Abstract
The Standardized Precipitation Evapotranspiration Index (SPEI) is widely used for climatological and hydrological studies, in which the estimation of potential evapotranspiration (PET) is of great importance. As many different models exist in estimating PET, the question that arises is in which way the selection of the PET model affects the calculated SPEI and the drought assessment. This study, on the basis of evaluating drought conditions over the Hexi Inland River Basin in China with long-term climate data of 18 stations by using SPEI, compared three types and eight kinds different PET models with respect to their sensitivity to the calculation of SPEI, and to drought events and drought characteristics. The results showed that the study area experienced a drying trend over the past 56 years, and the extreme drought events occurred more frequently after 2000 as a whole. All the investigated PET models were sensitive to the estimation of SPEI and to the drought assessment. When considering the alternatives of the Thornthwaite model in the calculation of SPEI for drought identification, the Blaney–Criddle equation among the temperature-based models and the Makkink equation among the radiation-based models are recommended due to the comparable results in determining the drought trends, drought events, and drought characteristics.
Highlights
Drought is one of the major natural disasters in human history, and its catastrophic consequences are still innumerable even with current highly developed science and technology
The drought conditions were determined according to the criteria mentioned in Section 2.2, that when the Standardized Precipitation Evapotranspiration Index (SPEI) value for a particular time period fell less than or equal to −0.5, it was regarded as a drought event
Comparing the correlation coefficients for each station, we found that SPEIBC, SPEISzász, and SPEI values from different potential evapotranspiration (PET) models were compared by using the Pearson correlation
Summary
Drought is one of the major natural disasters in human history, and its catastrophic consequences are still innumerable even with current highly developed science and technology. Drought is usually divided into these categories: Meteorological drought, hydrological drought, agricultural drought, and socio-economic drought [1,2,3]. Among these types, meteorological drought is usually the basis for the other three types of droughts. Timely meteorological drought monitoring is essential for early warning and risk management of water resources and agricultural production [4]. Drought assessment is of great importance for water resource planning and management [5], and it can help governments to develop a more proactive approach to drought management and planning [6], especially for regions prone to drought
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