Debris flow susceptibility map of the chañaral province - Chile

Abstract

Debris flows are geomorphological events known in Chile as “aluviones”. They are water flows that carry large loads of debris and sediment, and can cause a flow with a volume 2 or 3 times greater than a normal flood. The Chañaral province has geomorphological, hydrological, and anthropic characteristics that favor the occurrence of debris flows in case of heavy rainfall. The anthropic factor is reflected as a potential risk factor due to the type of land use developed. Much of the communities urban area are settled either in El Salado riverbed or too close to fluvial terraces or even in alluvial fans. Chañaral province communities were affected by an event of this nature on March 24 and 25, 2015. These communities present a history of occurrences of debris flow events, which is the main reason to create this province a susceptibility map In 2015 human, economic and losses of other nature were extreme, leading to urgent identification of the most susceptible debris flow risk territories and in order to promote resilience and mitigation for those affected, in order to promote the mitigation and resilience of those affected. The objective of this study is to map areas susceptible to the occurrence of debris flows through the use of algebra maps in GIS. The susceptible areas were zoned by ranges and the most susceptible sectors were correlated with the sectors most affected by the 2015 debris flow event. The correlation demonstrated that the areas identified by mapping, using map algebra, overlap the areas affected by the debris flow event analyzed.