SCHEDULE

1
SCHEDULE
2
ROAD-SIDE DITCH REVISITED
Revisiting the road-side ditch problem By how
much is the contributing area of each stream cell
increased in shifting from natural downhill
routing to roadside ditch interception? Does the
resulting change look different if you use
relative vs. absolute change?
3
ROAD-SIDE DITCH REVISITED
Revisiting the road-side ditch question Water
flows faster in ditches than through the soil. If
you count the ditch segments that feed directly
into streams as part of the stream network, then
map the flow length to streams with and without
road ditches. By how much is the average
flowlength above a stream cell reduced by adding
the roads?
4
RAIN-ON-SNOW REVISITED
Runoff from stands in the rain on snow zone is
more sensitive to harvest. Streams that have much
of their contributing area in the rain on snow
zone must be similarly sensitive. If the
rain-on-snow zone is 900-1200m, map the fraction
of the contributing area of each stream reach
that is in the rain on snow zone.
5
RAIN-ON-SNOW REVISITED
We might want to put special restrictions on the
rain on snow slopes above the most sensitive
reaches. Identify the stream cells whose
contributing area is mostly in the rain-on-snow
zone Identify the rain-on-snow cells that
contribute to these most sensitive stream
reaches.
6
OUTLINE

• Transportation Cost
• Streams
• Haul Routing
• Example

7
Transportation Cost

• Consider some rough cost values
• Skidding
• 30-60/mbf _at_500ayd
• Cable yarding
• 60-140/mbf _at_1000ayd
• Truck Haul
• 1/mbf/mile
• Combine using nested .con functions

8
STREAMS

• Prohibited areas such as streams
• can be modeled by very high costs
• or excluded with NULL DATA
• How do you handle road-stream crossings?

9
HAUL ROUTING

• Water flows down topographic gradient
• Traffic flows down cost gradient
• Hydrologic functions can then be used to identify
  traffic patterns.

10
Example

• In this project, the source cells are the last
  segments of the roads leading to the mill
  Roads223 Roads256
• What is the skidding cost in /mbf/ft if the
  average skidding cost is 30/mbf for a setting
  with an average skidding distance of 500
• Map skidding costs using this single cost
  everywhere across the landscape (no roads).
• Add roads with an appropriate truck haul cost,
  and rerun.
• Recalculate skidding costs assuming skidding
  costs increase linearally from 30/mbf for flat
  topography to 60/mbf for 40 slopes. Rerun haul.

11
Example (continued)

• Revise cost grid to prohibit skidding (but not
  truck haul) across streams.
• Soil erosion increases with soil disturbance. For
  each cell, calculate its traffic volume (number
  of cells that are accessed by skidding/driving
  over that cell). Which non-road cells get the
  most traffic? Should we add a road there?
• We might want to eliminate some of our road
  density. Identify and eliminate the road segments
  that carry the least traffic. By how much does
  this increase transport costs, averaged over the
  planning area?