Characterization of Hydroclimatic Risks in the Lower Ouémé Valley in Benin

Abstract

The lower Ouémé valley is subject to the effects of hydroclimatic hazards which negatively affect the activities of the populations. This research aims to characterize hydroclimatic risks in the lower Ouémé valley. The methodological approach consisted of determining the hazards linked to hydro-climatic variability through climatological (rainfall, ETP) and hydrometric (flow) data from 1960 to 2011, the study of standardized precipitation indices and the analysis of the break in stationarity of rainfall and hydrometric series supported by field observations and socio-anthropological investigations. She also tackled the frequency analysis of extreme climatic events with the adjustment of the laws of Gumbel and GEV. The study of the seasonal variability of the hydrological regime, the maximum rainfall levels over the period 1960-2011 and the socio-anthropic data collected, shows that the lower Ouémé valley is under the threat of hydroclimatic disasters. The Gumbel and GEV diagrams produced show that the most frequent flood return periods are three (03) years and the rare ones are fifty (50) years. The frequency of droughts varies to varying degrees. It is from 1.92% for extreme droughts to 9.61% for severe droughts and 42.31% for moderate droughts. Farmers’ perceptions of hydroclimatic phenomena relate to the changes that have occurred in certain animal and plant species, the disruption of the hydrological regimes of waterways, the reduction in the number of rainy days and the drying up of watercourses. Keywords: Lower Ouémé Valley, Hydroclimatic Risks, Perceptions, Endogenous Knowledge, Adaptation Strategies.