Spatial-statistical Approach to Evaluate Land Use Change in Galle DSD, Sri Lanka

Abstract

This study attempts to identify how land use has changed over time in Galle Divisional Secretary Division (DSD) with emphasis placed on change in built-up land. Galle DSD which encompasses 22.4 km2 is a semi-urban area which includes Galle city area, the capital of southern Sri Lanka. Land use change in Galle DSD from 1983 to 1999 has been reviewed using the available maps considering the five key land use classifications for the area: homesteads, built-up land, agricultural land, non-agricultural land and water bodies. Geographical Information Systems (GIS) assisted spatial analysis revealed that, built-up land has remarkably expanded by 1.33 km2 (approximately 6% of total area) during the 16 years period observed in this study, mainly at the expense of homesteads and agricultural land. Built-up land expansion has been taking place mainly adjacent to the homesteads and the existing built-up land. Bivariate correlation analysis was performed in order to determine the relationships between the key land use classifications. Comparatively higher negative correlations were noted between the extent covered by homesteads and the two land use categories; agricultural land and built-up land and these correlations were statistically significant. The ratio of built-up land to agricultural land has become almost half during the 16 years period. This continuing replacement of pervious surfaces by impervious built-up areas being one of the major reasons for Galle DSD area to experience frequent flooding problems highlights the necessity to control the urban growth in a sustainable manner.