Multi-temporal analysis of land use and land cover change detection for Dedza District of Malawi using geospatial techniques

Abstract

Land use and land cover (LULC) changes attributed to anthropogenic activities are one of the fundamental drivers of local, regional and global environmental changes. Studies of LULC have become vital in enhancing our understanding and monitoring of environmental change. This study analysed LULC changes dynamics for the years 1991, 2001 and 2015 using remote sensing and GIS in Dedza district of Malawi. In the analysis, both supervised and unsupervised classification algorithms were performed on each image. An overall accuracy of the classification achieved for the classified images was 91.86%. The results revealed that forest land, water bodies, wetlands and agricultural land drastically declined while built-up areas and barren land substantially increased between 1991 and 2015. The long-term annual rate of change declined for water bodies from 5.54% ha-1 to 1.74% ha-1 within the period of study. Likewise, the forest land, agricultural land and built-up area experienced increased annual rates of change from 1.71% ha-1 to 1.94% ha-1, 0.02% ha-1 to 0.11% ha-1 and 7.22% ha-1 to 9.80% ha-1 respectively. Post-classification comparison of the classified images based on the transition matrix indicated that approximately 61.48% of the total forest land in 1991 was converted to barren land in 2015 while about 2.70% of agricultural land in 1991 has been converted to built-up land in 2015. This study, therefore, provides reliable LULC data which captured the extent and rate of land use changes that has occurred in the Dedza district of Malawi for the period ranging from 1991-2015. It is believed that the trends identified in this study would be useful in guiding planners and decision-makers of land management and policy decisions geared towards a more sustainable natural resource management strategy in the Dedza district and other districts of similar setting. It is recommended that a study be undertaken to establish the apparent socio-economic and spatial drivers of the LULC changes between 1991 and 2015 over Dedza district of Malawi environmental changes (Lambin et al. 2003; Jensen 2005). According to IGDP (1999), LULC changes also reflect the culmination of interactions between climate, ecosystem process, biogeochemical cycles and other biodiversity indicators. Studies of LULC have therefore become vital to understanding and monitoring environmental change and related processes while these types of studies also provide valuable information that can be used to inform more sustainable natural resource management strategies. The LULC changes have significant environmental and socio-economic impacts especially for rural inhabitants involved in land-based livelihoods. The direct and indirect impacts of land use and land cover changes have also been linked to losses in wildlife, deteriorating biodiversity, changes in plant species composition, desertification, deforestation, changes to nutrient, carbon and water cycles, as well as unplanned urban expansion (Verburg et al. 2000; Lambin et al. 2001; Brooks et al. 2002; Verburg et al. 2004; Ifamitimehin and Ufuah, 2006; Maitima et al. 2010; Ujoh et al. 2011; Kamwi et al. 2015). An understanding of LULC changes is also important in the context of trying to unravel land use conflicts especially in cases where conflicts linked to competing land uses tend to escalate in proportion to rising population numbers.