Lec 16: Runoff Generation III

Question 1

How do hillslope runoff pathways affect nutrient and sediment flushing?

Answer 1

nutrient flushing changes depending on:
- the time of the year
- tributaries in the same watershed

Question 2

Compare the 2 different forms of overland flow (HOF and SOF) in regards to:

• precipitation
• infiltration
• temporal characteristics
• spatial distribution between regions
• spatial distribution within watersheds

Answer 2

• precipitation
  HOF: intensity is critical
  SOF: duration is critical
• infiltration
  HOF: infiltration capacity is a critical factor
  SOF: infiltration capacity is not a critical factor
• temporal characteristics
  HOF: occurs quickly after onset of precipitation
  SOF: occurs only when soil is saturated
• spatial distribution between regions
  HOF: Semi-arid regions and/or impermeable soils with little vegetation
  SOF: Humid regions with well-developed soils and vegetation
• spatial distribution within watersheds
  HOF: Can be present anywhere in a given
  watershed
  SOF: Mainly present in riparian zones and valley bottoms

Question 3

Can different overland flow and subsurface flow mechanisms occur at the same time?

What affects the spatiotemporal variability of flow pathways?

Answer 3

yes, however there are shifts between active and dominant pathways in space and time

Antecedent wetness conditions and watershed characteristics play a central role in the variability of flow pathways