NEWSLETTER #44 - SOCIETY OF AFRICAN EARTH SCIENTISTS

 

 

Volume 11, Issue 3,  July-September 2022

 

CONTENT

Chair's Foreword

Increasing Frequency of  Extreme Flood Events in African Urban and Rural Areas

Earth Science Events

References and selected reading

 

Chair's Foreword*

In this issue we report on marked increase in the frequency of extreme flooding events on the continent, and in West Africa particularly. The report is timely as 2022 has been one of the worst years on record for the continent in terms of  urban flooding due to extreme rainfall.

 

 

Increasing Frequency of Extreme Flooding Events in African Urban and Rural Areas

In recent years we have seen the increasingly more frequent flooding of urban areas in Africa, and West Africa in particular.

   Toure [1] notes recent West African flood events in Abidjan (May 2017, June 2018), Ouagadougou (2009, 2015) and Dakar (2009, 2017) as well as other major capitals (Lagos, Accra,etc). We can presently add to this series of extreme events in noting that the recent 2022 floods occurring throughout West Africa have displaced over a million people in Nigeria alone and resulted in the loss of hundreds of lives [2]. Ayesha Tandon in Carbon Brief, November 2022  succinctly reports on the research of Otto et al [3] which claims that the deadly level of rainfall in the region in 2022 was made 80 times more likely due to climate change.

   In Nigeria the flood waters displaced over a million people and over a million hectares of farmland were damaged. Food security in the region was also negatively impacted due to the rise in prices as crops failed and yields fell.

   In Nigeria and Niger the floods were amongst the deadliest on record. Chad declared a state of emergency faced with the heaviest rainfall in 30 years. The release of Cameroon's Lagdo Dam exacerbated matters  and the emerging trend in the impact of dams in relation to the increased risk of flood due to climate change needs to be accorded critical and serious monitoring, especially where dam is part of an infrastructure scheme that is not complete; as in the case of the Lagdo Dam, which was supposed to be accompanied by the construction of another dam in Nigeria, which is still not built.

   Otto and colleagues' climate science work partly addresses a new area of climate science known as "attribution", which attempts to establish the "fingerprint" of climate change on extreme weather events. This would appear to place climate science on a more rigorous footing where the input of climate change can be established and quantified.

   To conduct attribution studies scientists use models to compare the world as it is today with an ideal world that is untouched by human activity, and without human induced climate change. The study of Otto et al  attempts to establish the "signature" of climate change in West African rainfall.

   The main causes of flooding in West African urban regions were identified by the study of Toure cited earlier from the CR4D programme:

- Abundant rainfall (the 2022 studies of Otto et al indicate that floods were caused by short intense storms)

- Permeability of the soil

- Saturation of the soil due to destruction of vegetation in urban and rural areas

- unsuitable/poorly maintained drainage/street gutters

- uncontrolled urbanisation and poor development planning of urban extension

 

As the studies indicate - we do in future years expect to see the continued increase in the frequency of extreme and very extreme weather events. The CR4D study  by Toure suggests urban African regions can be made more sustainable by the promotion of more green spaces such as public parks and gardens especially in storm basins and flood prone areas. Also the option is there to promote the vertical extension of West African cities.

   Another more recent study by Turay [4] suggests that little attention is paid to ecosystem based measures to tackle flood hazards, and they are not used in managing flood events. The study usefully suggests  the need for intra-african learning from observing how different countries in Africa tackle extreme flooding and noting which strategies are more successful, and those not so successful.

 

Earth Science Events

December  13, 2022

International Conference  on Agriculture, Biotechnology, Biological

and  Biosystems Engineering

VISION:  

VENUE: Cairo, Egypt

 

 

References

[1]  Toure, N. E., Flood risk reduction under Paris agreement (FLORR-PA) for three West African capital cities, Climate Research for Development (CR4D), end of grant workshop presentation, 21-23 June 2021, Nairobi, Kenya.

[2] Tandon, A., West Africa's deadly rainfall in 2022 made "80 times more likely " by climate change,  Carbon Brief, November 2022.

[3] Otto, F., et al, Climate exacerbated heavy rainfall leading to large-scale flooding in highly vulnerable communities in West Africa, ResearchGate, 2022.

[4] Turay, Bashir, Flood hazard management in a multiple hazard context: a systematic review of flood hazard management during the COVID-19 pandemic in Africa, Discover Water 2, Article number:6 (2022)' https://doi.org/10.1007/543832-022-00014-w

 

 

*Board of the Society of African Earth Scientists: Dr Enas Ahmed (Egypt), Osmin Callis (Secretary - Guyana/Nigeria), Mathada Humphrey (South Africa), Ndivhuwo Cecilia Mukosi (South Africa), Damola Nadi (Nigeria), Dr Chukwunyere Kamalu (Chair - Nigeria).