Fig. 3

(a) Mean annual rainfall amount (mean = 818.9 mm, SD = 144.5 mm) and (b) standardized time series of rainfall for Boulgou Province (1980 to 2012). Note that the inter-annual variability of rainfall was generally high within the study period. However, below normal rainfall was recorded in 1980 to 1988, while the reverse was the case in 2007 to 2010