Water, Glaciation and Mass Wasting

This assignment is worth 10% of your total course mark. There are 100 points available overall. Complete all parts of this assignment by responding to each question in the space provided.
Please type your answers directly into this document and submit the assignment to your Open Learning Faculty Member for grading when you are finished. Do not remove the questions, or the number of points for each question, from the document.
Please remember to reference concepts that you get from outside sources. Concepts from the textbook and course units do not need to be referenced, but images, tables, or copied fragments of text longer than a few words from any source need to have in-text citations and references. Refer to the “TRU Citation Guides” for citing references in your assignments. If you’re not sure about what you need to reference, please see Student Academic Integrity and refer specifically to the plagiarism section (VI, 4).
Part A: Short-Answer Questions (20 points in total)
Answer the following questions as succinctly as you can. None of the answers should be more than a couple of sentences (100 words or less).

1. Identify the forces that drive the hydrological cycle. (1 point)
2. Building dykes to prevent river flooding is useful, but there are some drawbacks. Describe some of the negative consequences. (2 points)
3. Explain why clay, which is typically highly porous, is also normally quite impermeable. (2 points)
4. Explain how over-pumping in one well could lead to another nearby well going dry. (2 points)
5. What was the approximate difference in mean global temperature between a glacial period and an interglacial period during the Pleistocene, and what is the origin of the Pleistocene glacial fluctuations? (2 points)
6. The following diagram is a copy of Figure 16.2.7 from the textbook. Explain why the rate of ice motion (blue arrows) increases up to a certain point, and then remains the same from there to the surface of a glacier. (3 points)

Figure A4-1. Stress within a valley glacier. Data Source: Environment Canada. From Physical Geology by Steven Earle (2019) used under a CC-BY 4.0 international license.

7. What are the textural characteristics of lodgement till? (2 points)
8. Describe how weaknesses within a body of rock (fractures, bedding, foliation, etc.) can contribute to mass wasting. (2 points)
9. Explain how the motion of a slide (either translational or rotational) differs from that of a flow. (2 points)
10. From the perspective of not contributing to mass wasting, what should be the primary consideration when constructing a building near to the top of a potentially unstable slope? (2 points)

References
Earle, S. (2019). Physical geology (2nd ed.). BCcampus. https://opentextbc.ca/physicalgeology2ed/
 
Part B: Exercises (50 points in total)
B1: Interpreting a river hydrograph (10 points)
Figure A4-2 shows the variations in the daily discharge during 1957 for the Elaho River, north of Squamish, BC.

1. Discuss the origins of the variations in discharge over the year by focussing on the following:
   a. The long period of low discharge in January, February, and March
   b. The increasing flow rates in early spring
   c. The high flow rates in summer
   d. The pronounced high flow-rate peaks in late September and in November and December
2. The Elaho River is a popular destination for white-water kayaking. Based on the information in the graph, which month should you pick if you want to book your holidays so as to maximize the likelihood of high discharges and lots of white water?

Figure A4-2. Daily flows on the Elaho River during 1957. © Steven Earle. Used with permission. Data Source: Environment Canada.
 
B2: Groundwater flow paths and rates (20 points)
The following diagram (Figure A4-3) shows a cross-section of a sandy aquifer. The black line is the land surface. The dashed blue line is the water table, and the dashed red lines are lines of equal hydraulic potential, with pressure levels shown in red numbers. The hatched area at the bottom represents impermeable unfractured granite.

1. Following the example given in Figure 14.2.5 in the textbook, draw several flow lines depicting the likely overall nature of groundwater flow in this region. (You can draw in the Word document itself if you are familiar with its drawing tools. If not, you could print the diagram, draw the lines in pen or pencil, take a photograph, and insert that into your Word document.)

Figure A4-3. Groundwater flow example for Exercise B2. © Steven Earle. Used with permission.

2. The elevation of the water table at the top of the hill (point A) on the right-hand side of the diagram is 43 m, and the elevation of the stream at the valley bottom (point B) is 8 m. The horizontal distance from the hilltop to the stream is 125 m. The sandy sediment has a permeability of 10-5 m/s (0.00001 m/s) and a porosity of 25%. What is the likely average flow velocity between points A and B?

B3: Field trip to observe evidence of mass wasting or glaciation (20 points)
Take a field trip somewhere in your region to look for evidence of either mass wasting or glaciation and take a photograph. You may be thinking that no such features are accessible in your region, but that’s very unlikely. If you need some help deciding what to look for and where, contact your Open Learning Faculty Member. If you already have a good photo that illustrates either glacial or mass wasting features, you could use that, but please include the date when it was taken. Whatever photo you use, you must have been there when it was taken.
If mountains are nearby, you should be able to find some glacial erosion features, such as a U-shaped valley or a glacial lake. You might be able to find close-up evidence of glaciation, such as a streamlined glacial feature (roche moutonnée or drumlin) or glacial grooves (also known as glacial striae). Or you might be able to find some glacial deposits nearby, such as unsorted glacial till or thick deposits of glaciofluvial sediments.
In addition, you may find some kind of mass wasting feature nearby, such as evidence of a slump, debris flow or rock fall, or tilted gravestones or trees on a steep slope. Road cuts are good places to look for mass wasting, especially where it was necessary to cut steep banks into one or both sides of the road. Mass wasting also is common along lake or ocean shorelines or where stream water has eroded steep slopes.
Take a photograph, making sure to provide some context in the background. It might be a good idea to take a couple of photographs, so you can include more than one perspective or get a close-up of some important features.
In a few sentences, describe where you went (and when). Include the names of roads, mountains, rivers, lakes, beaches, etc., so your Open Learning Faculty Member can figure out where it is (or else provide a map), and—most important of all—write a description of what you saw and how you think it formed.

 
Part C: Longer Questions (30 points in total)
Please answer the following questions. Write as much as you think is necessary to address each question, but be as concise and clear as possible. Feel free to use point-form or a table rather than standard essay format. You do not need to reference the text or the material in the course units (except images or quotations), but if you use any outside sources, provide in-text citations. Use any referencing style that you are comfortable with.

1. Investigate the source of the water that flows out of your tap. Where does it come from, how is it treated, and how does it get to you? Briefly describe some potential risks to the quality and quantity of that water. Suggest some steps that you and your neighbours can take to ensure that your source of water does not become contaminated, and that the supply continues to be adequate for your community. (15 points)
2. British Columbia’s Sea-to-Sky Highway (Highway 99), between Horseshoe Bay and Pemberton, is prone to relatively frequent and dangerous mass wasting events. Based on the information in the textbook, the course units, and any other sources that you can access, describe the two most dangerous types of slope failures that have occurred within the past 50 years along this route and some of the steps that have been taken to mitigate the risks. (15 points)