Calculate the total mass of landslides that fall from the cone

Summative assignment: Part A – UEP Practical 2: Sandpiles

Part 1: Method: The experiment consists of two stages; Stage 1 is from zero, building the sandpile in this initial period of the experiment, the base-plate starts bare, and then the sandpile progressively forms as sand drops from the funnel (seen in figure 1) at a continuous rate from above. An Electric balance measures the mass of the base plate and sandpile every one second at very high precision to attain accurate data. During this period, the mass of the sandpile develops at an equal rate as sand drops onto the base-plate as no material is lost over the side. Consequently, during this stage of the experiment, the progress of the sandpile occurs at the mass flux rate. Stage 2 occurs when the side of the sandpile grows to reach the edge of the baseplate. At this point, the sandpile can grow no greater as the addition of sand steepens the pile to an angle greater than its angle of repose, and so the sandpile becomes unstable and now starts to generate landslides from the surface.  The three sands begin to behave differently, in terms of the mechanisms and types of landslides, magnitude (area, volume, mass) and frequency (average timing) between each landslide. The purpose of the set-up in figure 1 is to measure only the mass of the sand on the cone and not the sand which falls from it. Using this laboratory set-up, a record of the mass of the sandpile can be attained several times per second from the start to the end of the experiment. The experiments last for slightly different periods, but each includes a Stage 2 period long enough to measure a significant number of individual landslides.

 

Part 2: Summarising sandpile behaviour

1. To define a landslide by eye, a sharp drop in mass is shown, the drop must be more than approximately 0.70 kg over a period of approximately 1 s

Sandpile (Mixed) frequency of landslides (landslides per unit time) = 87 landslides

Sandpile (Pewter) = approx. 127 landslides

Sandpile (Yellow) = approx. 20 landslides

1. Calculate the input flux rate from the gradient of the relationship between mass and time during Stage 1 (cone building) of the experiment, for each of the 3 areas of sand:

 

 

1. Calculate the total mass of landslides that fall from the cone during the experiment. Consider the material input rate, and how much in total would be added over the period of the experiment. This input will be more than the final mass of the cone, with the difference being the total mass lost due to landslides. Enter your answer, and calculation, below:

 

 

1. Dividing the total mass lost due to landslides by the number of landslides in the experiment will allow you to calculate the mean landslide mass and volume for each sandpile. Enter your answers below:

 

1. Now calculate the erosion rate of the cone surface during Stage 2, by combining the time over which landslide occurred, the total mass loss, and the surface area of the cone. Erosion rate is expressed here as: kg m^-2 s^-1, and again enter your answers for the 3 sandpiles below:

 

Part 3: Comparing behaviour of the three areas of sand:

2. Figure 2. Is a graph that demonstrates the increasing mass in kg of the sand falling from the funnel onto the base through time in seconds. It shows stage 1 from 0 to approximately 125 seconds and then stages two onwards.
3. Name and describe the 3 mass movement processes in action on the sandpile?

 

1. Which sandpile generated the largest magnitude landslides, and why do you think this is? Mixed sandpile generated the largest magnitude landslides as shown

 

 

1. Which sandpile generated the most frequent landslides, and why do you think this is?

Pewter generated the most frequent landslides

 

 

1. your reading, suggests 3 Earth surface processes that might behave in a similar manner to this experiment?

 

 

 

 

Summative assignment: Part B – UEP Practical 3: Landslides

(Note: Please keep your assignment booklet to 2 pages when complete)

 

Part 1: Summarising landslide properties

 

1. Using the landslide data in a tabulated format, calculate the mean and median areas of your landslides. Express your answer in km² with an appropriate number of decimal places.

 

1. Using the landslide elevation data in a tabulated format (extracted from the DEM), calculate the mean and median elevations of your landslides. Express your answer in km with an appropriate number of decimal places^.

 

1. What are the maximum and minimum elevations at which landslides occur?

 

1. Why might the mean and median be different? Why is this useful?

 

 

 

 

Part 2: Mapping your landslides:

Compare the behavior of the 3 areas of sand in the experiments and answer the questions below when you have finished the experiments.

 

Using the instructions in the practical video, make a 2-part map of your detected landslides. Your map must have:

 

1. The mapped landslide vectors overlaid on the Image (this is part 1 of the map).
2. The mapped landslide vectors overlaid on the DEM (this is part 2 of the map).
3. A scale bar. Both parts 1 and 2 must be shown on the same scale.
4. A north arrow
5. A legend that indicates the color of the landslide vector and the range of altitudes in the DEM as a function of color.

 

 

Part 3: Write a concise description of the results of this practice.  To do this, write a flowing text of 250 words that describes and presents the numeric results and observations in part 1 in the text and the map of part 2 as a figure.  Do not use bullet points, your results section must be presented as unbroken sentences that would allow a reader to learn about the properties of the landslides mapped in the QGIS practical.

Summative assignment: Part A – UEP Practical 4: Comparing Sandpiles and Landslides

(Note: Please keep your assignment booklet to 2 pages when complete)

 

Part 1: Method Write a concise description of how you analyzed the data (maximum 200 words). Refer back to the guidance on a good method provided in Practical 2.

 

Part 2: Results: Summarising landslide behaviour

In this section, you need to use the graphs that you produced in this practice to describe the following behaviors. This is a results section, and so you should just describe the graphs, rather than trying to explain why they are like that. Include figures to support your descriptions.

 

1. Describe the magnitude-frequency behavior of the three sand types, and the similarities and differences between them.

 

1. Describe the magnitude-frequency behavior of the two sets of landslides, and the similarities and differences between them.

 

Part 3: Discussion: Comparing the behaviour of sandpiles and landslides

Write a one-page discussion that addresses the following points/questions. Remember that a discussion section should draw on your wider reading around the subject. You can include extra figures here if they are relevant and support your discussion.

 

Do the findings from practical 2 (sandpiles) and the start of this practical explain your sandpile magnitude-frequency plots? Explain how.

Does the difference between the two GIS methods explain the landslide magnitude-frequency plots? Which method do you think is more representative?

Discuss how both the sandpile and landslide magnitude-frequency plots compare to other magnitude-frequency plots that you have identified in your reading

Discuss whether your work in all three practicals suggests that sandpiles can be used as an analog for landslides.

 

 Figure 1. Side-view of the sand-pile experiment set-up. (Durham University, 2020/21)

 

 

Figure 2. Mass of each sandpile, yellow, mixed, and pewter against time in seconds from zero