Abstract
During the period 2010–2015, the semi-arid Central Andes in Argentina (CAA) experienced one of the most severe and long-lasting hydrological droughts on record. Since the snowmelt is the most important source of water, the reduced snowfall over the mountains propagated the drought signal through the streamflows in the adjacent foothills east of the Andes ranges. Motivated by the widespread impacts on the socio-economic activities in the region, this study aims to characterize the recent hydrological drought in terms of streamflow deficits. Based on streamflow data from 20 basins, we used the standardized streamflow index (SSI) to characterize hydrological droughts during the period 1971–2016. We found that the regional extent of the 2010–2015 hydrological drought was limited to the basins located north of 38° S, with mean duration of 67 months and maximum drought severity exhibiting a heterogeneous pattern in terms of spatial distribution and time of occurrence. The drought event reached extreme conditions in 14 of the 15 basins in the CAA, being record-breaking drought in six of the basins. This condition was likely driven by a cooling in the tropical Pacific Ocean resembling La Niña conditions, which generated a decrease in snowfall over the Andes due to suppressed frontal activity.
Highlights
Given the recent changes in the frequency, duration and intensity of droughts, a comprehensive understanding of water scarcity is needed at different temporal and spatial scales
Hydrological drought was assessed in terms of streamflow variations, using the standardized streamflow index (SSI, [29]), widely used indexof conceived as anvariations, extension from thethe standardized
Snow drought is not a new hazard across the Central Andes in Argentina (CAA), we just need to look at the snowpack records from the years 1968 or 1996 to verify that is a recurrent phenomenon commonly linked to meteorological drought conditions over central Chile
Summary
Given the recent changes in the frequency, duration and intensity of droughts, a comprehensive understanding of water scarcity is needed at different temporal and spatial scales. This requirement is pressing given the marked increase in demand of water for agriculture, energy production, industry and human consumption. In South America, an uninterrupted rainfall decline was recorded in Central Chile from 2010 to date [5,6], while the semi-arid northeastern Brazil has experienced since 2010 the longest and most intense drought in decades [7], with more than 10 million people affected and large losses on rainfed agriculture [8]. A period of unprecedented rainfall shortage, called the “Millennium Drought”, has been registered in Australia [9], at the time that 2015 was the year with the lowest national annual rainfalls since records started in 1904 in South Africa [10]
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