Abstract
Drought is one of the most significant hazards in Sri Lanka. Status of drought in Sri Lanka was assessed using Standardized Precipitation Index (SPI) at 3, 6, and 12 months’ time scales using monthly rainfall (1970 to 2017) data of 54 weather stations. The frequency of drought events was evaluated using SPI, and trend of SPI was also detected using the Mann–Kendall (MK) test and Sen’s slope estimator. The result based on SPI identified hydrological years 1975-76, 1982-83, 1986-87, 1988-89, 2000-01, 2001-02, 2013-14, and 2016-17 as drought years for 52, 32, 35, 33, 33, 31, 31, and 31% of tested stations (54), respectively, at annual time scale. Comparison of the SPI at different time scales revealed that more drought events (SPI ≤ −1) occurred during Yala season than Maha cropping season. Considering the Thiessen polygon average rainfall, more frequent drought events occurred in the dry zone (57%) than the wet (49%) and intermediate zone (47%) at the annual time scale. SPI trend results showed greater increase in drought (59% of stations) during Yala seasons as compared to the Maha cropping season (15% of stations) in Sri Lanka.
Highlights
Drought is one of the natural disasters which can cause huge damage to agriculture and other economic and social activities of the human system, and considerable damage is caused to the ecosystem
Dry zone Oct-Mar Apr-Sep showed the Standardized Precipitation Index (SPI) values below zero, while 26 out of 54 stations showed the occurrence of extreme drought events during the end of the Yala season
SPI was calculated at different time scales, but the analysis showed that more drought events (SPI ≤ − 1) occurred at April–September time scale (Yala season) than the 3month, 6-month (Maha season), and annual SPI time scales
Summary
Drought is one of the natural disasters which can cause huge damage to agriculture and other economic and social activities of the human system, and considerable damage is caused to the ecosystem. It fundamentally occurs as a result of weather extremes that are driven by natural variability and climate change and stimulated by anthropogenic influences [1]. Based on SPI, drought can be calculated at different time scales [3], and it can be considered as an agricultural drought indicator [7]. Application of SPI to assess the drought during recent past over entire Sri Lanka has not been reported in the literature to the best of authors’ knowledge
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