Review Questions for Midterm 2

The format of the second exam will be similar to the first. There will be some broad questions and some focused ones.

• When rain falls on a landscape, what different pathways can it take to get into a stream? What timescales (flow rates) would be associated with those various pathways?
• Sketch a hillslope and draw the water table, and different pathways that water can take to get to the stream in the bottom of the valley.
• Imagine a rain storm drops an equal amount of water on two adjacent watersheds of equal size and shape. One watershed has lots of clay soils and little vegetation. The other has sandy soils and lots of vegetation. Draw a timeline of water discharge from a stream at the bottom of each of these watersheds.
• Imagine a rain storm dumps a lot of water on Northern California. Draw the discharge from Copeland Creek on campus, and from the Russian River where it meets the sea. Pay attention to the timing of the peak discharge as well as the relative magnitude of the peak.
• How does sediment move down hillslopes?
• How does cattle grazing affect streams and hillslopes in Sonoma County?
• What factors control sediment transport in rivers?
• How would clear-cut logging affect the sediment budget of a small mountain stream?
• How would installing a dam affect the sediment budget of a river?
• Know something about each of the factors that affect the sediment yield from a basin.
  1. climate (precip, vegetation)
  2. basin size
  3. elevation/relief
  4. rock type
  5. land use
• How can storage of sediment within a basin affect the yield from that basin (Tahoe example)?
• What distinguishes a laminar flow from a turbulent flow? Which type is most common in nature?
• The Reynolds number is Re = V * R / (μ / ρ) = driving forces / resistive forces . For each of the following scenarios, will the Reynolds number go up, down, stay the same, or "can't tell?" Why will it do that?
  1. The slope increases
  2. The stream gets wider and shallower
  3. The temperature decreases from 20 degrees C to 10
• What does Manning's equation tell us? V= 1.49/n*R^2/3*S^1/2
• What factors affect Manning's n? What does it mean for a river's ability to transport sediment when Manning's n is large?
• What is the difference between suspended load and bed load? Where would you expect suspended load to do most of the transport?
• How does the channel form affect the flow velocity within a stream? How does it affect sediment transport?
• What is secondary circulation and how does it aid in the formation of point bars?
• What is going on in this landscape? Why is the state border where it is? What has happened since the border was drawn?
• Choose a fluvial landform. Where would you expect to find it in relation to the basin, or the river? How does it form? Under what climate conditions would you expect to find the landform? Does the landform change during low river flows? Bankful flows? 100-year floods?
• Sketch 4 successive overbank deposits on the floodplain next to the channel. Label where you would expect to find coarse sediment and fine sediment.
  
• Why is the floodplain of the Nile River in Egypt such a good place for people to live?
• Describe two mechanisms by which terraces can form in a river valley.
• If you wanted to distinguish between an alluvial fan that was deposited by alluvial processes from one deposited by debris flows, what characteristics would you look for?
• From a geomorphologic perspective, why is New Orleans in such a bad place? Answer: Subsidence and compaction of the surface, sediment starvation, next to the coast and the natural wetlands along the coast are now gone, levees have changed the flood dynamics on the Mississippi.