Quantitative Skills > Teaching Resources > Activities > Estimating Exchange Rates of Water in Embayments using Simple Budget Equations.

Estimating Exchange Rates of Water in Embayments using Simple Budget Equations.

Alyn C. Duxbury, University of Washington and Keith Sverdrup, University of Wisconsin-Milwaukee
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This activity has benefited from input from a review and suggestion process as a part of an activity development workshop.

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process as a part of an activity development workshop. Workshop participants were asked to peruse activities submitted by others in their disciplinary group prior to the workshop. The groups then convened early in the workshop to discuss the materials and make suggestions for improvements. To learn more about this review process, see http://serc.carleton.edu/quantskills/review_processes.html#2004.

This page first made public: Oct 23, 2009


In this exercise students will estimate the volume rate of water inflow and outflow for an embayment using simple water and salt budget equations that capitalize on the concept of steady state and conservation principles. The average volume of water in the bay and the total concentration of salt in the bay water are assumed to remain constant. These budget equations can be solved for water inflow and outflow knowing the rate of addition of fresh water to the embayment and the salinities of the inflowing and outflowing waters. Students will then be asked to calculate inflow and outflow rates for Puget Sound, Washington and the Mediterranean Sea given actual values of fresh water input and salinities of inflowing and outflowing water, and compare their calculations to actual measured values.

Learning Goals

Context for Use

Description and Teaching Materials

The exercise can be downloaded from this file in a form that can be given to the students.

Activity Description/Assignment (Microsoft Word 169kB Jul17 04)

Teaching Notes and Tips


There are both quantitative and qualitative assessments that can be made with this exercise. Quantitatively there are specific numerical answers that the students should obtain if their manipulation of the equations and subsequent calculations are correct. In addition, there are thought questions at the end of the exercise that require students to think about the validity of the measurements in light of real data.

The following file contains the answers to this exercise.

Activity Answers (Microsoft Word 34kB Jul17 04)

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