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Flow-type controls on tributary alluvial fan formation along the Andes (18-34°S)
Together with colleagues from Chile, Barcelona, and Indiana, we have just published a study exploring how the chronology of available Google Earth imagery can help classify debris flow deposits in the Andes.
https://www.sciencedirect.com/science/article/pii/S089598112500104X
What Did We Study?
What Did We Study?
Using both field observations and remote sensing, we classified recent debris flow events that have impacted 28 alluvial fans along a latitudinal gradient in the Andes.
Key Findings
Key Findings
Our results contribute to a better understanding of sediment dynamics in tributary-junction alluvial fans in Andean valleys:
Flow-type characteristics govern fan evolution, influencing their development across a broad latitudinal range.
The retention of sediments on fans largely depends on the original topography and the flow characteristics.
High-density flows contribute to fan aggradation, while cohesionless debris flows, hyperconcentrated deposits, and tractional flows enhance connectivity between tributary catchments and the trunk valley.
Implications for Land Use and Risk Management
Implications for Land Use and Risk Management
Alluvial fans are key areas for settlements and agriculture in Andean valleys due to their gentler slopes. However, in many arid regions, land-use planning has been poorly managed.
🚨 The fact that some fans have remained inactive for the past 20 years has created a false sense of security among communities, leading them to underestimate the risk of infrequent yet potentially hazardous debris flows.
Towards Safer and More Sustainable Communities
Towards Safer and More Sustainable Communities
Understanding sediment dynamics and the geomorphology of alluvial fans is crucial for mitigating the impact of natural hazards on developing communities in the Andes.
This research aligns with the Sendai Framework for Disaster Risk Reduction (United Nations, 2015), which emphasizes the importance of risk awareness and disaster preparedness.
🌍 By integrating our findings with this framework, we aim to foster safer, more resilient, and sustainable communities living on tributary alluvial fans in Andean valleys.
Debris flow facies-types defined in the field.
Examples of 'Activity' in tributary-junction fans
Fan-river coupling endmembers in the Iruya river watershed on optical satellite imagery from Google Earth. A. Fans partially coupled during the 2015 and 2016 debris flow event, contributing sediment to the main channel and forming a new fan lobe that led to main channel avulsion. B. Fans completely uncoupled during the 2016–2018 debris flow event, buffering all debris flow deposits on the fan surface.
a) Diagram modified from Harvey (2012) illustrating sediment supply and flood power relationships and b) diagram modified from Mather (2007), previously defined in Hutchinson (1988), showing flow types dependent on water amount and sediment supply based on unit weight values from Costa (1984, 1988), Hutchinson (1988) and Iverson (1997). c) The proposed graph after combinin diagrams a) and b), depicting reported flood events for visual comparison for 9 fans that were visited multiple times in the field during the last 20 years.
Examples of human occupation in tributary-junction fans.
Dear Colleagues,
I am pleased to introduce our upcoming session at EGU 2025, where we invite submissions on topics related to alluvial fan studies and river sedimentology. This session offers an excellent opportunity to share and discuss recent advancements in these fields
Please feel free to reach out if you have any questions. We look forward to your contributions and hope to see many of you in person at EGU 2025!
Inici de la pàgina web
Inici de la pàgina web
Comença una pàgina web dedicada a presentar resultats de les meves investigacions en el camp de les geociències.
[English]
I write this page in Catalan so that you can get to know this language. what I consider essential to give academic use to my page you will also find in English.
1 de Juliol de 2024
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