Changes in temperature and precipitation in the Bani watershed, a sub-basin of the Niger River

Since 1970 Africa has experienced a significant change in climate. It has resulted in a sharp decrease in rainfall but also an increase in temperature. The study looked at 36 climate indices derived from daily meteorological data of rainfall and temperature in the basin of the Bani in Mali (130 000 km(2)). The detailed description of the evolution of the climate in this area since 1950 has been conducted in terms of statistical analysis of mean variables but also extreme variables. Results show significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. The entire study area shows a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Indices derived from daily maximum temperature show less significant differences. Changes in precipitation derived indices show a downward trend. Globally, the changes occurred first on the indices related to rain (around 1970), and then on the indices related to temperature (around 1980).