Spatio-temporal assessment of meteorological drought in Puerto Rico between 1950 and 2019

The phenomenon of drought is one of the most dangerous for small islands because of its impacts on freshwater availability. Thus, in this study was investigated the spatio-temporal evolution of meteorological drought that affected the main island of Puerto Rico in the period 1950 – 2019. To do it, the Standardised Precipitation-Evapotranspiration Index (SPEI) using monthly values of minimum and maximum temperature, and of precipitation derived from Daymet Version 4 daily data at a 1 km x 1 km spatial resolution was used. At 1-month temporal scale the SPEI shows great temporal variability, the occurrence of 85 meteorological drought episodes, but a clear tendency towards wetting, principally in the last years of the study period. The spatial analysis also revealed that major affectation by moderate drought conditions has occurred across the half west and south of the island, by severe drought also in the half west of the island as well as along the eastern coast, and finally, the extreme drought conditions, which have been less frequent has principally affected the northeast of the country. However, a trend analysis of the area affected by moderate, severe, and extreme drought conditions revealed a tendency to decrease, which is reflected by the prevalence of positive spatial trends of the SPEI1 across the country.