Were merely storm-landslides driven by the 2015-2016 Niño in the Mendoza River valley?

MOREIRAS, STELLA M.; MOREIRAS, STELLA M.; ARANEO, DIEGO; ARANEO, DIEGO; PONT, IVAN VERGARA DAL; PONT, IVAN VERGARA DAL

LANDSLIDES

SPRINGER HEIDELBERG

Año: 2018 vol. 15 p. 997 - 1014

1612-510X

Since Holocene time, above-mean precipitations recorded during El Niño warm ENSO phase have been linked to the occurrence of severe debris flows in the Arid Central Andes. The 2015-2016 El Niño, for its unusual strength, began driving huge and dangerous landslides in the Central Andes (32º) in the recent South Hemisphere summer. The resulted damages negatively impacted on the regional economy. Despite of this, causes of these dangerous events were ambiguously reported. For this reason, a multidisciplinary study was carried out in Mendoza river valley. Firstly, a geomorphological analysis of affected basins was conducted estimating morphometric parameters of recorded events such as velocity, streamflow, and volume. Atmospheric conditions during such events were analyzed considering precipitations, snow cover, temperatures range and the elevation of the zero isotherm. Based on our findings, the role of the El Niño on the slope instability in the Central Andes is more complex in the climate change scenario. Even though some events were effectively triggered by intense summer rainstorm following expectations, the most dangerous events were caused by the progressive uplifting of the zero isotherm in smaller basins where headwaters are occupied by debris rock glaciers. Our research findings give light on the dynamic coupled system ENSO-climate change-landslides (ECCL) at least in this particular case study of Mendoza river valley. Landslide activity in this Andean region is driven by wetter conditions linked to ENSO warm phase, but also to progressive warming since XX century in the region. This fact emphasizes the future impact of the natural hazards in Andean mountain communities.