摘要：Drought is understood as both a lack of water (i.e., adeficit compared to demand) and a temporal anomaly in one or morecomponents of the hydrological cycle. Most drought indices, however, onlyconsider the anomaly aspect, i.e., how unusual the condition is. In thispaper, we present two drought hazard indices that reflect both the deficit andanomaly aspects. The soil moisture deficit anomaly index, SMDAI, is based onthe drought severity index, DSI (Cammalleri et al., 2016), but is computed ina more straightforward way that does not require the definition of a mappingfunction. We propose a new indicator of drought hazard for water supply fromrivers, the streamflow deficit anomaly index, QDAI, which takes into accountthe surface water demand of humans and freshwater biota. Both indices arecomputed and analyzed at the global scale, with a spatial resolution ofroughly 50 km, for the period 1981–2010, using monthly time series ofvariables computed by the global water resources and the modelWaterGAP 2.2d. We found that the SMDAI and QDAI values are broadly similar tovalues of purely anomaly-based indices. However, the deficit anomaly indicesprovide more differentiated spatial and temporal patterns that help todistinguish the degree and nature of the actual drought hazard to vegetationhealth or the water supply. QDAI can be made relevant for stakeholders withdifferent perceptions about the importance of ecosystem protection, byadapting the approach for computing the amount of water that is required toremain in the river for the well-being of the river ecosystem. Both deficitanomaly indices are well suited for inclusion in local or global drought riskstudies.
