To this end, we analyze a large, consistent and reliable dataset of floods in Africa. Identification of causes is not easy given the diverse economic settings, demographic distribution and hydro-climatic conditions of the African continent. On the other hand, many African river basins have a relatively low level of human disturbance and, therefore, provide a unique opportunity
to analyze climatic effects on floods. We find that intensive and unplanned human settlements in flood-prone areas appears to be playing a major role in increasing flood risk. Timely and economically sustainable actions, such as the discouragement of human settlements in flood-prone areas and the introduction of early warning systems are, therefore, urgently needed.
Torrential rains and flooding affected more than 600,000 people in 16 West African nations in
Few years ago. The worst hit countries were Burkina Faso, Senegal, Ghana and Niger.
In fact, the economic damages caused by floods as well as the number of people affected by them has substantially increased in recent decades [Jonkman. The number of fatalities caused by floods in Africa during the period 1950-2009 . These numbers indicate a need for urgent actions, for the planning of which, we first need to understand the reasons why flood risk has strongly increased in Africa.
Flood risk is determined by (a) the probability that a flood may occur and (b) the potential adverse consequences. Therefore, herein we investigate the presence of climatic signals that may have increased flood probability, as well as the land use, economic and demographic changes that may have led to increased human vulnerability to extreme hydro-meteorological conditions.
And to isolate a climatic signal in flooding, we need long- term runoff records, which should be both reliable and reasonably representative of natural river basin conditions.
The behavior of African floods during the Twentieth Century was further tested by analyzing individual time series of annual maximum flow using at-site linear regression.
However, it is worth noting that the efficacy of the concept of statistical significance with respect to trend testing is being increasingly questioned and less value should be ascribed to the purported “significance” of the trends than to their direction and magnitude.
Based on the results of both continental and at-site analyses, we find that the magnitude
of African floods has not significantly increased during the Twentieth Century, and that climate has not been a consequential factor in the observed increase in flood damage.
Having detected no significant climate influence, the analysis focused on flood vulnerability. In the last 50 years, the African continent, as well as many other areas around the world, has undergone widespread and intensive urbanization. The total and urban population in Africa during the period is increasing at an alarming rate.
A Guest Editorial