Abstract:
Analysis of long-term rainfall trends provides a wealth of information on effective crop
planning and water resource management, and a better understanding of climate variability over
time. This study reveals the spatial variability of rainfall trends in Sri Lanka from 1989 to 2019 as
an indication of climate change. The exclusivity of the study is the use of rainfall data that provide
spatial variability instead of the traditional location-based approach. Henceforth, daily rainfall
data available at Climate Hazards Group InfraRed Precipitation corrected with stations (CHIRPS)
data were used for this study. The geographic information system (GIS) is used to perform spatial
data analysis on both vector and raster data. Sen’s slope estimator and the Mann–Kendall (M–K)
test are used to investigate the trends in annual and seasonal rainfall throughout all districts and
climatic zones of Sri Lanka. The most important thing reflected in this study is that there has been a
significant increase in annual rainfall from 1989 to 2019 in all climatic zones (wet, dry, intermediate,
and Semi-arid) of Sri Lanka. The maximum increase is recorded in the wet zone and the minimum
increase is in the semi-arid zone. There could be an increased risk of floods in the southern and
western provinces in the future, whereas areas in the eastern and southeastern districts may face
severe droughts during the northeastern monsoon. It is advisable to introduce effective drought and
flood management and preparedness measures to reduce the respective hazard risk levels
