The False Promise of

SPLATs

(Strategically Placed Area Treatments )

By George Terhune

The SPLAT Strategy

SPLATs are based on the “Finney Effect,” a theoretical concept from the paper

Design of Regular Landscape Fuel Treatment Patterns for Modifying Fire

Growth and Behavior

by Mark A. FinneyResearch Forester

USDA Forest ServiceRocky Mountain Research Station

The “Finney Effect”

A well defined pattern of area treatments can:

• Slow the fire in treated units, • Cause the fire to zig-zag around treatments,

and thus• Slow the overall forward spread rate, and• Moderate fire effects in both treated and

untreated areas.

“The maximum effect on the forward spread rate…

occurs when the treatment units cause the fire to spread

through them at the same rate as it spreads around them.”

( Finney, 1998 )

Finney’s Examples

a. No Treatment.

b. Continuous lines.

c. “Lattice” Finney.

d. “Herringbone” Finney.

In b, c, and d, 19% of the landscape is treated.

Treated area Rate of Spread is 1 / 10 of ROS in the untreated matrix.

a b

c d

Disconnected vs Continuous

Effectiveness of a “Lattice” Pattern

Depends on:• Pattern: - thickness - spacing - overlap• Treatment Fraction.• Effectiveness of treatment.• Wind speed.• Wind direction.

Spr

ead

Rat

e F

ract

ion

Treatment Fraction

Disconnected vs ContinuousStronger Wind

Disconnected vs ContinuousCalm Wind

Summary of Finney Pattern Deficiencies

• Finney geometry cannot be optimized.

-- Affected by wind speed & direction.

-- Affected by treatment type.

• Continuous lines always perform better.

-- Little or no wind effect.

-- Little or no treatment effect.

• Finney geometry is impractical to implement.

Performance of Treatment Patterns

0 0.3 1

Treatment Fraction

Continuous

Discontinuous

Wor

sePe

rform

ance

For equivalent treatment fraction and effectiveness,

All continuous treatments perform better than discontinuous patterns.

Spr

ead

Rat

e F

ract

ion

SPLATs are not Finney

0

0.2

0.4

0.6

0.8

1

0 0.3 1

SNFPA standard

Slows the fire much less than 23%

Finney example

Slows the fire less than 77%

Finney

SPLATs

0.5

0.1

Rt/R

m

0.77

0.23

Forest Service example of SPLATs

SPLAT Diagram from the SNFPA Final EIS. ( Vol 1, Ch 2, Pg 12 )

A fire burning around the treatments would not take the path shown in the FEIS. It would take the path shown on the right, which is 25% shorter.

Treatments that easily meet SNFPA Standards and Guidelines would readily burn through some of these treatments well before burning around them.

SPLAT Pattern from a Forest Service study on the El Dorado

There are numerous unobstructed fire paths with a south or southwest wind.

Finney PatternConsidered in the El Dorado study.

Impractical, AND there are still many fire paths virtually unobstructed.

Alternative Strategy

• Continuous strips of treatment.

Defensible Fuel Profile Zones

( DFPZs, Finney’s example “b”).

• Always performs better for equivalent amount and type of treatment.

• Not affected by wind speed.

• Less affected by wind direction.

A Direct Comparison:SPLATs vs DFPZs

Add the Same Fire to bothSPLATs and DFPZs

Potential uses for SPLATs

SPLATs vs DFPZswith roads considered