Geo-Spatial Analysis of Urban Wetlands Loss in Obio/Akpor Local Government Area of Rivers State, Nigeria

Abstract

Urban wetlands make cities livable in many important ways. They reduce flooding, replenish drinking water, filter waste, provide urban green spaces, and are a source of livelihoods in most urban areas. This study aims to geo-spatially analyze urban wetland loss in Obio/Akpor Local Government Area (LGA), Rivers State, Nigeria. The study analyses land use /land cover changes (LULC) using Landsat7 UTM images of 2000, 2009 and 2018. The satellite images covering the area were acquired and analyzed using ArcGIS10.6. A total area of 25,773.39 sq km was delineated in the study area. After processing the imagery, five LULC classes where developed in ArcGIS environment, such as wetland, built-up area, vegetation, water bodies and bare surface. The study shows that the urban land-use of Obio-Akpor LGA had changed dramatically during the period of 18 years. In 2000, wetlands occupied the second-lowest classes with 9.12% (2352.15 sq.km) of the total classes due to high level of urban development in the area while built-up areas occupied the third-highest classes with 17.62% (4543.83 sq.km) of the total classes. In 2009, the study revealed that the built-up area (urban land use) rose to 19.3% (4975.11 sq.km) and maintained an increase in urban growth due to changes from constructions of many roads and houses while wetlands also surprisingly experienced an increase and occupied the third-highest classes with 19.17% (4942.26 sq.km). Evidence from the study show that 2018 witnessed an expansion in terms of developmental activities in all facets as the built-up area increased in three-fold size within the year, bare surface reduced to a class of 15.47% (4057.29 sq.km) forcing developers to develop towards the wetland ecosystem. The wetlands, therefore, experienced a sharp decline to 4.91% (1266.75 sq.km) due to rapid conversion of wetlands for housing development and excessive urban sprawl and its associated problems of inefficient use of land, urban space and the development of shanty towns/slums. The study concluded that there is a need for the wise use of wetland resources and improvement of institutional arrangement so that wetland policies can be fully integrated into the planning process across all disciplines.

Impact of Land Use and Land Cover Changes on Urban Ecosystem Service Value in Dhaka, Bangladesh

“…Since the built-up area derives no ecosystem service value, the total ESV declined due to the development of the built-up area during the past three decades. A similar scenario is also evident in some other studies showing the development of the built-up area through the conversion of agricultural land [85], forest, and vegetation [86] and waterbodies [87].…”