Impacts of urban impervious surface expansion on rice fields in north central province, Sri Lanka: a GIS-based temporal analysis

Abstract

Urbanization drives the increase of impervious surfaces, thereby significantly diminishing the rice field areas over time. This study examines the impact of urbanization on rice fields in Sri Lanka's North Central Province, particularly in the Anuradhapura and Polonnaruwa districts. Using quarterly Sentinel-2 satellite imagery and a pixel-based classification approach, the analysis incorporates remote sensing indices such as the Modified Normalized Difference Water Index (MNDWI), Enhanced Vegetation Index (EVI), and Normalized Difference Built-up Index (NDBI) to map and quantify the expansion of impervious surfaces. Conducted on the Google Earth Engine (GEE) platform, this research highlights a significant reduction in rice field areas between 2019 and the fourth quarter of 2023, directly correlated with the growth of impervious urban surfaces. The findings underscore the urgent need for effective land management strategies to mitigate the adverse effects of urbanization on agricultural land use. This study offers critical insights and recommendations for sustainable urban planning, with implications for food security, economic stability, and ecosystem health in the region.