Application of Landscape Metrics to Quantify the Magnitude and Patterns of Urban Expansions: Central Fragile Area, Sri Lanka

Urban expansion is a complex spatial process that transforms non-constructed areas into constructed areas. Often, they occur in environmentally sensitive areas and may cause serious environmental issues. This study examines the urban expansions in the Central Fragile Area (CFA), of Sri Lanka in order to help manage the process. For this purpose, the built-up areas considered as indicators of urban expansion are extracted from Landsat images for 1997, 2010, and 2020. A set of landscape metrics are used for the purpose of revealing the magnitude and patterns. The study is divided into six concentric zones with eight directions by applying the gradient analysis. Each metrics was analyzed through concentric zones and the relationship between them were analyzed by Pearson Correlation Analysis. The results indicate that the urban expansion of CFA has continuously increased from 1997 and the patterns of density, distance, complexity and aggregation are highly significant with types of expansion (infilling, edge expansion and outlying expansion). This study offers information on the magnitude and patterns of the urban environment and directs towards sustainable urban developments.