Abstract
Drought monitoring, including its severity, spatial, and duration is essential to enhance resilience towards drought, particularly for overcoming drought risk management and mitigation plan. The present study has an objective to examine the suitability of the Standardized Precipitation Index (SPI) and Percent of Normal Index (PN) on assessing drought event by analyzing their relationship with the Southern Oscillation Index (SOI). The monthly rainfall data over twenty years of the observation period were used as a basis for data input in the drought index calculation. The statistical association analyses, included the Pearson Correlation (r), Kendal tau (τ), and Spearman rho (rs) used to assess the relationship between the monthly drought indexes and SOI. The present study confirmed that the SPI showed a more consistent and regular pattern relationship with SOI basis which was indicated by a moderately high determination coefficient (R2) of 0.74 and the magnitude of r, τ, and rs that were of 0.861, 0.736, and 0.896, respectively. Accordingly, the SPI showed better compatibility than the PN for estimating drought characteristics. The study also revealed that the SOI data could be used as a variable to determine the reliability of drought index results.
Highlights
In the recent decade, climate change phenomena have been a main issue in the worldwide since its impact on many sectors of economic and social, including water resources sector as the foundation of civilization – agriculture [1]
There are still a few studies concerning the use of the Southern Oscillation Index (SOI) characteristic to examine the suitability of the method of drought index
To know further regarding the suitability level of the practicability of the two drought index methods for assessing drought event in the study area, the drought index resulted from the Standardized Precipitation Index (SPI) and Percent of Normal Index (PN) was compared with the Southern Oscillation Index (SOI) over the period 2000 – 2019 obtained from the website of the Australian Government, Bureau of Meteorology
Summary
Climate change phenomena have been a main issue in the worldwide since its impact on many sectors of economic and social, including water resources sector as the foundation of civilization – agriculture [1]. The study concerning the comparison between the Standardized Precipitation Index (SPI) and Percent of Normal Index (PN), in an agrarian, semi-arid, and drought susceptible regions is still rarely carried out. There are still a few studies concerning the use of the Southern Oscillation Index (SOI) characteristic to examine the suitability of the method of drought index. The present study has an aim to examine the application of two meteorological drought index, i.e the Standardized Precipitation Index (SPI) and Percent of Normal Index (PN), and subsequently determine their suitability by assessing their relationship with the Southern Oscillation Index (SOI) in the Gending River basin. The paper is ended with the conclusions describing which drought method reliable to assess drought characteristics in the study area (Section 4)
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