Assessing the impact of urbanisation on storm water runoff peak flows in Bogotá

Abstract: Due to internal conflicts and an economical conversion in the mid 1900’s, the Colombian society has seen a great social transition from rural to urbanised in the last 50 years. Apart from positive impacts of urbanisation on social factors, there are hydrological issues coupled to it. With the aim to assess the impact of urbanisation on runoff peak flows in Bogota, the historical change in impervious cover and increase in drainage efficiency through the years 1979-2013 have been studied. The curve number- and triangular unit hydrograph-methods were used to determine pre-development flows, while the urban peak discharge formulas (USGS, 1984) were used to determine post-development flows. Eight sub-basins located in the most urban parts of Bogota have been subjected to the study, and results show an increase of at least 100% in peak flows in all watersheds, with one exception, and up to 500% in others. Solutions of both constructional and political sorts have been suggested, including subventions for investments in sustainable urban drainage measurements, and green roofs and permeable pavements. However, good social conditions, equality, and knowledge among the population is key to a better water resources management. It has been concluded that the urbanisation and increase in drainage efficiency in Bogota has had great impact on the runoff peak flows in Bogota, and that different types of measures are required to withstand further impact on the hydrological cycle