Post-fire Pulse

Diana Vieira

Whenever a wildfire impacts an ecosystem, one often reflects about what was lost, and few anticipate the imminent flooding and debris flow that can occur with the first rainfall event.

I have been waiting for that day
The day when rain falls over ash and charcoal
Like a stone
Falling on the ground without any obstacle.

The soil is dark, dry, and warm
Droplets are instantaneously transformed into vapor
Releasing a perfume
Where an invisible layer prevents soil and water to blend.

Out of my sight a situation evolves
Water starts flowing out of nowhere
Initially, small and shy
Rapidly evolving into a wrath of mud and debris.

Later becoming a uncontrollable giant
Bending trees, walls and bridges.
A dark turbulent flow
Tearing man-made structures and life apart. 

Until the moment when calm arrives
The flow gently goes quiet and unnoticeable
Slow and uneven
Leaving only black and emptiness behind.

The Science

This poem describes a post-fire rainfall-runoff event that often causes destructive debris flow. These events are incredibly energetic, and they are triggered by intense rainfall, although these events occur at lower rainfall thresholds compared to unburned conditions. If the burned area is large and the severity of the fire is high, these events can lead to serious flooding downstream, and the water transports more than just fine sediments.

The Poet

Diana Vieira is an Environmental Engineer researcher at the Joint Research Centre (European Commission). She investigates soil threats, in particular erosion hazard measurement and modelling, in recently burnt forest areas.

Next poem: Proximity by Susan Hughes