Stochastic Model for Drought Forecasting in the Southern Taiwan Basin

Hsin-Fu Yeh,Hsin-Li Hsu

doi:10.3390/w11102041

Abstract

The global rainfall pattern has changed because of climate change, leading to numerous natural hazards, such as drought. Because drought events have led to many disasters globally, it is necessary to create an early warning system. Drought forecasting is an important step toward developing such a system. In this study, we utilized the stochastic, autoregressive integrated moving average (ARIMA) model to predict drought conditions based on the standardized precipitation index (SPI) in southern Taiwan. We employed data from 1967 to 2006 to train the model and data from 2007 to 2017 for model validation. The results showed that the coefficients of determination (R2) were over 0.80 at each station, and the root-mean-square error and mean absolute error were sufficiently low, indicating that the ARIMA model is effective and adequate for our stations. Finally, we employed the ARIMA model to forecast future drought conditions from 2019 to 2022. The results yielded relatively low SPI values in southern Taiwan in future summers. In summary, we successfully constructed an ARIMA model to forecast drought. The information in this study can act as a reference for water resource management.

Highlights

Drought is a natural phenomenon which can be classified into four categories: meteorological, hydrological, agricultural, and socioeconomic drought
We used the autoregressive integrated moving average (ARIMA) model to forecast future drought conditions based on the standardized precipitation index (SPI)
The results show that most of the residual autocorrelation function (RACF) and residual partial autocorrelation function (RPACF) values were within the confidence limit, which implies that the residuals did not exhibit a significant correlation with each other

Summary

Introduction

Drought is a natural phenomenon which can be classified into four categories: meteorological, hydrological, agricultural, and socioeconomic drought. Meteorological drought can precede and lead to the other three types. It is essentially caused by insufficient precipitation and usually results in severe disaster events. Dai [1] found that the global trends of observed annual precipitation from 1950 to 2010 showed a decline in areas such as Africa, Southeast and East Asia, Eastern Australia, and Southern Europe. These results indicate that water shortages are becoming increasingly severe, which may lead to drought.

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