Density flows susceptibility assessment in the Blanquito river basin, Tucumán province, using Drone and free software

Abstract

In January 1987 the Blanquito river basin was affected by a debris flow event that caused severe damages in the locality of Tafí del Valle. Several houses were hit by the debris flow and the bridge of 307 provincial route collapsed generating the temporal disablement of the route to the Calchaquíes valleys. In spite of this antecedent, no hazard mitigation measures were made in an area with a huge urban growth during the last 20 years. Therefore, the aim of this work is the assessment of density flows generation and propagation potential in the Blanquito river basin, combining geomorphometric information, field data, historical information, and hydrological models. Dominant processes that would be generated by exceptional rains in the basin would correspond to debris floods that can affect specific sectors of the village. The 1987´s event reconstruction showed that the process was a debris flow that affected an area of 614000 m² with a peak flow discharge of approximately 600 m³/s. The magnitude and type of flow that took place in the Blanquito river basin would respond to an event of extraordinary characteristics generated by the breach of a landslide dam during intense rainfalls. The possibility of a new event occurring again is high because rock avalanche deposits were identified that are currently partially obstructing the river.