Bathymetry Labbbbbbb2
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Wayne State University *
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3220
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Geography
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Feb 20, 2024
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7
Uploaded by ProfessorToad1038
Introductory Oceanography Lab EARTH 223/ENVIRON 233 Seafloor Bathymetry Part 1 - Topography/Bathymetry Maps 1.
What is the difference between topographic and bathymetric maps? (2 point) Topographic maps have contour lines that express elevation, while bathymetric maps have color scales that are used to express depth. Topographic maps include local infrastructure while bathymetric maps include info used for sailing. 2.
What do the concentric lines on a topographic map represent? (2 point) They represent a specific elevation/depth. 3.
What does it mean if topographical lines are close together? Far apart? (2 points) If the lines are closer together then the depth or elevation is very steep and vice versa. 4.
Locate the following points on the topographic map and describe the type of topography or landscape that you would find there. (3 points) A.cliff C. Gentle slope J. flat 5.
Which area has a steeper slope, O or M? (2 point) M For questions 4 and 5, you may confirm your answers with the 3D model of the topographic map.
Part 2 - Lead Line Activity In this activity you will learn how early hydrographic surveys were able to create bathymetric maps of the seafloor without being able to observe it directly. In addition you will learn how decision-making can affect the results that your research team will produce. Instructions: ●
Each group will be given a cardboard box with 176 holes. The bottom of the box has some sort of 3D topography that you will measure indirectly. First, you will need to choose how many measurements you want to take and where they should be located. ●
Once you have chosen the measurements that you will take, insert the metal stick into the hole and measure how far the stick can travel into the box before touching the bottom. Record this in the appropriate box. ●
Now that you have all of your measurements, you will create a bathymetric map. To do this you can connect the boxes of similar depth with topographic lines or color boxes of similar depth with similar colors. If you choose to color in the boxes, make sure you include a color-key (8 points for your map) 1.
Describe your topographic map. What kind of seafloor features can you identify based on the map that you have created? (4 points) Some points in our map have a higher elevation than others. The elevation fluctuates on our map. A
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Does this map have high resolution or low resolution? How much detail can be expressed using this method? How would you increase the resolution? (3 points) Our map has low resolution, just because we did not plot that many points.There is still a lot of detail even though there is not that many points plotted. I would increase the resolution by adding more points. 3.
How did your choice of where to take measurements affect your results? How does this relate to how real scientific surveys must balance quality of results vs. cost, resources, or time? (3 points) We decided to spread out our points. This relates to scientific surveys because just like in scientific surveys, we had to choose our points, but also work with the materials we had with us. We only had certain materials, and that is similar to how scientists only have certain instruments to do their experiments. Part 3 - Sonar and Travel Time 1.
Now, let’s think about acoustics in the ocean and how SONAR is used to map the seafloor. a.
What is a typical velocity of sound in seawater? (2 point) The typical velocity is 1507. b.
What is the depth of the deepest point of the Earth’s Oceans and where is it located? (2 point) The depth of the deepest point is in the Mariana Trench and is 10,929 meters below sea level. c.
Use your answer from part a and b to determine how long it would take a sound wave to travel from a ship at the surface to the deepest part of the ocean and back? (please show your work) (4 points) Depth/velocity=10929/1507=7.25 Sound travel time=7.25secs d.
How long would it take a sound wave to travel from a ship at the surface to a location with a depth equal to the average depth of the world’s oceans? (4 points) 3,688/507=2.46 2.46/2=1.23secs for sound wave to travel 2.
Now that you have calculated the amount of time that it will take a sound wave to travel from a ship to the bottom of the ocean and back, we will next explore how this data would be useful for studying seafloor bathymetry. a.
Imagine that a ship sailed across an ocean basin from the coast of one continent to the coast of another continent collecting acoustic data every 100km near the
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