Performance of Drought Indices for Ecological, Agricultural, and Hydrological Applications

Abstract

Abstract:In this study we provide a global assessment of the performance of different drought indices for monitoring drought impacts on several hydrological, agricultural and ecological response variables. For this purpose, we compare the performance of several drought indices (the Standardized Precipitation Index, SPI; four versions of the Palmer Drought Severity Index, PDSI; and the Standardized Precipitation Evapotranspiration Index, SPEI) to predict changes in streamflow, soil moisture, forest growth and crop yield. We found a superior capability of the SPEI and the SPI drought indices, which are calculated on different time-scales, than the Palmer indices to capture the drought impacts on the aforementioned hydrological, agricultural and ecological variables. We detected small differences in the comparative performance of the SPI and the SPEI indices, but the SPEI was the drought index that best captured the responses of the assessed variables to drought in summer, the season in which more drought-related impacts are recorded and in which drought monitoring is critical. Hence, the SPEI index shows improved capability to identify drought impacts as compared with the SPI one. In conclusion, it seems reasonable to recommend the use of the SPEI if the responses of the variables of interest to drought are not known a priori.

Drought Trends in the Iberian Peninsula over the Last 112 Years

“…In the last decades, the severity of droughts in the IP has increased, together with an increased tendency for dryness and decrease of vegetation cover, due to the higher atmospheric evaporative demand [28,37]. These agree with the findings of Greve et al [38] that identified the Southwest of the IP as one hot spot of the pattern "dry gets drier."…”

Multiscale evaluation of the Standardized Precipitation Index as a groundwater drought indicator

“…SPEI can account for the influence of temperature variability and thus it is better suited than the SPI for drought studies under global warming conditions. In regions with high precipitation variability (e.g., humid areas), both the SPI and SPEI are expected to generally exhibit a similar behavior, albeit with slight differences among each other during a specific calendar month and time period (Vicente-Serrano et al, 2012).…”

“…While there are many studies that have focused on analyzing the propagation of meteorological droughts through the hydrologic systems for improved process understanding of the evolution of hydrologic (groundwater) droughts (e.g., Eltahir and Yeh, 1999;Peters et al, 2003Peters et al, , 2005Peters et al, , 2006Tallaksen et al, 2006Tallaksen et al, , 2009Weider and Boutt, 2010;Vicente-Serrano et al, 2012;Bloomfield and Marchant, 2013;Haslinger et al, 2014;López-Moreno et al, 2013;Van Loon et al, 2014), there is still a lack of comprehensive observation-based studies to verify whether hydrological drought proxies, like precipitation-based indices (SPI) and gridded data products, are suitable for groundwater drought monitoring at regional to local scales relevant for water management. In recent years there have been some efforts to analyze the relationship between meteorological and groundwater-based drought indices (Bloomfield and Marchant, 2013;Folland et al, 2015;Bachmair et al, 2015).…”

Inadequacy of the gamma distribution to calculate the Standardized Precipitation Index

“…Thus, the SPI is able to simultaneously describe wet conditions at a given timescale and dry conditions at other timescale (Türkeş & Tatli, 2009). However, the time responses to drought of different systems such as water reservoirs and/or soil moisture are frequently not known (Vicente-Serrano et al, 2012). Therefore, for each particular application and region a detailed study should be carried out to relate the different SPI values (calculated at different timescales) to the variable of interest (e.g.…”