Spatial and Temporal Trends in Rainfall in the Dry and Wet Seasons in Sri Lanka from 1994 to 2020

Abstract

Climate change is a global crisis impacting the entire world. In July 2023, the severity of this crisis became clearly evident, as it marked the hottest month ever recorded in history. Sri Lanka in particular, faces a critical situation, with temperatures soaring to unprecedented levels, surpassing the global average by about 1.8 °C per decade. These changes have important implications for the country’s food security, particularly during the two main cultivating seasons, Dry (March-September) and Wet (October-February), especially in terms of crop production. This study employed the Mann-Kendall Trend test, Sen’s slope estimator, Coefficient of Variations (CV), and Z statistics to examine the trends in rainfall in the Dry and Wet seasons using data from 13 rain gauge stations encompassing all three climatic zones (Wet, Intermediate and Dry) from 1994 to 2020. Notably, In the Dry season, two rain gauge stations Anuradhapura and Mahailluppallama in the Dry Zone (DZ), exhibited a significant increasing trend, and a majority of the stations showed an increasing trend potentially linked to the growing occurrence of extreme rainfall events. Conversely, none of the rain gauge stations showed a notable trend, but a majority of the stations showed a decreasing trend in the Wet seasons. While a North- South gradient is discernible, the diversity of trends observed in different regions highlighted the need for localized climate studies bolstered by cutting-edge climate models that peer into Sri Lanka’s climate future. Such knowledge would better support climate change adaptation and mitigation efforts, securing a sustainable future for Sri Lanka.