Abstract:
The occurrence of extreme rainfall events with higher intensity is becoming a common
phenomenon in most parts of the world and it is an exigent challenge to adapt the
changing climate. The World Meteorological Organization defines few indicators to
calculate the intensity of rainfall extremes and it is of timely importance to identify the
trends of these dry extremes as a country. This study mainly focused on ascertaining
the spatial trends of intensity of rainfall extremes over Sri Lanka for the period of 1981
to 2010. Extremes are identified using daily rainfall data using RClimDex 1.0 package.
This study applies five intensity indicators including Total Wet Day Precipitation
(PRCPTOT), Very Wet days (R95p), Extremely Wet days (R99p), Maximum 1-day
Precipitation (Rxlday) and Maximum 5-day Precipitation (Rx5day). Non-parametric
Mann Kendall test is used to detect the trends and their significance. All the stations
record an increasing trend in case of PRCPTOT excluding Nuwara Eliya. Among them,
Colombo, Rathmalana, Anuradhapura, Badulla, Baticaloa and Trincomalee show a
significant increasing trend. Trend of R95p seems significant and increasing in Badulla
and Baticaloa whereas Nuwara Eliya and Rathnapura show a decreasing trend although
the trend is not significant. Only Katunayaka and Rathmalana show significant
increasing trends in R99p. The trends in Puttalam, Nuwara Eliya and Rathnapura are
not significant decreasing trends. Rathmalana depicts significant increasing trend in
case of Rxlday. Rx5 day predicates significant increasing trends in Batticalo, Colombo,
Hambanthota, Rathmalana and Trincomalee. In conclusion, Ratnapura and Nuwara
Eliya are highlighting with decreasing trends in almost all the indicators. And a higher
influence from the extremes can be seen in Western Province including Colombo,
Ratmalana signing a shift of the adverse impacts towards Western Province from
Ratnapura and subordinates. On the other hand Baticaloa and Trincomalee are also
highly vulnerable for adverse impacts caused by the intensified rainfall. These spatial
trends should be focused in decision making and planning related to disaster
management and implementing strategies for climate change adaptationj-within the
country.
