Urban flooding and waterlogging in the northern part of Kabul City

Abstract

Urban flooding and waterlogging are the big challenges in urban areas of Afghanistan especially in the northern part of Kabul city. Such flooding during monsoon become common in recent years. Urban flooding occurs due to unsustainable urban expansion, change in catchment topography, and increase impervious surface, poor link between catchment drainage structures. Obstruction of the drainage structures leads to waterlogging so that stormwater overspills and blocks the roads against traffic and businesses. Over a decade, drainage systems had been undesirably upgraded in proportion to population growth, caused an increase in frequency of urban flooding and waterlogging. However, very few studies have been conducted to address this issue. Therefore, the objective of the study was to evaluate pre and post-development land-use changes and delineate flooding prone area, identify the factors causing urban flooding and waterlogging and finally, to identify catchment discharge from the rainfall using HEC-HMS. For this purpose, land-use changes over 45 years of pre and post-war periods (1964-2009) were evaluated using CORONA 1964 imagery with new update 2009 imagery 10x10cm resolution of Kabul city. Climate Hazard Group InfraRed Precipitation with Station (CHIRPS) and the ministry of energy and water (MEW) rainfall data set were used to estimate discharge from rainfall. The land-use changes scenarios were analysed by using geographical information system (GIS) under the causes of the increase of urban flooding. The results revealed that unsustainable development activities in the natural water flow path are the major cause of increasing flood in the study area. There are other factors as a poor link between Wazerabad canal and existing drainage structures, catchment characteristic, undesirable combined drainage structures law enforcement and less attention to maintenance which contribute to urban flooding and waterlogging. The study suggest that the sub-drainage structure should be linked to Wazerabad canal by considering sufficient slop, segregation of sewer system where applicable, public awareness, structural and non-structural approaches for urban flood mitigation , law enforcements, sediment and solid waste trap at each drainage inlet as well as system cleaning and maintenance after each rainfall are recommended.