Disaster-resilient cities: temporal analysis of urban land use land cover changes and urban floods from 1999 to 2022: case study of Colombo, Sri Lanka

Abstract

This study examines the land use land cover (LULC) changes in Colombo City from 1999 to 2022, focusing on the effects of rapid urbanization on urban flood frequency and severity in the Colombo Municipal Council (CMC) area. Using high-resolution satellite imagery from Landsat 5-8, the study tracks and classifies land use over three decades, revealing significant urban expansion, a reduction in green spaces, and the loss of natural water retention zones. These changes have led to increased surface runoff, exacerbating the risk of urban floods. The research highlights that urbanization, coupled with the inadequacy of drainage infrastructure, especially in informal settlements, has contributed to the growing flood vulnerability in the city. LULC maps generated through maximum likelihood classification were validated with high accuracy, confirming the reliability of the data. Correlation analysis suggests a moderate relationship between certain land cover types (e.g., water bodies) and flood impacts, though other factors such as drainage efficiency and urban planning are more critical in determining flood risks. The study underscores the need for improved drainage systems, preservation of green spaces, and comprehensive urban planning to mitigate flood hazards. The findings emphasize the importance of integrating climate adaptation measures into urban planning, with a focus on sustainable land management and infrastructure development. The research concludes that a holistic, resilience-based approach is crucial for building a climate-resilient city capable of adapting to ongoing urbanization and climate change impacts.