Urban Sprawl and Land-Use Transformation in Karachi (2000–2025): Satellite-Based Analysis and Impacts on Peri-Urban Areas

Abstract

Karachi, Pakistan's largest and most important economic hub, has undergone one of the fastest rates of urbanization in South Asia over the past 25 years. This research uses a combined quantitative and qualitative approach to assess urban sprawl and land-use/land-cover (LULC) change in the city of Karachi between 2000 and 2025, and the socio-economic and environmental impacts of unplanned urban development on the city's peri-urban areas. The quantitative component uses multi-temporal Landsat satellite data (2000, 2010, 2020, 2025) processed through supervised classification and change detection analysis in a geographic information system (GIS). The Shannon's entropy index is calculated to assess the extent and pattern of urban growth. The qualitative analysis is based on semi-structured interviews with 10 peri-urban residents and stakeholders, using thematic analysis. The results show that Karachi's built-up space grew from around 729 km² in 2000 to an estimated 2,050 km² in 2025, almost tripling in size, mostly at the cost of agricultural land, vegetation and other bare land. Shannon's entropy has grown from 0.52 in 2000 to 0.97 in 2025, reflecting a high level of diffuse, unplanned urban sprawl. Qualitative results highlight six types of peri-urban impacts: environmental, housing and infrastructure, water and sanitation, economic, agricultural, and urban heat island. The research provides evidence-based suggestions for integrated urban development and peri-urban governance in Karachi.