Estuaries and Conservation of Mass and Volume

Reading

• Reading that I have made (Here)
• See also Sec S8.8 of the Supplemental of Talley et al, available Here.

Things to Learn:

Estuaries

• In figure 3, what direction does each layer flow in order to reach “steady-state”?
• If the density differences between the layers are equal, which layer will initially have the strongest flow?
• what are the units of salinity?
• how do you think salinity is measured to make the figures in the reading (i.e. Fig 5,8, and 10)?
• What is an “isohaline” and “isopycnal”? Why are the terms interchangable in an estuary?
• What is meant by the term “steady state”?
• What are the types of estuaries and what parameters determine their classification?
• What factors govern the estuarine flow that can change in time?
  
• Be able to describe the effects of topographic blocking in fjords.

Mass (of, for instance, salt) and Volume Conservation

• Why is it OK to ignore the density of the water when we conserve the volume of water?
• If water flows through one hose twice as fast as through an identical hose, how does the volume transport between the two hoses compare?
• If water flows the same speed through two hoses, but one hose has twice the diameter of the other hose, how does the volume transport in the two hoses compare?
  
• If we were interested in the transport of salt down a hose, how might we quantify that? i.e. how would we measure how many grams of salt per second are travelling down the hose?
  

Knudsen Relation

• What is the salinity of a river?
• Based on the Knudsen Relation, which term represents the salt transport into the fjord in $ g/s $?
• Assuming the fjord is in steady state, write an equation for the volume budget $m^3/s$, and a second equation for the salt budget (all terms are $g/s$ ).
• Assume $ R $, $S_i$, and $S_o$ are all known, show that $Q_i = (S_o R)/(S_i-S_o)$
• If there is no mixing of the river water, what is $S_o$, and how big is $Q_i$?
• If there is lots of mixing, what happens to $S_i-S_o$ and thus $Q_i$?
• If you were to do the Knudsen calculation on a fjord-type estuary versus a flood-plain estuary, which do you think would tend to have the smallest difference between the salinities of the outflowing and the inflowing water?
  

Exercises

Please do the questions at the end of the reading based on the Juan de Fuca observations by Masson and Cummins (pages 15-17). Do not do the “Practice questions” on page 18 (here).

Last Modified: 09 July 2018 Licence: Creative Commons Attribution required, non-commercial uses (CC BY-NC 4.0)