Assessment of Land Use/Land Cover Change and Morphometric Parameters in the Keta Lagoon Complex Ramsar Site, Ghana

Abstract

The rapid urbanization, industrialization, agricultural activities, and increasing trend of some natural hazards, such as climate change, particularly in coastal areas, necessitate the continual assessment of critical but fragile ecosystems like that of the Keta Lagoon Complex Ramsar Site (KLCRS). This productive ecosystem in Ghana faces serious threats from intensive exploitation, physical modification, changes in water regime, and water pollution. The current study employed geospatial and intensity analysis to assess the pattern of land use/land cover (LULC) change for almost the past three decades and morphometric parameters of the KLCRS landscape. Landsat Satellite images for 1991, 2007, and 2020 were acquired to uncover the pattern of LULC change, while morphometric changes were assessed using global Advance Space Thermal Emission and Radiometer (ASTER) digital elevation model (DEM) data and the spatial analyst tools in GIS software. The result established that the acceleration of land transformation was intensive between 2007 and 2020, which could be linked to population growth and increased socio-economic activities. There was a net gross gain of built-up that originated largely from the conversion of marsh, dense vegetation, and cultivated land. Prior to this period, cultivated land recorded net gain (125.51 km2) between 1991 and 2007, whereas dense vegetation and marshland showed a net loss of 151.37 km2 and 2.44 km2, respectively. The gain of cultivated land largely targeted marshland in both time intervals. The construction of saltpans contributed largely to the small increase in water extent. The morphometric analysis revealed the groundwater potential of the KLCRS. The low-lying nature of the landscape makes the area susceptible to coastal flooding. The trend of the observed changes could invariably affect the ecological integrity of the landscape, hence suggesting the need for immediate preparation and implementation of marine and coastal spatial plans by relevant stakeholders.

Changes in urban green spaces in coastal cities and human well‐being: The case of Cape Coast Metropolis, Ghana

“…The output of the accuracy assessment showed an overall accuracy of 95% for 1991 and 85% for 2018. The Kappa coefficient (0.93) for the year 1991 and that of 2018 (0.8) were of acceptable agreement (Appiah et al, 2015; Duku et al, 2021). The recommended threshold for accuracy of land cover categorisation (85%) was met by our classification (Thomlinson et al, 1999).…”

Land use and land cover changes implications on biodiversity in the Owabi catchment of Atwima Nwabiagya North District, Ghana

“…Landsat images of 1991 (Landsat 5), 2001 (Landsat 7), 2011 (Landsat 7), and 2021 (Landsat 8) were downloaded from the United States Geological survey's website. The selection of the satellite images was influenced by availability of the images, the spatial resolution, and the overall quality of the images in terms of those with low cloud and scene cover [ 38 ]. To be compatible with QGIS Imagine files, the raw data satellite images were transformed from zip files using WinRAR which extracted the images into various bands and stored for further processing [ 39 ].…”

“…Atmospheric correction was then performed to extract the surface reflectance of the individual bands in the Landsat images to improve accuracy of the classification [ 39 , 42 ]. The individual bands in the Landsat images were layer stacked and projected to Ghana Meter Grid [ 38 ]. A shape-file of the Owabi catchment received from the District Assembly within the catchment area was used to sub-set the area of interest from the Landsat images.…”

“…Using a sample of 97 of the ground control points and from Google Earth imagery for each year, the study validated the classified images. This was achieved by calculating and analyzing the accuracy and Kappa statistic of each classified image [ 38 , 46 ].…”

Coastal Zone Changes in West Africa: Challenges and Opportunities for Satellite Earth Observations

“…Today, there is increasing demand for natural hazard management in coastal areas (Goussard and Ducrocq 2014;Alves et al 2020;Dada et al 2021). Lowlying coastal areas, estuaries, and deltas are most vulnerable to coastal flooding (Nicholls and Tol 2006;World Bank 2020;Duku et al 2021). Sea-level rise, coupled with an increase in the intensity or frequency of extreme events, will have severe effects on coastal development (IPCC report, Oppenheimer et al 2019).…”