Urban sprawl is reshaping metropolitan landscapes and placing increasing pressure on wetland ecosystems. Using Colombo, Sri Lanka as a case study, multi-temporal Landsat-based land use/land cover classifications for 1997, 2007, and 2017 were integrated with Cellular Automata–Markov land use simulation and Shannon entropy analysis to quantify historical urban growth and project future wetland exposure to 2060 under a business-as-usual scenario. Results indicate that built-up land has expanded sharply over the study period, while wetlands have declined by roughly one-quarter, indicating intensifying development pressure on ecologically sensitive areas. Model projections under a business-as-usual scenario showed continued urban expansion and a potential reduction in wetlands to less than one-fifth of their 1997 extent by 2060. Shannon entropy analysis reveals increasingly dispersed suburban growth alongside saturation in several core urban zones, confirming a spatial shift toward decentralized development. The combined results indicate rising wetland vulnerability, particularly in transitional peri-urban areas where future losses are likely to concentrate. These trends pose direct risks to flood regulation, stormwater retention, and microclimate moderation, underscoring the need for strengthened wetland safeguards, green infrastructure integration, and more controlled development strategies. The study demonstrates the utility of CA–Markov modelling for anticipating wetland vulnerability under urban expansion and provides evidence to support resilience-focused planning in rapidly urbanizing regions.
Jayasoriya et al. (Sun,) studied this question.