Abstract

Drought is an extreme hydroclimatic event which slowly appears over a region and intensifies its effects with time. Its impacts are less obvious than other natural disasters; however, droughts are the most important natural trigger of food shortages and famine. There is no unique definition of drought but in general terms, a drought is an exceptional lack of water compared to normal conditions and it can be classified as: meteorological (decrease of precipitation), agricultural (deficit of soil moisture), hydrological (below-normal surface and water and groundwater levels), socio-economic (related to societal drought impacts), and ecological (related to impacts in ecosystem services). Drought is a natural hazard with high economic and ecological impacts affecting millions of people each year. Severe and more widespread droughts over many land areas are expected for the 21st century due to climate change, putting additional stress on water supply systems and agricultural production. The limited capacity of response typical of developing countries might become a critical issue during this century, and therefore actions must be taken to build anticipatory adaptation and mitigation strategies to increase societal resilience to projected impacts of climate change. There has been much debate about what drought index should be used in a particular climate and for which application, resulting in several indices that quantitatively describe droughts. Among the existing indices, the World Meteorological Organisation (WMO) recommended in 2009 the use of the Standardised Precipitation Index (SPI) as the standard index to characterise and monitor meteorological droughts at different time scales. In this chapter, we evaluated the suitability of a state-of-the-art satellite-based precipitation product to characterise the meteorological droughts that have affected Chile during the last decade. This evaluation was carried out over 3 severely affected regions of Chile based on the SPI at four different temporal scales. The results showed that satellite-based datasets are a promising technology for drought monitoring in developing countries such as those in Latin America and the Caribbean. Also, the SPI at different temporal scales proved to be able to correctly identify drought characteristics in the study area. Finally, we observed an increase in the severity and duration of drought events, mostly driven by a decrease in precipitation. However, different factors such as temperature, land cover, and the vegetation water requirements might play an important role in the evaluation of the spatio-temporal characteristics of droughts. Results of this work aim at providing a cost-effective drought monitoring and early warning framework, which might be used to characterise ongoing drought events and to foster the elaboration of improved drought adaptation and mitigation policies at the regional scale.