Trend and Variability Analysis of Rainfall and Extreme Temperatures in Burundi
Marc Niyongendako *
Institute of Mathematics and Physical Sciences, University of Abomey-Calavi, P.O. Box 613, Porto-Novo, Benin.
Agnidé Emmanuel Lawin
Laboratory of Applied Hydrology, National Institute of Water, University of Abomey-Calavi, P.O. Box 2041, Calavi, Benin.
Célestin Manirakiza
Ecole Normale Supérieure du Burundi, P.O. Box 6983, Bujumbura, Burundi.
Batablinlè Lamboni
Institute of Mathematics and Physical Sciences, University of Abomey-Calavi, P.O. Box 613, Porto-Novo, Benin.
*Author to whom correspondence should be addressed.
Abstract
This study investigated the variability and trend of rainfall and extreme temperatures over three eastern and northeastern regions of Burundi during the period 1980-2015. Data used were collected from seven stations belonging to the geographical institute of Burundi. Annual and seasonal variability are assessed using standardized anomaly, coefficient of variance and precipitation concentration index. In addition, non parametric statistic tests Mann Kendall and Sen’s slope estimator are used to detect trends in rainfall, maximum and minimum temperatures. The results reveal a high monthly and inter-annual variability of rainfall whereas the temperature does not show high fluctuation at monthly scale. The northern region presents the lowest amount of rainfall for the first rainfall season (October-January) when drought is frequently observed. No significant rainfall trend detected over all regions at seasonal and annual scales whereas significant increasing trend was observed for both maximum and minimum temperatures over all regions. The spatial distribution of rainfall and extreme temperatures displays also a wide variation across the region depending on topography of the study area.
Keywords: Burundi, variability, trend, rainfall, extreme temperatures.