A preliminary assessment of meteorological and hydrological drought indicators for application to catchments across the UK

Standardised indicators for drought are widely used for drought monitoring and early warning, but have found only limited application in the UK. Important questions remain concerning the choice of appropriate probability distributions for their application. Here, we present a first pass appraisal of the Standardized Precipitation Index (SPI) and Stand-ardized Flow Index (SFI) for application to UK catchments, using a diverse set of 121 near-natural catchments. In general terms, the Pearson type 3 distribution is most appropri-ate for precipitation and the Generalised Extreme Value distribution for flow. We also ex-plore relationships between SPI and SFI accumulation periods across a range of catch-ments, using Base Flow Index (BFI) as a surrogate for storage. Unsurprisingly, longer ac-cumulation periods are more appropriate for high-storage catchments, but the relationship with BFI is not straightforward, suggesting more work is needed using a wider range of catchment descriptors.