Soil moisture and streamflow deficit anomaly index: an approach to quantify drought hazards by combining deficit and anomaly

Abstract. Drought is understood as both a lack of water (i.e., deficit compared to demand) and temporal anomaly in one or more components the hydrological cycle. Most drought indices, however, only consider aspect, i.e., how unusual condition is. In this paper, we present two hazard indices that reflect aspects. The soil moisture index, SMDAI, based on severity DSI (Cammalleri et al., 2016), but computed straightforward way does not require definition mapping function. We propose new indicator for supply from rivers, streamflow QDAI, which takes into account surface demand humans freshwater biota. Both are analyzed at global scale, with spatial resolution roughly 50 km, period 1981–2010, using monthly time series variables by resources model WaterGAP 2.2d. found SMDAI QDAI values broadly similar purely anomaly-based indices. However, provide differentiated patterns help distinguish degree nature actual vegetation health supply. can be made relevant stakeholders different perceptions about importance ecosystem protection, adapting approach computing amount required remain river well-being ecosystem. well suited inclusion local risk studies.