Impact of land use and land cover change in the riparian forests of Okpokwu River in Otukpo Local Government Area, Benue State,Nigeria

Abstract

Impact of land use and land cover change in the riparian forests of Okpokwu River in Otukpo Local Government Area, Benue State was assessed to determine the extent and magnitude of change in land cover features over the period of 30 years. The study made use of mostly secondary data from pre-existing satellite imageries. Three multi-date Landsat satellite imageries: Thematic Mapper (TM) of 1994, 2004; Enhanced Thematic Mapper (ETM+) of 2014 and Operational Land Imager (OLI) of 2024 were obtained from the Earth explorer platform of United States Geological Surveys (USGS). Images were processed and a supervised classification was carried out using maximum likelihood classifier in Idrisi and ArcGIS 10.3. The classification produced six classes of Riparian Forest, Built up Areas, Bare Surface, Farmland, Grassland and water bodies. Trend analysis of LULCC in riparian forests of Okpokwu River in Otukpo LGA revealed
that forest declined from 23.03% in 1994 to 13.16% in 2024. Similarly grassland declined considerably from 52.90% in 1994 to 27.09% in 2024. On the other hand, built up area increased from 7.15% in 1994 to 13.84% in 2024. Bare surface increased from 4.38% in 1994 to 18.36 in 2024. Farmland increased from 12.33% in 1994 to 26.65 in 2024. Also water bodies increased from 0.21% in 1994 to 0.90% in 2024. The magnitude of land use and land cover change within the 30-year Period revealed that -28.87 sq. km of forest cover was lost, similarly grassland decreased by -75.51 sq.km, on the contrary Built up areas increased by 19.53 sq.km, additionally Bare surface increased by 40.83 sq.km, also Farmland increased by 41.82 sq.km while Water bodies increased by 2.03 sq.km. As built up areas, bare surface and farmlands increased, this resulted in decline/degradation of riparian forests and grassland linked to increase in population. Increase in water bodies was linked majorly to the construction of Otukpo Dam in Agwu forest/Otobi. Regular monitoring was recommended so that changes in LULC could be detected early particularly now that a Dam is been constructed at Otobi for adequate planning and to avert flooding and its effect.