Spatio-temporal analysis of land use/cover changes in the Pra River Basin, Ghana

Abstract

Pra River Basin, located in South Central Ghana, is a forest basin that is reported of being threatened with land degradation activities. This study evaluates past and present land use pattern of the basin and determines the spatial variation of land cover classes across it sub-basins. Landsat images, 1986, 1998, 2008, and 2018, were classified using the spectral angle mapping technique. Six land use classes were identified and classified, namely, closed forest, open forest, farm/grassland, settlement, mining, and water. The results showed that the basin has been experiencing changes in the spatial patterns and distribution of LULC classes. Generally, closed forest and open forest decreased with mean values of 10% and 11% respectively, towards settlement, farming, and mining which increased with mean values of 7.8%, 12.4%, and 1.0% respectively. Statistical analysis showed that the change in land use classes varied across the sub-basins. Settlement increased consistently in all the sub-basins; however, Oda and Upper Ofin increased greatly towards peri-urban residential and commercial land uses. Similarly, illegal mining activities recorded severe increase in Anum, Birim, Lower Ofin, and Twifu Praso sub-basins. Farm/grassland increased specifically in Lower Pra, Assin Praso, Twifo Praso, Birim, and Upper Ofin sub-basins. The main drivers identified in the study includes population growth and migration, response to socio-economic conditions and policies, and availability of mineral resources. The study illustrates the importance of sub-basin analysis in pinpointing areas at risk for both basin and local level management.