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

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

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

Spatial Hydrology

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

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

Polygon Hydrology: summing black boxes

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

Polygon vs. Grid reducing polygon size

Grid Hydrology: summing point processes ET R I S

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)

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

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

Grid Calculus existing hydrologic algorithms

FLOWACCUMULATION integrating contributing area

FLOWLENGTH integrating down flow path

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