Stability analysis and morphometric characterization of palaeo-lakes of the Benjamin Matienzo Basin- Las Cuevas River, Argentina

MOREIRAS S.M., LAURO C., Y MASTRANTONIO L.E.

NATURAL HAZARDS (DORDRECHT)

SPRINGER

Lugar: Berlin; Año: 2012 vol. 62 p. 593 - 611

0921-030X

Natural dams are caused by the blockage of streams as a result of the suddenarrival of detritus material during a glacial surge advance or fast slope collapse threateningdownstream populations. Nevertheless, origin, morphological characteristics and stabilityof dammed lakes are frequently ignored. Six impounded palaeo-lakes were geomorphologicallystudied in the Benjamin Matienzo gully (32140 S–70020 W), denominated, fromnorth to south: Goyete, Negro, Casa de Piedra, Lagunita, Susanita and Matienzo. Wedetermined the origin, morphometric parameters, stability index and rate of streamflowrupture for these dammed ancient lakes in order to shed light on the potential outburst floodhazard in this Andean mountain region. According to our findings, we concluded thatpalaeo-lakes would have had a short life as they turned out to be unstable, except for theGoyete Lake, matching with the lack of fine lacustrine sediments in all river blockages. Wealso estimated the maximum peak discharge of a probable outburst flow generated during adrastic collapse of these dams. Obtained values range between 22 and 151 m3/s beingnotably higher than the average annual streamflow of Las Cuevas River (6.6 m3/s), butsimilar to the instantaneous streamflow of this river (157 m3/s, 2-year recurrence time).