Preprints
https://doi.org/10.5194/hess-2017-512
https://doi.org/10.5194/hess-2017-512
17 Aug 2017
 | 17 Aug 2017
Status: this preprint was under review for the journal HESS. A revision for further review has not been submitted.

Frequently used drought indices reflect different drought conditions on global scale

Niko Wanders, Anne F. Van Loon, and Henny A. J. Van Lanen

Abstract. Drought is an abnormal and prolonged deficit in available water. Possible drought impacts are crop losses, famine, fatalities, power blackouts and degraded ecosystems. These severe socio-economic and environmental impacts show the need to carefully monitor drought conditions using a suitable index. Our objective is to provide an intercomparison of frequently used physical drought indices to show to which degree they are interchangeable for monitoring drought in precipitation, soil moisture, groundwater and streamflow. Physical indices are commonly introduced to predict drought impacts, because appropriate drought impact indices are still missing. Correlations (R) between frequently used indices for different drought types were calculated at the global scale. We have made the index timeseries available to the community for future studies. Precipitation drought indices show low to intermediate correlations (ranging from R = 0.1 to 0.75), soil moisture drought indices show an even lower similarity (R = 0.25). Indices for streamflow drought show the highest correlation (R = 0.5 to 0.95). Additionally, meteorological drought indices do not capture the soil moisture drought correctly (R = 0.0 to 0.6) nor streamflow drought (R = 0.0 to 0.7). These findings have implications for drought monitoring systems: (i) for each drought type, a different index should carefully be identified; (ii) drought indices that are designed to monitor the same drought type show large discrepancies in their anomalies and hence drought detection; (iii) there is no single superior physical drought index that is capable of accurately capturing the diverse set of drought impacts in all parts of the hydrological cycle.

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Niko Wanders, Anne F. Van Loon, and Henny A. J. Van Lanen
 
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Niko Wanders, Anne F. Van Loon, and Henny A. J. Van Lanen
Niko Wanders, Anne F. Van Loon, and Henny A. J. Van Lanen

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Latest update: 18 May 2024
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Short summary
This paper investigates the similarities between frequently used drought indicators and how they should be used for global drought monitoring. We find that drought indicators that should monitor drought in the same hydrological domain show high discrepancy in their anomalies and thus drought detection. This shows that the current ways of monitoring drought events is not sufficient to fully capture the complexity of drought events and monitor the socio-economic impact of these large-scale events.