigeria

In recent times, land cover is primarily altered by human activities, such as agriculture, livestock farming, forest harvesting and management, and urban and suburban construction and development. As at the time of this study, no prior study has reported the changes in land use and land cover (LULC) in the Eleyele catchment area of Ibadan using conventional or digital remote sensing data and GIS. This study therefore investigated the impacts of LULC on water quality within the Eleyele catchment in Ibadan, Oyo State, Nigeria. This was assessed via temperature, pH, EC, TS, TDS, TSS, calcium hardness, total hardness, magnesium hardness, calcium, magnesium, phosphorus, chloride, BOD, potassium, sodium, ammonium, acidity, turbidity, and total bacterial count in relation to agricultural, industrial, urban, and domestic practices. Using Geographic Information Systems and Landsat TM imagery from 1984 and 2019 (both at 35 m resolution), a supervised classification was applied. The results indicate that the total area of the newly delineated Eleyele catchment map for all LULC classes in 2019 was 290.98 km2. Agriculture covered 196.92 km2 in 1984 and 172.5 km2 in 2019, while forest areas covered 231.88 km2 in 1984 and 85.69 km2 in 2019. Urban areas expanded from 16.26 km2 in 1984 to 183.87 km2 in 2019, and the water body increased from 5.90 km2 in 1984 to 8.82 km2 in 2019. Urbanization, industrial activities emerged as the primary drivers of water quality degradation corresponding with LULC change between 1984 and 2019. These findings underscore the need for continuous monitoring of LULC effects on the catchment. The authors recommend that relevant authorities develop and enforce policies aimed at protecting water quality and maintaining ecosystem health. Strategies suggested include reforestation, afforestation, implementation of green infrastructure, and wetland protection and restoration.