1. Cumulative Impact Estimation for Landscape Scale Forest Planning
Finn Krogstad & Peter Schiess
U. Washington, Forest Resources

2. Cumulative Impact topography soils management vegetation landsliding
sediment
management
down wood
elevation
peak flows
shade
rainfall
habitat

3. Overview Polygon vs. Grid Grid: new tool or paradigm shift
Spatial Calculus

4. Spatial Hydrology

5. Polygon Data glorified mylar
vegetation(x,y) y
topography(x,y) x
soils(x,y)

6. Non-Spatial Hydrology: rainfall-runoff black boxes
time
rainfall, runoff

7. Polygon Hydrology: summing black boxes

8. Polygon Blocks multitudinous approximation
0.6
1.2
1.8
2.4 3
0.6
1.2
1.8
2.4 3
Distance
from stream
Elevation
Aspect

9. Polygon vs. Grid reducing polygon size

10. Grid Hydrology: summing point processesET R I S

11. Gridding the Universe Grid makes the polygons small
More general that polygons or points
Topography (slope, aspect, etc.)
Raster data (precipitation, vegetation)
Grid stacks and grid algebra
Focus on point processes (F=ma)

12. New Tool or Paradigm Shift
Just a New Tool
New tools always come along
Won’t Grid be replaced in turn?
Paradigm Shift
General problem solving approach
Focus on physical processes not solution

13. Analogy: Calculus-based Physics
You can teach non-calculus physics
case specific and clever solutions
Learning calculus allows
general situations and direct solution

14. Grid Calculus existing hydrologic algorithms

15. FLOWACCUMULATION integrating contributing area

16. FLOWLENGTH integrating down flow path

17. Conclusion Grid for experts: Polygon for others
Teach physical process, not solutions
Other fields (ecology, forestry, etc.)