A Drought Index: The Standardized Precipitation Evapotranspiration Irrigation Index

Abstract

Drought has had an increasingly serious impact on humans with global climate change. The drought index is an important indicator used to understand and assess different types of droughts. At present, many drought indexes do not sufficiently consider human activity factors. This study presents a modified drought index and the standardized precipitation evapotranspiration irrigation index (SPEII), considering the human activity of irrigation that is based on the theory of the standardized precipitation evapotranspiration index (SPEI). This study aims to compare the modified drought index (SPEII) and ·SPEI and self-calibrating Palmer drought severity index (scPDSI) in the major crop-producing areas and use SPEII to evaluate the possible future drought characteristics based on CMIP5 Model. The Pearson correlation coefficient was used to assess the relevance between drought indexes (SPEII, SPEI, and scPDSI) and vegetation dynamics. The normalized difference vegetation index (NDVI) was used to represent the vegetation dynamics change. The results showed that SPEII had better performance than the SPEI and scPDSI in monitoring cropland vegetation drought, especially in cropland areas with high irrigation. The winter wheat growth period of the SPEII had better performance than that of summer maize in croplands with higher irrigation levels on the North China Plain (NCP) and Loess Plateau (LP). In general, future drought on the NCP and LP showed small changes compared with the base period (2001–2007). The drought intensity of the winter wheat growth period showed an increasing and steady trend in 2020–2080 under the representative concentration pathway (RCP) 4.5 scenario on the NCP and LP; additionally, the severe drought frequency in the central LP showed an increasing trend between 2020 and 2059. Therefore, the SPEII can be more suitable for analyzing and evaluating drought conditions in a large area of irrigated cropland and to assess the impacts of climate change on vegetation.

Investigate the Spatiotemporal Evolution of Drought and Its Interaction with Atmospheric Circulation in the Yellow River Middle Basin

“…Numerous researchers have introduced a variety of drought indicators aimed at effectively tracking drought pa erns. Among these indicators, the most commonly employed ones include the Palmer Drought Severity Index (PDSI) [16], the Standardized Precipitation Index (SPI) [17], the Reconnaissance Drought Index (RDI) [18], the Standardized Precipitation Evapotranspiration Index (SPEI) [19], the Standardized Precipitation Temperature Index (SPTI) [20], the Integrated Drought Index (IDI) [21], and the Standardized Precipitation Evapotranspiration Irrigation Index (SPEII) [22]. Notably, the PDSI, SPI, and SPEI stand out as drought studies' most widely adopted indicators.…”