Research the drought characteristics of Ninh Thuan province through the Rainfall Anomaly Index (RAI), Standardized Precipitation Index (SPI), and the Moisture Index (MI)

Abstract

This article studies the drought characteristics of the Ninh Thuan province in the past through meteorological data for the period 1986-2016. The study used three main indicators to study drought, namely, the Rainfall Anomaly Index (RAI), Standardized Precipitation Index (SPI), and Moisture Index (MI). Besides, the study also used non-parametric analysis to study trends and Spearman's rho to study the correlation between the indexes. The results of the study showed the occurrence of drought in the period 1986-2016 with different developments and frequencies, in which the period 1986-97 drought appeared continuously. According to RAI's drought index, the drought occurs 15 times with a frequency of severe drought of 12.5% and mild drought of 34.4%. SPI's drought index shows the drought happened 26 times with a severe drought in 1988. Drought occurred 31 times during the study period, 77% of the time, and the severe drought only occurred in 1998, according to the drought index MI. Additionally, the study also identified the trend of changes in drought indicators in the future and showed a trend of reducing drought in Ninh Thuan. The trend results show an average annual increase in RAI and MI of 0.01 and SPI of 0.08. To consolidate and evaluate the significance, the study also evaluated the correlation between indicators, and the results met the requirements with a value of > 0.84. The three indexes have Cronbach's Alpha reliability is 0.78, in which, the SPI index correlates most strongly with RAI and MI at 0.92 and 0.94, respectively. This result will help local authorities and policymakers have more methods to study future droughts and develop solutions to socio-economic development in Ninh Thuạn in the context of drought.