CEE 577 |
28 March 2006 |
Closed book, 1 sheet of notes allowed.
Answer 2 of the following 3 questions. Please state any additional assumptions you
made, and show all work.
I.
(50%) Whole Hog
creek flows through and area of the North Carolina Piedmont that is heavily
populated with pig farms. The creek
discharges into a lake used for recreational purposes. Concern over phosphorus loading of the lake
has led to a short-term study of nitrogen imputs during storm events. Data from this brief, 8-day survey period is
shown below.
a.
Determine the
total phosphorus concentration for each day using the standard log-log model
b.
Estimate the mean
mass loading of phosphorus (in kg/d) into the reservoir based on these values.
Day |
Flow (m3/s) |
Total Phosphorus
Concentration (µg/L) |
1 |
0.2 |
|
2 |
0.5 |
12 |
3 |
4.2 |
|
4 |
13.1 |
55 |
5 |
2.2 |
|
6 |
8.3 |
|
7 |
2.3 |
|
8 |
0.9 |
|
II.
(50%)
Year |
Output (batteries/yr) |
2005 |
5,800,000 |
2010 |
5,100,000 |
2015 |
4,400,000 |
2020 |
3,700,000 |
2025 |
3,000,000 |
III. (50%) On a
separate sheet of paper, answer any five (5) of the following questions.
A.
Describe the difference between mechanistic and
empirical modeling
B.
Is a first order reaction always faster than a zero
order reaction? Explain.
C.
Sketch out a qualitative concentration vs distance
(downstream) profile for a river with a point discharge at x=0 and a
distributed source that runs from x=3 to x=6 miles. Show qualitatively how increases in the 1st
order decay rate for a pollutant changes this profile.
D.
Explain the relationship between Secchi-disk depth and
lake trophic state. Why is there such a
relationship?
E.
Describe 3 different methods for determining stream
velocity.
F.
Describe 2 different ways of measuring drainage basin
area
G.
Describe the factors that determine re-aeration in
rivers, and contrast this with the factors that determine re-aeration in
lakes. In your description, relate
micro-scale processes (molecules) to macro-scale (bulk water or air)