Urban Flooding and Climate Change Vulnerability-A Case Study of North Karachi

Abstract

rban flooding in Karachi has been exacerbated by insufficient climate resilience measures, inadequate urban planning, and underdeveloped drainage systems. These deficiencies have led to widespread flooding in residential and commercial areas, causing significant damage to infrastructure and amenities. North Karachi, a densely populated suburb, is particularly vulnerable due to its proximity to major water bodies such as the Lyari River (LR) and Gujjar Nala (GN). The area's elevation ranges from 5 to 96 meters, creating a natural slope towards the southeast, making areas in this direction, including UCs 3, 5, 6, and 8, highly prone to flooding. This vulnerability is further influenced by the geographical layout, with the Lyari River and the surrounding Pub Ranges affecting rainfall runoff patterns. To evaluate flood vulnerability in North Karachi Town, various analyses were performed. Elevation data, sourced from Google Earth Pro, was converted from vector to raster format using ArcMap’s interpolation tool. This analysis revealed a slope from the northwest to the southeast, influenced by the Pub Ranges to the west and the Lyari River to the east. UCs 4, 7, and 9 are especially at risk due to their lower elevations and proximity to the Lyari River. The Normalized Difference Vegetation Index (NDWI) was employed to assess vegetation stress. Pre-monsoon NDWI values ranged from -0.26898 to -0.04352, indicating severe water stress. Post-monsoon values ranged from -0.2021 to 0.04597, with the maximum value of 0.04597 corresponding to humid and flooded conditions. The study highlights the crucial need to maintain clear waterways to manage flood risks effectively. Authorities should focus on ensuring that drains and river channels are free of debris and encroachments to mitigate future flooding.