The impracticality of a universal drought definition
This paper demonstrates the impracticality of a comprehensive mathematical definition of the term ‘drought’ which formalises the general qualitative definition that drought is ‘a deficit of water relative to normal conditions’. Starting from the local water balance, it is shown that a universal description of drought requires reference to water supply, demand and management. The influence of human intervention through water management is shown to be intrinsic to the definition of drought in the universal sense and can only be eliminated in the case of purely meteorological drought. The state of drought is shown to be predicated on the existence of climatological norms for a multitude of process-specific terms. In general, these norms are either difficult to obtain or even non-existent in the non-stationary context of climate change. Such climatological considerations, in conjunction with the difficulty of quantifying human influence, lead to the conclusion that we cannot reasonably expect the existence of any workable generalised objective definition of drought.
KeywordsDrought Severity Standardise Precipitation Index Drought Index Meteorological Drought Drought Impact
The author thanks Deloitte for supporting the Deloitte-Walker Institute Research Fellowship at the University of Reading.
- European Commission (2007) Second interim report on water scarcity and droughts. European Commission, Brussels, p 93Google Scholar
- Heim RR Jr (2002) A review of twentieth-century drought indices used in the United States. Bull Amer Meteor Soc 83(8):1149–1165Google Scholar
- Mawdsley J, Petts G, Walker S (1994) Assessment of drought severity. British Hydrological Society, London, p 30Google Scholar
- Palmer WC (1965) Meteorological drought. Research paper no. 45. US Weather Bureau, Washington, p 58Google Scholar
- Sheffield J, Wood EF (2011). Drought: past problems and future scenarios. Earthscan, London, p 210Google Scholar
- Smakhtin VU, Hughes DA (2004) Review, automated estimation and analyses of drought indices in South Asia. Number working paper no. 83—drought series paper no. 1. IWMI, ColomboGoogle Scholar
- Steila D (1987) The encyclopedia of climatology, chap Drought. van Nostrand Reinhold, pp 388395; p 1002Google Scholar
- Svoboda M, LeComte D, Hayes M, Heim R, Gleason K, Angel J, Rippey B, Tinker R, Palecki M, Stooksbury D, Miskus D, Stephens S (2002) The drought monitor. Bull Am Meteor Soc 83(8):1181–1190Google Scholar
- Tallaksen LM, van Lanen HAJ (2004) Hydrological drought: processes and estimation methods for streamflow and groundwater. Developments in water science. Elsevier, Amsterdam, ISBN 9780444517678, p 579Google Scholar
- van Lanen HAJ, Kundzewicz ZW, Tallaksen LM, Hisdal H, Fendeková M, Prudhomme C (2009) Indices for different types of droughts and floods at different scales. WATCH Tech Rep 11:20Google Scholar
- World Meteorological Organization (1992) International meteorological vocabulary, 2nd edn. Publication no. 182. World Meteorological Organization (WMO), Geneva, p 784Google Scholar