Assignment 1
A mining company has applied for a permit to mine magnetite on the
Livingstone Ridge in southwestern Alberta. Magnetite is used in the refining
of coal, and the location near the Sparwood area of BC would make this site
very economical.
The company proposes to extract 10,000 m3/water per year from the small
stream illustrated on the accompanying map in order to wash the magnetite
ore that they will excavate. They argue that this water demand constitutes an
insignificant fraction of the creek’s annual discharge.
1.) Outline the watershed of the creek shown, in relation to the site that the
company proposes to extract water from (x) and calculate its area in km2. (4pts)
2.) Assuming a runoff coefficient of 100 mm per year (0.1 m) what would be the
expected annual average discharge at the proposed site? What percentage of
the average annual discharge are they proposing to draw?(3pts)
3.) If the creek is 2m wide and has a mean depth of 0.1 m (in an average yr)
before water is removed from it, what would be its average velocity (m/sec).
Assuming that the width and depth don’t change significantly what would be its
average velocity after water is removed from it at the proposed rate.(4pts)
x
4.) If we assume that the annual pattern of discharge of the creek follows the
same relative pattern as Gold Creek, near Frank in the Crowsnest Pass, and
we assume that the operation wishes to extract water at the same rate year
round, what fraction of the creek’s discharge would they be removing during
June, during October? (4pts)
5.) If we assume that the between year variability in discharge of the creek
reflects that of the region as a whole, and is similar to Gold Creek, what % of the
creek’s discharge would the operation be removing in:
a.) the driest year in 100
b.) the driest year in 20
c.) the driest year in 10
Use the probability paper provided to plot the probability distribution of the
creek’s discharge, and use this to make the above estimates. (10pts)
Discharge
m3/sec
o
Probability (percentiles)
6.) Suppose that the regional fisheries biologist estimates that 1 year in 20, the
creek is so dry that it either dries up, or has too little water to allow the resident
cutthroat trout to survive the winter. From the probability plots that you have
constructed, estimate the frequency of such die-offs, if the proposal is approved.
(7pts)
7.)In order to transport workers and machinery into the site the company
proposes to build a small road at the location shown.
a.) Roads are often badly designed in that they don’t allow for sufficient
drainage. Briefly outline some of the potential ecological problems that this road
could present to the stream habitat.
b.) At which sites should culverts be located, and how much discharge should
each one be able to handle given that the road is expected to last 40 years.
Explain.
c.) What are some of the factors that a fisheries biologist should consider if
consulted in regard to placement and installation of such culverts on first and
second order streams. (10 pts)
8.) Although some of the tools we use to make predictions are fairly crude, explain
why it is necessary to have such tools in dealing with proposed human activities on
the landscape and their hydrological and ecological consequences.(2pts)