Caroline Mullis[ES1]
Lab Report #5
Question1. A. Create a layout of the contour map, overlaying points file, “points.shp” (complete with cartographic elements, including authorship!), print it out, and hand draw watershed delineations.
B. Draw aline from basecamp tomountain peak (outlook), selecting the shortest, but flattest route. Turn in this printed map to the TA at the beginning of lab next week.
Printed. [ES2]
Question2. Why is it necessary to fill sinks in the DEM to delineate watersheds?
The DEM is the digital elevation model, it is necessary to fill sinks in this digital elevation to delineate a watershed because if cells with higher elevation surround a cell, the water is trapped in that cell and cannot flow. Filling the sinks modifies the elevation value to eliminate these problems so we can move on with delineating.
Question3. How many directions are assigned when running the flow directionoperation? How do you think this might influence the resulting delineation?
When running the flow direction operation the number of directions that are assigned is eight. This would affect the resulting delineation because depending on the number of flow directions, the area will vary in size.[ES3]
Question 4. On your flow accumulation map, click on the in-stream point labeled "gauge".What is the value? How much area drains into that point? (6928)
Location Value: 355,008.592 4,370,886.256 Meters[ES4]
(using Identify)
Question5. What is the effect of changing the stream definition threshold? What does this suggest about the Horton stream order concept?
Changing the stream definition threshold is dependent upon area. This suggests that the Horton stream order concept of first order or unbranched being at the head of the watershed and so on is also dependent upon area, and can influence areas outside of a particular watershed.
Question6. Trace the flow path between base camp and the downstream, and basecamp and the ridge. Show the screenshot of the flowpath. Extra credit: How long is each flow path? What is the difference between the flow path and the crow's path for each? What defines the water flow path?
[ES5]
Question7. What is the area of your defined catchment? How does this area compare to the value of accumulation discussed in question 4?
Unable to complete with program. (emailed Emily/Craig)[ES6]
Question8. Create a layout of the resulting watershed delineation with the DEM, stream and point data (complete with cartographic elements).
Unable to complete with program. (emailed Emily/Craig)[ES7]
Question9. How does this delineation compare to the hand-drawn contour map? How does the flow path in question 5 differ from the route drawn in question1.
Computer made delineations for the most part are always more accurate than hand-drawn, because the ability of precision the computer has.[ES8]
[ES1]16/25
[ES2]Traced the wrong path. (-0.5)
[ES3]Water can flow in an infinite number of directions but eight directions is limiting. (-0.5)
[ES4]6928*100m^2=692,800m^2 is the area that drains to this point. (-0.5)
[ES5]Did not trace flowpath. (-1)
[ES6](-3)
[ES7](-3)
[ES8]Well, you didn’t get the final product, but that’s basically right. Nonetheless, since the final product was not made, you couldn’t compare the computer-generated output to the hand-drawn output. (-0.5)