Evolution of a debris-rock slide causing a natural dam:the flash flood of Río Santa Cruz, Province of San Juan?November 12, 2005

PERUCCA, L. P.; ESPER ANGILLIERI, MARÍA YANINA

NATURAL HAZARDS (DORDRECHT)

Springer Netherlands

Año: 2009 vol. 50 p. 305 - 320

0921-030X

Between 2001 and 2005, a large debris rock slide occurred on the western slopeof the Cordillera de Santa Cruz in the southeast Andean corner of the Province of San Juan(31º40º S?70º16º W). The landslide material accumulated in a downstream gorge as anatural dam of the Santa Cruz river, forming a large-volume lake. In November 2005,probably as a result of the increasing pressure of the water volume, this natural dambreached off with a violent and unexpected flash flood. In addition to life-threateninginstances lived by some people downstream, this flood caused great economic loss to mainlocalities of the Department of Calingasta, as well as considerable damage to one of themost relevant projects of the Province, the Caracoles Hydropower Project dam on the SanJuan river. Considering the high costs of any physical remediation for a natural damlocated in this high, remote, and inaccessible mountain area with no reliable road access,the main protective measures left to be pondered are the installation of a flash-flood earlywarningsystem connected to downstream localities, along with a program of hydrologicalmonitoring at the dam-forming area and annual satellital monitoring to verify the evolutionof accumulated mass movements.