Geospatial Analysis of Wetlands Degradation in Makurdi, Nigeria

Abstract

Aims: The study aims to identify wetlands from different study epochs using remote sensing images and also detect any changes in their extent or existence; correlate changes with nearby land use and land cover over time; identify wetland losses within the stipulated epochs; and, also project future levels of degradation (up to 2026) based on the trend observed between 1996 and 2016. Place and Duration of Study: The study area covers Makurdi LGA in Benue State, Nigeria. The study focused between the periods 1996 through 2016 to 2026. Methodology: To estimate the land use/cover change in Makurdi, Landsat ETM, ETM+ and OLI satellite data for 1996, 2006 and 2016, were respectively utilised. The study adapted the Kappa index for assessing the accuracy of the land use/cover maps generated from the analysis to improve the efficiency of results. An accuracy level of 80 to 91% was achieved. The land consumption rate (LCR) and land absorption coefficient (LAC) were applied to establish the role population increase plays in the rate of land consumption over specific spatio-temporal scales. Results: The results reveal an overall significant increase in built-up area and other land uses at the expense of wetlands from 26.3% in 1996 to 18.1% in 2016. Further analysis includes the land consumption rate (LCR) and land absorption coefficient (LAC) which reveals the role of population expansion in the recorded levels of wetland losses recorded in this study. The study projects a further decline of wetland cover by 33.15 km2 (or by 22.57%) in 2026 if steps are not instituted to control the current rate of decline.  Conclusion: Given the findings and limitations of the study, some critical suggestions are made for further studies in line with the red list index (RLI) and to align with and incorporate into policy the strategic need to adopt the provisions of the SDGs (especially goal 15) at the level of Makurdi.