CHANGE DETECTION ANALYSIS FOR URBANIZATION OF BLANTYRE CITY, SOUTHERN MALAWI
Abstract
Changes in land use and land cover have occurred in Blantyre City, Southern Malawi, as a result of high urbanization and population growth. Understanding and quantifying the spatial-temporal dynamics of urban land use and land cover shifts, as well as the factors that drive them, is critical for developing appropriate policies and tracking processes for decision-making on urban development. By combining GIS and remote sensing techniques with land-use change modeling tools, urbanization patterns related to land use and land cover changes in Blantyre City were analyzed. ENVI software was used to preprocess satellite data from Landsat 4-5 TM for 1990, 2000, 2010, and Landsat 8 OLI for 2020. Land use and land cover maps were generated using the Maximum Likelihood Algorithm of Supervised Classification. To map the dynamics of Built-Up area and vegetation for the past decades, Normalized Difference Built-up Index (NDBI) and Normalized Difference Vegetation Index (NDVI) analyses were performed. A confusion matrix was used to determine the overall accuracy of classified land use and land cover maps, with results exceeding the minimum and appropriate threshold standard. The developed land cover maps were used with the Change Detection Analysis tool to measure land use and land cover changes, analyze land-use transitions between land cover classes, and identify built-up area gains and losses with other land cover classes, as well as assess the spatial pattern of built-up areas.
Finally, data interpolation was conducted in MS Excel to model and forecast potential urban land-use changes in Blantyre City. In general, the findings of this study indicate that built-up areas have expanded at the cost of vegetation and bare land over the last 30 years, rising from 12.87% in 1990 to 16.36% in 2000, then 20.67% in 2010 and 31.77% in 2020. In comparison to other directions, the spatial trend of built-up areas revealed a rising trend in the central west and eastern parts of Blantyre City, water bodies have shown a decreasing trend over the study period. Therefore, the findings of this study could provide decision-making for urban planning and other stakeholders interested in environmental studies related to land-use change analysis
Research summary
Understanding and quantifying the spatial-temporal dynamics of urban land use and land cover shifts, as well as the factors that drive them, is critical for developing appropriate policies and tracking processes for decision-making on urban development. The developed land cover maps were used with the Change Detection Analysis tool to measure land use and land cover changes, analyze land-use transitions between land cover classes, and identify built-up area gains and losses with other land cover classes, as well as assess the spatial pattern of built-up areas. In general, the findings of this study indicate that built-up areas have expanded at the cost of vegetation and bare land over the last 30 years, rising from 12.87% in 1990 to 16.36% in 2000, then 20.67% in 2010 and 31.77% in 2020. In comparison to other directions, the spatial trend of built-up areas revealed a rising trend in the central west and eastern parts of Blantyre City, water bodies have shown a decreasing trend over the study period.