Analysis of SPI Spatiotemporal Variability: A Case Study for the Choró Sub-Basin, Ceará, Brazil

Abstract

This work has as objective to evaluate the spatiotemporal variability of the Standardized Index of Precipitation (SPI), in order to identify periods of water scarcity/excess in the Choró Sub-Basin in the State of Ceará. For this purpose, we worked with the historical series of rainfall data for the period from 1974 to 2018 and with the SPI on scales of 3, 6, 12, and 24 months. A pronounced inter-annual variability was observed, pointing out from 2012-2018 the highest occurrence of dry events, being these better represented, in the inter-annual scales, in intensity and duration when compared to the intras-seasonal scales. It was also found that the periods containing the most intense dry (rainy) events, presented on the scales 3, 6, and 12 months of SPI, coincided in most cases with periods of El Niño Oscilação Sul and La Niña. In short, SPI proved to be a powerful tool when quantifying dry and rainy events in the Choró Sub-Basin and can be useful in monitoring the water deficit, in short, medium, and long term time scales.

Keywords
SPI; Choró; El Niño, water scarcity