URBANIZATION EFFECTS ON WETLAND ECOSYSTEM IN PARTS OF NIGER STATE, NIGERIA

Abstract

Wetland ecosystems provide multiple benefits to human settlements; nonetheless, they are seriously threatened due to lack of planning and human activities associated mainly with urban growth. An understanding of their functioning and status is crucial for their protection and conservation. The development and use of coastal areas have increased in recent decades, resulting in significant environmental changes. Thus, these areas have presented different population structures and growth patterns linked to global urbanization trends and demographic changes. The aim of this study is to compare wetland depletion and simulate future changes in parts of Niger State (Chanchaga-Minna, Landzun - Bida and Kontagora) wetlands. Four multi-date Landsat satellite imageries, TM of 1988, 1998, ETM+ 2008 and OLI 2018, were utilized to generate data and was used to analyze and monitor changes that have occurred over time and space. Land-use change modeller was utilized to model the land use and land cover and simulate future urban land use of wetland into 2030. The Normalized Difference Built-up Index (NDBI) was adopted to extract built up features with indices ranging from -1 to 1. Also, simulation was performed by integrating three drivers (DEM, distance to road and water). Questionnaires were used to examine the potential of effective land-use planning. The results of the classified Landsat images indicate that land use and cover distribution over Landzun - Bida exhibited more concentration of built-up area on the wetland as compared to Chanchaga-Minna and Kontagora. At Landzun-Bida, the built-up areas occupied 12.35km2, while at Chanchaga - Minna, it occupied 8.2km2, and in Kontagora, it is 7.8 km2 between 1988 and 2018. Wetland depletion shows that 3.11km2 for Bida, 206.24 km2 for Minna, and 103.53 km2 for Kontagora are left in 2018, respectively. The simulated results on the wetlands indicate that Minna would have the largest built-up area of 1610.3538km² (42.91%), followed by Kontagora 801.1656 (Km2 ) 39.59% and Bida 25.6617 (Km2 ) (73.67%) in 2030. The implication is that wetland areas would decrease to 4.32km2 in Minna, 1.16km2 in Bida and 4.23km2 in Kontagora by the year 2030. It is paramount to note that human settlements are increasing to wetland areas across the study locations. The conclusion is that spatiotemporal change in wetland land use and the land cover showed that the wetlands changed into different land use and land cover types due to population increase, farmland cultivation and increased built-up areas due to continuous urbanization. Therefore, it is recommended that human activities (both individuals and government) that degrade wetlands should be reduced, restricted or regulated. Also, the focus should be shifted from the immediate benefits derived from conversion to future and sustainable benefits derivable from proper wetland utilizations.