Sediment connectivity changes in an Andean catchment affected by volcanic eruption

Area of Science:

• Geomorphology
• Hydrology
• Environmental Science

Background:

• River systems are dynamic and susceptible to natural and anthropogenic disturbances.
• Volcanic eruptions drastically alter river morphology and sediment connectivity, posing risks to downstream settlements.
• Assessing sediment connectivity changes post-eruption is vital for effective watershed management.

Purpose of the Study:

• To investigate changes in sediment connectivity within a river catchment impacted by a volcanic eruption.
• To develop and apply a geomorphometric index for assessing sediment connectivity using open-source data.
• To analyze pre- and post-eruption sediment connectivity variations in the Blanco River basin.

Main Methods:

• Utilized open-source Global Digital Elevation Models and satellite imagery to derive topographic data.
• Developed a workflow to calculate the Index of Connectivity (IC) for assessing sediment flux impedance.
• Integrated field observations and satellite image classification to define land cover scenarios.

Main Results:

• Demonstrated a significant increase in sediment connectivity in the Blanco River basin following the Chaitén volcanic eruption.
• Identified distinct connectivity patterns related to the expansion of the active channel due to pyroclastic material.
• Validated the effectiveness of the IC in environments lacking high-resolution topographic data.

Conclusions:

• The study provides a robust methodology for assessing sediment connectivity in volcanically disturbed river systems, even with limited data.
• Findings enhance understanding of volcanic eruption impacts on riverine environments and inform watershed management strategies.
• The approach offers valuable insights for geomorphic research and disaster risk reduction in similar contexts.