geomorphology: a red hot tool for investigating catastrophic response to wildfire

Geomorphology: A Red Hot Tool for Investigating Catastrophic

Response to Wildfire

By

Mimi Diaz

Department of Geological Sciences

GELSS 2003 Arizona State University

Outline

• The chasm between science and society

• Rodeo-Chediski Wildfire statistics

• Geologic hazards associated with wildfires

• Geomorphology defined and applied

• Expected outcomes of this project

The Chasm

• Society– Everyday people

– Immediate problems

• Science, stereotype– “Different” people

– Abstract problems

• Science, reality– Everyday people

– Everyday applications

Why a Chasm?

• Communication!– Between scientists

• Different disciplines

• Different languages

– Between scientists and politicians• Politicians/broad focus/compromise

• Scientists/narrow focus/logic over reality

– Between scientists and general public• Theory vs application

• Different scientific backgrounds

• June—July 2002: the largest wildfire in modern Arizona history

• Destroyed nearly 470 homes and burned ~500,000 acres of forest

Photo courtesy Apache-Sitgreaves National Forest

Wildfire-Induced Geologic Hazards• Floods• Mud Flows• Debris Flows• Landslides

• Los Alamos, NM, 2000

• Banks, ID, 1997• Storm King Mtn, CO,

1994 Photo courtesy Jim Scheidt, BLM

Who is involved with wildfire?

• Society– Perpetrators

– Victims

– Firefighters

– Law enforcement

– Politicians

• Science– Wildlife ecologists

– Botanists

– Pedologists

– Hydrologists

– Geomorphologists?

What is geomorphology?

• The study of nature, origin, and development of landscapes through time, especially by:– Description

– Classification

– Prediction

• Time scales:– Recent geologic time (last 10,000 years)

– Human time (immediate past, present, future)

How do wildfires affect the landscape?

• Wildfire effect– Vegetation destruction

– Soil burning

– Rock fracturing

• Landscape response– Reduced soil cohesion

– Reduced water infiltration capacity

– Reduced strength

So, what does that mean?

Rodeo-Chediski Wildfire Area, August 2002

burned watershed + steep slopes + rain = mass movement

Rodeo-Chediski Wildfire Area, August 2002

What is Mass Movement?

• Occurs when material moves downhill uniformly (as in a landslide) or chaotically (as in a debris flow)

• Material includes dirt, rocks (small and large), trees, houses, vehicles, etc.

• Initiates uphill, terminates in lower portions of basins

How can mass wasting be predicted?

Observations + Applications = Forecast

Topography

Rock type

Burn severity (soil and vegetation)

Precipitation patterns

Drainage basin characteristics

Known physics and mechanics of mass movement

Type of mass movement expected

Location of movement

An area susceptible to debris flows:

Steep topography

High burn severity

Drainages present

The Job Doesn’t End There…

• Frequently, this is the point at which science stops

• Results may be written up in a professional journal or as a thesis

• But who tells the general public??

How to Cross the Chasm

Translation

+

Circulation

=

Proper Communication

Thank You!Mimi Diaz slidehazard@hotmail.com