Where the City Ends: Morphology of Urban Sprawl in Metro Iloilo (1999-2019)

Abstract. Urban expansion in the Philippines has accelerated in recent decades and has exerted pressure on agricultural land, communities, and peri-urban governance. This study analyzes land use and land cover (LULC) change in Metro Iloilo using multi-temporal Landsat imagery (1999, 2009, 2019) processed in Google Earth Engine and classified with a Random Forest algorithm. Built-up areas increased from 1,919 ha (4.6%) in 1999 to 4,149 ha (9.9%) in 2019, largely replacing agricultural land, which declined from 64.5% to 55.0%. Intensity Analysis (IA) revealed that (i) urban growth accelerated most rapidly between 2009 and 2019; (ii) agriculture was consistently the most targeted class for conversion; and (iii) built-up expansion was highly systematic, with gains in Pavia and Oton exceeding expectations under uniform change. Morphological analysis further showed dual sprawl dynamics: contiguous growth radiating from Iloilo City’s core and leapfrogging clusters emerging in Santa Barbara and San Miguel. These findings highlight the urgency of integrating remote sensing-based monitoring with regional planning to manage sprawl, safeguard agricultural land, and guide more sustainable urban transitions in Metro Iloilo.