Climate Change and Rainfall: Part II

My previous blog explored the impacts of climate change in rainfall in terms of droughts, and more specifically in West Africa and the Sahelian region. This blog continues to explore the impacts of climate change in Africa but in terms of floods. The first thing that comes to my mind when I associate climate change with rainfall in Africa are the ideas of drought and famine, thus ideas concerning extreme rainfall and increased flood extent, I find, is very intriguing. In this blog, I want to look at floods associated with climate change and the impacts.

The dominant projections of climate change impacts on rainfall in terms of extreme rainfall and flooding events is that rainfall is more likely to become highly variable in East Africa, extreme rainfall events will become more frequent and thus result in more flooding (IPCC, 2007). Studies such as Webster et al. (1999) and Hastenrath et al. (2007) have found that in fact, East Africa has experienced both extreme rainfall as well as a lack of rainfall in the region. This anomalous extreme rainfall results in more flood events, and the frequency of flood events has increased in recent years. Shongwe et al. (2009) analysis of the International Emergency Disaster Database shows that almost 7 events per year of reported disasters, which was related to increased flooding, had occurred from 2000 to 2006. The impacts of these disasters affects economic development, poverty reduction and the well-being of an average of two million people per year (Shongwe et al., 2011). Shongwe et al. (2011) notes that the predicted impacts of global climate models are already occurring now, much sooner than anticipated. And so, the impacts of flood risk need to be analysed, and management of flooding regimes must be properly accounted for. Just because there is an expected increase in East Africa does not mean that this is necessarily a good thing.

The coastal city of Mombasa is located in Kenya and currently experiences frequent floods on a near-annual basis, however the October 2006 flood was one flood that Mombasa did not usually experience. This flood was induced by extreme rainfall which saw the destruction of important infrastructure, such as collapsed and flooded roads which can be seen in the image below, and more than 60,000 people was affected by the flood (Awuor et al., 2008). The impacts of this large flooding event worsened the social and economic conditions of the city due to the major economic losses associated with infrastructure damages, as well as the damages to fishing vessels. A large majority of Kenya’s coastal population is concentrated in Mombasa – this increased the risk of the spread of cholera (Awuor et al., 2008). The city was notified of a cholera alert whereby thirteen cases were found positive for cholera and an addition of two deaths by the 11 November 2006 (OCHA, 2006). Moreover, between 15^th and 17^th October, high rainfall levels of 110mm resulted in landslides which saw the death of five children.
The impacts of flooding are very severe in the short run in that homes are almost instantaneously destroyed, many people are displaced and the death rates of populations are widespread and the causes of these deaths range from drowning, debris or from water-borne diseases like cholera. These impacts only proves to show that flood management in vulnerable places is integral in a warming world.

 Image 1 (Left) and 2 (Right) 

There is no doubt that the increases of the number of floods in magnitude and frequency are causing huge damages to infrastructure, economic performance and livelihoods. However, some argue that the damage and extent of flood events is more than just the increased intensity and magnitude of floods as a result of climate change in recent years. Studies such as Baldassarre et al. (2010) concluded that at continental and site specific scales across Africa, the impact of climate change in this observed increase in flood damages is negligible. Instead, Baldassarre et al. (2010) attribute the increased damages of floods to higher rates of urbanisation in the last decade. They found that an increase in urban population by magnitude of 1 also saw the increase of fatalities caused by floods by a magnitude of 1. Many studies (Hardoy et al., 2001; Douglas et al., 2008; Jonkman, 2005) concluded that the increased potential of flood risk with severe and irreversible consequences is a result of intensive, rapid and unplanned urbanisation in the number of people living in floodplain areas (Balassarre et al., 2010). For example, the growth of the capital city of Lusaka in Zambia is prone to flooding, thus this growing city is expected to have higher risks to flooding (Nchito, 2007).

Concluding Thoughts:

It is very important to not take these projections of increased flood frequency and magnitude lightly, given that they are currently happening now and not in some far distant future. Proper flood management is required to minimise the impacts of these floods induced by climate change. However, as many studies found, it is difficult to isolate and differentiate the increased flood damages as a result of climate change only. Other human factors showed to account for a large part of this increasing damage, even in a globally warming world. Even though climate change may induce frequent floods, climate change should not be seen as the only cause of the increased impacts of floods in many African towns and cities. Overall, compared to droughts, the impacts of floods on many people can be minimised with the proper management of drainage systems and the construction of towns in a rapidly urbanisation, as well as working in tandem with monitoring rainfall patterns and thus predicting then floods are likely to occur as a result of intense rainfall periods.