The great droughts of 1924-25 and 1968-69 in the argentinean central andes. Impacts and responses

PRIETO M. R.; ARANEO D.; VILLALBA R.

Valdivia

Simposio; II International Symposium: “Reconstructing Climate Variations in South America and the Antarctic Peninsula over the last 2000 years”; 2010

The increased frequency of extreme droughts in the Andes Cordillera over the past 100 years has been concurrent with a large increase in regional population, and consequently, with a greater demand of water for domestic use, irrigation and energy production on both sides of the Central Andes. In addition, the extraordinary recession of glaciers over this period has also reduced the ice-mass capacity for regulation of Andean streamflows in times of shortage. The present work studies the extreme drought events of 1924-25 and 1968-69 in the Argentinean Central Andes using historical documentation, tree rings and meteorological records. This case study demonstrates the significant impacts of water shortages during the spring-summer period for a province such as Mendoza, Argentina, in which agricultural, economic and daily life depends on the flow of rivers originating from the eastern flanks of the Andes Cordillera. Although both drought events were relatively similar in magnitude, the socio-economic scenarios during these two dry events were significantly different: A small population largely distributed across rural areas in 1924-25 contrast with a larger (more than double), urban-concentrated population in 1968-69. Thus, whereas the social unrest, as reported by the local newspapers, was mainly associated with the lack of water for irrigation during the 1924-25 drought, the reduction in hydro-power genera- tion for the urban populations was the major concern during the dry 1968-69 event. The results of this study could be useful in establishing guidelines for political actions to prevent or at least, alleviate the effects of similar future droughts. The significant population increase in Mendoza since the 1968-69 drought and the present infrastructure problems related to usage of the water resource would further exacerbate these drought detrimental effects.