Recent rainfall trend over Sri Lanka (1987–2017)

Abstract

Rainfall trend analysis provides useful information for effective planning, and management of water resources, and gives an insight into climate change of a region. This study investigates trends in annual and seasonal rainfall over Sri Lanka using an Innovative Trend Analysis (ITA) and Mann–Kendall (MK) test with Sen's slope estimator. The MK test showed increasing trends in annual rainfall at 24 stations (65%) with five stations showing significant increasing trend. Annual rainfall at 13 locations (35%) showed decreasing trend, but none were significant (p < .05). ITA results for annual rainfall showed increasing trend at 67% stations while 33% stations showed decreasing trend. MK test results for seasonal rainfall indicated increasing trend at 76, 51, 32, and 86% of stations during First Inter‐Monsoon (FIM), Second Inter‐Monsoon (SIM), South West Monsoon (SWM), and North East Monsoon (NEM) seasons, respectively. Seasonal analysis of rainfall trend using ITA method showed increasing trend in 81, 70, 32, and 65% stations during FIM, SIM, SWM, and NEM, respectively. ITA and MK tests exhibited similar trend results for 80% of the stations. Moreover, Spearman's rho correlation coefficient between ITA and MK test trends showed significant (p < .05) positive correlation. In general, eastern, south eastern, north and north central regions of the country showed increasing rainfall trend over the last 31 years (1987–2017) while western, part of north western and central part of the country indicated a decreasing rainfall trend during the same period.

SPI-Based Spatiotemporal Drought over Sri Lanka

“…However, during Yala season, most parts of the country are getting dryer except far north and southwestern part. A similar trend was observed for the rainfall trend analysis for Yala and Maha season during the 1987-2017 period using MK test [35].…”

“…Most of these stations showing wetting tendencies are located in dry zone of the country except Chesterford, Geekiyanakanda, and Matale. Nisansala et al [35] analyzing the rainfall trend at 37 stations during the recent 31 years (1987-2017) showed an increasing annual rainfall trend over the country and further they showed a significant increase at four stations located in the dry zone, but only one station in the wet zone.…”

“…Annual rainfall of each of the 54 stations was subjected to SPI analysis, and we identified nine hydrological years 1975-76, 1982-83, 1986-87, 1988-89, 2000-01, 2001-02, 2003-04, 2013-14, and 2016-17 as drought years (SPI < − 1) for 52, 32,35,33,33,31,30,31, and 31% of tested stations, respectively (Figure 2). Among them, the 1975-76 hydrological year showed the maximum number of drought events in different stations (52% of stations) than other years ( Figure 2).…”

Spatial Variability of Rainfall Trends in Sri Lanka from 1989 to 2019 as an Indication of Climate Change

“…In addition, some studies have shown that urban temperature is rising in Sri Lanka [20]. Analysis of rainfall trends has become a research field that has attracted great interest and enthusiasm in recent times [21]. However, as the global or regional scale declines to the national or sub-national level, further localized variations can be observed [22].…”

“…As an example, a large number of studies on rainfall trends in Sri Lanka have been conducted over the past three decades and identified different localized variabilities in the country [21,[38][39][40][41][42]. A recent study [21] showed that the eastern, southeastern, northern, and north-central parts of Sri Lanka have been experiencing an increase in rainfall over the past 31 years (1987-2017), and that there has been a decrease in the trend of rainfall in the western, northwestern, and central parts of the country.…”