Assessing changes in drought and wetness episodes in drainage basins using the Standardized Precipitation Index.

The temporal and spatial variability of precipitation might affect in a different way the society, the environment and the economy at the local and regional scales, depending on specific conditions. This study focuses on using the Standardized Precipitation Index (SPI) to identifying abnormal dry and wet periods and to understanding its spatial patterns at the drainage basin scale, for selected basins in mainland Portugal (1941-2012); this index might be useful in hydrological studies, in particular in basins missing detailed information on precipitation. Overall, SPI shows changes in the extent of dry and wet extremes throughout various time scales that depend on the season and geographical location within mainland Portugal. [ABSTRACT FROM AUTHOR]