Abstract
Climate change has severe impacts on natural resources, food production and consequently on food security especially in developing countries. Likely accentuated by climate change, flooding is one of the disasters that affects people and destroies agricultural land and products. At different governance levels and scales, appropriate responses are needed. Cluster analysis using scaled at-site characteristics was used to determine homogeneous rainfall regions. A methodology for detecting change was applied to heavy daily rainfall of 34 stations across the Ouémé basin, Benin, in order to assess potential change in its characteristics. The spatial variability of the detected changes in return periods was analyzed using the kriging interpolation method. For this analysis, up to 92 years (1921–2012) of rainfall data were used. Three homogeneous regions were found by the cluster analysis. For all studied return periods, 82% of the stations showed statistically significant change in daily precipitation, among which 57% exhibited a positive change and 43% negative change. A positive change is associated with an increase in heavy rainfall over the area of concern. An analysis of the interpolated change in heavy rainfall of different return periods revealed an east-west gradient from negative to positive along the lower Ouémé basin (Region 2). From the middle to the upper Ouémé (Region 1 and 3), a decreasing tendency of heavy rainfall is dominant mainly for the non-homogeneous period. This result of the complex pattern of changes could be veritable information for decision makers and consequently for development of appropriate adaptation measures.
Highlights
Heavy rainfall events are one of the natural hazards that lead to degradation processes like flash floods or flooding as well as severe soil erosion, which can have regional devastating power and pose a serious hazard to lives and property
The Principal Component Analysis (PCA) was used to find the number of components based on the longitude, the latitude, the altitude and the mean annual rainfall (MAR) of each station
K-means and PCA clustering analyses were performed and three homogeneous rainfall regions were found in the Ouémé basin
Summary
Heavy rainfall events are one of the natural hazards that lead to degradation processes like flash floods or flooding as well as severe soil erosion, which can have regional devastating power and pose a serious hazard to lives and property. From 1900 to 2006, floods in Africa killed nearly 20,000 people and affected approximately 40 million more, and caused damage estimated at about US$4 billion [1]. Between 1980 and 2009, there have been 14 major floods affecting a total of 2.26 million people [2]. According to the World Health Organization, an estimated 500 thousand people are at risk of flooding [3]. The floods in 2008 and 2009 caused widespread damage and displacement, affecting around 158 thousand and 120 thousand people, respectively [2]. Floods have become increasingly frequent, leading to the question of whether this was due to the increasing frequency of heavy rainfall or changes in land use patterns [4]
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