Flood analysis with the standardized precipitation index (SPI)

Abstract

The occurrence of flood spells is difficult to monitor and detect. However, there are some indices that permit to monitor hydrological and climatological conditions in river basins. The SPI (Standardized Precipitation Index) is one of those indices. Though the SPI was originally developed for drought detection and monitoring, it can also be applied to perceive wetter than normal conditions. This study pretends to characterize the relationship between the SPI and annual peak flow occurrences in the Tejo (Portugal) river basin and provide a tool for prediction of high flood risk. Results indicate that SPI satisfactorily explained the development of circumstances leading up to major peak flow events.