Urban Flooding in the Northern Part of Kabul City: Causes and Mitigation

Urban flooding is a big challenge in the northern part of Kabul city. Urban flooding during monsoon has become common in recent years. Urban flooding occurs due to excessive rainfall and inadequate drainage, which can be exacerbated by unsustainable urban expansion, changes in catchment topography, and increase of impervious surface. Over a decade, drainage systems of Kabul had been undesirably upgraded in proportion to population growth, causing an increase in the frequency of urban flooding. However, studies to address this issue are not known to have been conducted in Afghanistan. Therefore, the objective of the study was to evaluate pre and post-development land-use changes and hydrological modeling for identification of the factors causing the floods. The land-use changes of between 1964 and 2009 were evaluated using CORONA 1964 and update 2009 imagery of Kabul city. Climate Hazard Group InfraRed Precipitation with Station (CHIRPS) rainfall data was used as input in a one-dimensional hydrological model for the simulation of floods. The simulated data were analyzed together with landuse change data for identification of driving factors of floods and the possible mitigation measures. The study revealed that green land (pervious surface) within the study catchment in Kabul City has reduced from 21 to 5.71%, while the impervious land has dramatically increased from 7.1 to 58.57% during 1960 ‑ 2009. Simulation of runoff using hydrological model revealed less runoff volumes generated floods in recent years which may be due to large changes in landuse. The study concludes that unsustainable development, a poor link between the main canal and existing drainage structures, and undesirable combined drainage structures are the major contributors to urban flooding of Kabul.