Abstract:
Analysis of long-term wet and dry patterns provides an abundance of information
on effective crop planning and water resource management, and a better
understanding of climate variability over time. This study aims to identify the
changes of the wet and dry patterns of weather based on daily rainfall in the
Badulla region, Sri Lanka. The study mainly looked at four aspects; trend of
precipitation and number of wet and dry days, monthly seasonal annual and
consecutive time period’s variations of transition probabilities and the wet and dry
spell durations. Mann–Kendall (M–K) test and Sen’s slope estimator are used to
investigate the trends of series and the observed transition probabilities and dry
wet spell durations were used to identify the significant differences over the given
time periods. The results indicate that there has been a significant increase in daily
rainfall, number of wet days and the seasonal transition probabilities over the 30-year period from 1992 to 2021. In order to identify the recent changes of wet dry
sequence of the region, series was divided into three consecutive periods of 10-year durations (1992–2001, 2002–2011, and 2012–2021). Results depict that the
transition probabilities for all four seasons increase significantly over three
consecutive the period. The most important thing reflected in the analysis of wet
dry spells over the different time periods is that recent decade region experienced
longer dry and wet spells compared to the past two decades and the mean dry and
wet spell durations were also showing an increasing trend over the three decades.
By resulting of this there could be an increased risk of floods in the region in the
future.
