Runoff Generation in Forested Watersheds- A Half-Day Shortcourse
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Presenter: Jeff McDonnell, Richardson Chair in Watershed Science, Oregon State University
Length: 9 parts, 3 hrs, 1 min and 16 s
View: Part 1 | Part 2 | Part 3 | Part 4 | Part 5 | Part 6 | Part 7 | Part 8 | Part 9
Topics:
Part 1
- Runoff Generation in Forested Watersheds
- Introductions
- Background
- Benchmark papers
- Good basic material
- Advanced material
- Journals you should consult...
- Basic question that will be addressed
- Traditional forest hydrology
- Problems with the paired watershed approach
- What this course will address
- Mechanisms -our focus
- Why these flow pathways and mechanisms are important
- Water residence time is important
- What we will and will not cover
Part 2
- Hillslope and watershed hydrology
- Experimentalist and Modeler
- Shortcourse outline
- Example locations
- Runoff Generation Overview
- This section
- Our History
- Runoff generation at a point depends on
- Storm characteristics and watershed runoff
- Natural conditions for infiltration excess overland flow
- Other factors that promote IEOF
- READ
Part 3
- Hydraulic conductivity of some materials
- Hydrological pathways
- Hewlitt and Hibbert's, 1967 VSAC
- SOF country
- Saturated areas: we can estimate based on topography
- Saturation overland flow
- Spatial and temporal dynamics
- Subsurface stormflow
Part 4
- How this might happen
- But, also can be highly preferential
- Dominant processes of hillslope response to rainfall
- Model conceptualization of these processes
- Proccess assumptions
- 3D Diagram
- Plot Scale
- This section
- Plot scale: e.g. Inceptisols
- What changes with depth
- Depth function
- Drainable porosity
Part 5
- Depth Function
- Drainable Porosity
- Ksat
- But don't forget....
- Soil profiles and cone penetrometer
- The plot scale simplified
- Pores
- Network-like
- If Darcy were alive today...
- How infiltration really works
- Infiltrations in macroporous soils
- Classification of macropores
- If we were to dig a pit
- In other words
- Macropores: engineers knew about this > 100 years ago
- Observations
Part 6
- Observations
- Plant Roots
- Hillslope Scale
- This section
- From vertical to lateral flow
- Vertical to lateral
- Surface and bedrock topography
- Hillsope trenching
- Surface and bedrock topography
- Flow distribution across the trench
- Transient saturation: Spatial pattern 5mm
- Transient saturation: 9mm
- Transient saturation: 16mm
- Transient saturation: 29mm
- Transient saturation: 50mm
- Transient saturation: 59mm
- Transient saturation: 61mm
- Threshold effects
- Threshold effects- a common observation
Part 7
- Fill and spill behavior
- Visualizing these processes
- Or, if a 2-layer system...
- Or, if a 2-layer system cont.
- Equals transmissivity feedback
- Back to our photo...
- Back to transmissivity feedback
- Pipeflow
- We see thresholds for lateral pipeflow also...
- Wherever we trench, pipeflow dominates
- Transient water table drives the pipeflow
- We've known about complexity for a long time
- Catchment Scale
- This section
- Soil moisture - Wet
- Soil moisture - dry
- Terrain relationships
Part 8
- Threshold Responses
- Back to the soil moisture diagram
- Threshold Responses cont...
- How catchment units sequence
- Why this is important
- Another way of looking at this
- It's not continuous
- Or, looking at this geochemically
- Discrete units that connect and disconnect
- From geographic source to time source
- The reality
- The old water paradox
- Not a new idea
- Stable Isotopes: hydrological tool
Part 9
- Two-component hydrograph separation
- Time source of water during events
- How old is the old water?
- A recent GEOREF search
- Residence time methods
- Convolusion integral
- Mean residence time
- Some reported mean residence times
- Watershed Model
- Summary
- Basic question that we addressed
- One proviso before ending
- REA: Something to keep in your mind
- REA: something that you can determine
- Hillslope and Watershed Hydrology
- Shortcourse Summary
- For a more extended virtual course...