Better quantifying crop vulnerability to tephra hazard : a standardized approach based on post eruptive impact assessements in Ecuador

Details

Supervisors

Delmelle, Pierre ; Ligot, Noa

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

Farming that takes advantage of fertile volcanic soils is vulnerable to the adverse effects of volcanic hazards. The Food and Agriculture Organization reports that agriculture absorbs 30% of damage and loss resulting from volcanic eruptions. One of the predominant causes of agricultural losses is the accumulation of tephra on crops. Given that tephra is the most widespread volcanic hazard, understanding its effects is crucial. This is particularly important considering that smaller explosive volcanic eruptions release finer tephra particles easily carried by wind, resulting in frequent, yet significant, threats to agriculture. Evaluating crop vulnerability to tephra fallout is a complex yet essential exercise for risk assessment. However, the hazardous, unpredictable, and often remote nature of volcanic eruptions poses challenges in obtaining data on crop vulnerability. Post-eruptive impact assessments (PEIA) have emerged as valuable sources of insight in this realm. Nevertheless, challenges persist in achieving homogeneous data collection to facilitate comprehensive analysis. To enhance the understanding of crop vulnerability to tephra fallout, this study introduces a framework – a database architecture – derived from five PEIA conducted across three volcanoes in Ecuador. This framework streamlines data collection, fostering comparability and facilitating data analysis across diverse case studies. By harnessing this database alongside PEIA data, the study assesses the impact of tephra fallout on exposed crops. It quantifies crop yield loss in relation to the principal hazard, tephra fallout, expressed in terms of mass loads. Interesting results from the analysis showcase a good ability of farmers’ to describe tephra fall characteristics. Further analysis of crop yield loss (CYL) for different tephra mass loadings confirmed a higher variability, that lead to understating that crop vulnerability is more importantly influenced by non volcanic factors at lower tephra loadings. The grouping of crops under categories highlighted certain similarities of CYL through the eruptive events studied. Suggestions for further PEIA were also described.