Rainfall Variability in the wet-dry seasons. An analysis in Batticaloa District, Sri Lanka

Rainfall is of primary importance to both the physical and cultural landscape of any region. The objective of this study is to find the trends for rainfall variability on climate change in Batticaloa District of Sri Lanka, by analyzing 146 years of monthly data of rainfall received during the period 1869-2014 from the meteorological station of the Department of Meteorology. Some studies attribute extreme events to rainfall variability due to climate change induced by global warming. However, there is a dearth of climatological studies addressing the trends in rainfall over Sri Lanka in support of such attribution. In our study, statistical analysis such as linear and standard deviation for 3 year, 5 year, 11 year and 21 year periods were utilized to examine periodic rainfall changes in both annual and seasonal contexts. The study finds that the 3, 5 year moving average shows high drier seasons, but the 11, 21 years moving average show higher wet seasons during the period of study. The changes of rainfall are known to have led to disasters such as flood and drought. Annual rainfall varies from 864 mm to 3081 mm, the distribution of which has sight variation throughout the district.