Abstract
Abstract Urban communities in developing countries are one of the most vulnerable areas to extreme rainfall events. The availability of local information on extreme rainfall is therefore critical for proper planning and management of urban flooding impacts. This study examined the past and future characteristics of extreme rainfall in the urban catchments of Dar es Salaam, Tanzania. Investigation of trends and frequency of annual, seasonal and extreme rainfall was conducted, with the period 1967–2017 taken as the past scenario and 2018–2050 as the future scenario; using data from four key ground-based weather stations and RCM data respectively. Mann–Kendall trend analysis and Sen's slope estimator were used in studying changes in rainfall variability. Frequencies of extreme rainfall events were modeled using the Generalized Pareto model. Overall, the results of trend analysis provided evidence of a significant increase in annual and seasonal maximum rainfall and intensification of extreme rainfall in the future under the RCP4.5 CO2 concentration scenario. It was determined that extreme rainfall will become more frequent in the future, and their intensities were observed to increase approximately between 20 and 25% relative to the past. The findings of this study may help to develop adaptation strategies for urban flood control in Dar es Salaam.
Highlights
In recent decades, changes in climate have been evident all around the globe and the related impacts on the environment, societies, and economies have been significant (IPCC 2013)
Assessing the changes in extreme rainfall in the Dar es Salaam urban area is of great importance since events of extreme rainfall in the region are directly linked to flooding, property damage, and potential loss of life
The results obtained from this study show an indication of climate change
Summary
Changes in climate have been evident all around the globe and the related impacts on the environment, societies, and economies have been significant (IPCC 2013). The behavior of natural extreme phenomena, e.g. heavy rains, floods, drought, etc., have been studied for an extended period of time in different parts of the world, including the UK (Otto 2017), Canada (Li et al 2018), India (Gautam & Bana 2014), Tanzania (Kijazi & Reason 2009; Cioffi et al 2016), United States (Mallakpour & Villarini 2015), South Africa (Nangombe et al 2018), Czech Republic (Elleder 2015), etc All these studies show the importance of understanding the changes in climate extremes and related effects locally, regionally and globally. Households’ losses following the floods of April 2018 in Dar es Salaam were estimated to be over 100 million USD; representing 2–4% of the region’s gross domestic product (Erman et al 2019)
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