Dar es Salaam is one of the fastest growing cities in Africa, with an annual population growth of over 5%. In 2002 there were approximately 2.5 million inhabitants, increasing to 4.4 million in 2012. The population is expected to exceed 10 million by 2040, making Dar es Salaam a megacity. Urbanization is largely unplanned, and more than half of city residents live in informal settlements. The poorest citizens who settle in these areas not only have least access to basic services, but are also the most exposed to natural hazards.
Severe flooding in December 2011 - January 2012 displaced at least 10,000 people in Dar es Salaam and caused 40 deaths. Heavy rains in April 2014 also led to widespread flooding and infrastructure damage. Climate change is expected to exacerbate these trends, as Tanzania’s coastal region is likely to experience heavier, more concentrated rainfall events. Increasing frequency of floods, landslides, and other hazards is expected to impact most the fragile, unplanned parts of the city.
In 2015 HOT will begin an initiative to mapping infrastructure data in various parts of Dar es Salaam. This exposure data will be combined with flood hazard data to conduct risk analysis of potential future disasters. Throughout the year, the local OSM community will be strengthened through mapping activities and trainings, building capacity in community mapping techniques and risk analysis with the aim of improving awareness and resiliency to natural threats.