Multi-scalar Indices of Drought in Intensively Farmed Regions of the Czech Republic

Abstract

Indices related to specific timescales are useful for monitoring and management of droughts. We compare the multi-scalar standardized precipitation index (SPI) and standardized precipitation-evapotranspiration index (SPEI) across the Czech Republic. The different timescales provided by the two indices can be related to different kinds of drought and their agricultural, hydrological and socio-economic impacts. Short timescales pick out variations of soil water that affect crops; water resources held in reservoirs are related to longer timescales. Data recorded since 1901 were examined to identify differences between the effects of precipitation and evapotranspiration on drought frequency. SPEI and SPI gave different indications during decades with cool dry summers (the first two decades of the twentieth century), the hottest summers (the end of the twentieth century), warm, wet springs (at the beginning of the twentieth century) and years with a big water deficit (1947, 2003, 1994, 1983 and 1933). There was similarity between the two indices for decades with warm, dry springs (1950s, 1990s and 2000s) and very long sunshine hours. The role of temperature is very evident in summer droughts that are driven by temperature anomalies, contributing to a higher potential evapotranspiration at the end of the century.