Presentation on theme: "The False Promise of SPLATs (Strategically Placed Area Treatments ) By George Terhune."— Presentation transcript:
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. Finney Research Forester USDA Forest Service Rocky 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. ab cd
Disconnected vs Continuous
Effectiveness of a “Lattice” Pattern Depends on: Pattern: - thickness - spacing - overlap Treatment Fraction. Effectiveness of treatment. Wind speed. Wind direction.
Spread Rate Fraction Treatment Fraction
Disconnected vs Continuous Stronger Wind
Disconnected vs Continuous Calm 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 Treatment Fraction Continuous Discontinuous Worse Performance For equivalent treatment fraction and effectiveness, All continuous treatments perform better than discontinuous patterns. Spread Rate Fraction
SPLATs are not Finney SNFPA standard Slows the fire much less than 23% Finney example Slows the fire less than 77% Finney SPLATs Rt/Rm
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 Pattern Considered 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.