Drought detection in Java Island based on Standardized Precipitation and Evapotranspiration Index (SPEI)

Suroso Suroso,Dede Nadhilah,Ardiansyah Ardiansyah,Edvin Aldrian

doi:10.2166/wcc.2021.022

Abstract

Abstract This study reports a drought analysis which was carried out using the Standardized Precipitation and Evapotranspiration Index (SPEI) to determine the spatial and temporal level of drought risk in Java, Indonesia. Apart from using the SPEI, this study also used the SPI (Standardized Precipitation Index) as a comparison in detecting drought and also validated with historical drought occurrences. Temporal variations of SPI and SPEI values were discussed by considering different timescales (monthly to yearly). Pearson's correlations between both drought indices were calculated to see how similar both indices were. Also, the Kolmogorov–Smirnov tests were used for the similarity test of two kinds of distributions. The results obtained from this analysis showed that the correlation coefficient between the SPI and SPEI models was relatively high on a monthly scale and consistently increased along with the increase of temporal scales but had a decreasing trend during the dry season. However, the SPI detected drought severity with an excessively high estimate in comparison with the SPEI. Greater spatial extents of drought estimation were also generated by SPI followed by SPEI in comparison to factual drought occurrences. As a consequence, SPEI becomes more moderate and SPI as a conservative approach for estimating drought events.

Highlights

Drought is a natural phenomenon that occurs as a result of a high rainfall deficit (Wang & Asefa )
Standardized Precipitation and Evapotranspiration Index (SPEI) is a standardized variable, and it can be compared with other SPEI values over time and space
Drought occurs when the SPEI value is consistently negative and reaches drought intensity with an SPEI value of À1 or less, and the drought will end if the SPEI value becomes positive

Summary

Introduction

Drought is a natural phenomenon that occurs as a result of a high rainfall deficit (Wang & Asefa ). This later influences the agricultural sector in Indonesia directly. It was reported by Indonesian Statistics (BPS) that the potential financial loss due to drought in agriculture is estimated at three trillion rupiahs per year (BPS ). Throughout 2019, Indonesia’s total losses due to forest and land fires reached US$ 5.2 million (Rp. 72.95 trillion), which was equivalent to 0.5% of Indonesia’s Gross Domestic Product (GDP) (World Bank ). Having the potential to cause severe impacts, drought has become a disaster that has received serious attention at both national and international levels, since it greatly affects people’s activities in various sectors of life (Stampfli et al )

Methods

Results

Conclusion