Analysis of the 2010-2017 Megadrought in Chile Using the Standarized Precipitation Index

Droughts are a recurring and temporary extreme climate events of below-normal precipitation, which caused more than 50% of the deaths associated with natural disasters in the 20th century and, after floods, the natural disaster that affected the greatest number of people. Since 2010, a large part of Chile is in an ongoing period of drought, causing impacts on the population and water resources systems. Therefore, it is necessary to conduct drought behavior studies in Chile through characterization with indexes and focused to identify appropriate measures to mitigate the effects of a drought event, to face a dry and warm future regional climate scenario.

Thus, the objective of this study is to analyze the dry period 2010-2017, known as "megadrought", that affected Central-Southern Chile using the Standardized Precipitation Index (SPI), which is solely based on precipitation and widely used to monitoring meteorological droughts.

The methodology applied is based on the study of the SPI and its characteristics, and its subsequent calculation at 12 months time scale in the area between the regions of Valparaíso and Magallanes in Chile (32°-56°S). Characteristics of duration, intensity and magnitude of drought were obtained through tables and kriging-based spatial interpolation maps. Additionally, a comparison with another extreme drought event was made.

The results indicate that 99.4% of stations were affected by megadrought, with a moderate intensity classification and variable duration and magnitude. Likewise, it mainly concentrated in the years of 2014 and 2016, with the highest values of duration, intensity and magnitude. In spatial terms, the highest values of duration and magnitude were obtained in the region of Biobío (37°S) during 2010-2017 with 33 months of dry condition, moderate intensity classification and -44.8 magnitude. Finally, the megadrought magnitude was 33% greater than 1998-1999 drought event in Chile, mostly because of its long duration, besides of the greater area of affectation.