Abstract ID: 3.13382 | Accepted as Talk | Talk | TBA | TBA

The Mediterranean basin is one of the areas most exposed to drought and paradigmaticly highly dependent on water resources in its socioeconomic development. Its climate is naturally characterized by a high variability that is being exacerbated by the current climate warming situation. In this sense, future projections agree that the frequency and severity of these extreme events will increase. In addition, the Mediterranean basin is delimitated by considerable mountain ranges close to the sea that draw different-sized catchments in which the presence of snow constitutes a significant proportion of their total water resources. Hence, it seems obvious that snow dynamics need to be considered when analyzing droughts. However, drought indexes, which are the most extended tool to characterize droughts, do not explicitly account for snow. This work aims to directly include snow dynamics in defining drought over these catchments. To achieve this, we introduce the concept of snow drought using snowfall as the target variable to propose a new standardized drought index, Standardized Snowfall Index (SSNI), in the whole region. The index definition is based on the methodology already proposed when defining other drought indexes, such as the Standardized Precipitation Index (SPI) or the Standardized Streamflow Index (SSI), evaluating different candidate distributions and aggregation times. HydroGFD3 bias-adjusted reanalysis data for precipitation and temperature for the last five decades are used in the study. The new index was evaluated in 18 pilot catchments along the region. The results show that the candidate distribution selected differed depending on the location and aggregation time. This new index helps better quantify the effect of a snow deficit in the meteorological drought definition and its implication throughout the drought propagation cascade over a region highly exposed to drought events.