GEOG 102 Week 8 Lab 3

John Smith

4 years ago

Objectives Outline a drainage basin.

Calculate a recurrence interval using actual stream data.

Apply these data to predict flood risk.

Grading Grading for the lab will be as follows: Remember the point score for the questions shows how many sentences or elements should be included in the answer. As always, answers will be graded on accuracy, completeness, spelling and grammar. As always, make sure your sentences are complete and your paragraphs are well organized.

? Part A Written component 35 pts ? Part B MyLab and Mastering component 10 pts ? Neatness, spelling and grammar 5 pts

Note on Academic Honesty: The written and online components for this week’s lab are to be done on your own. Working together with classmates is acceptable and encouraged, but the work you turn in must be your own words. Refer to the course syllabus and the OSU General Catalog for the university policies concerning academic dishonesty.

At the end of your lab, you must type or write the following words This work, including the on- line component is entirely my own. I did not copy the whole or any part of my answers to this this lab from anyone else, from a web site, from a book, or from any other source. Underneath these words, type or sign your name and date.

Part A

Draw and Calculate the following: 1. Your first exercise is to outline, with a colored pen or pencil, the drainage basin for the Big

Thompson River (Figure 3, page 6). Note that in a few places (red marker), some of this has been done for you (2 pts). Next, mark the following: (8 pts)

a. headwaters b. interfluve c. mouth, or location where the river flows onto the Great Plains

2. The next step is to calculate the flood recurrence intervals and rank flood events by their

maximum discharge and their recurrence intervals. From this data, it is possible to calculate the probability of the flood recurring. Table 1 (page 7) lists nine years of maximum daily streamflow stage (cfs) for the Big Thompson River. (6 pts)

GEOG 102 Week 8 Lab 4

a. In the third column, rank this data by year from the largest amount (rank of 1) to the smallest (rank of 9).

b. In the fourth column, calculate the probability, in percent, of the flood recurring using the formula: rank/( n + 1 ) × 100 ; where n = the number of years with available data

c. In column five, rank the recurrence intervals. This is determined by the following equation: RI = (N + 1)/M Where: RI = the recurrence interval N is the number of years the floods are on record M is the rank of the flooding event (largest flood M = 1) Because there are nine years of data, this calculation becomes 9 + 1, divided by the rank number you assigned

Analyze and Conclude 3. In your completed data table, how is the recurrence interval related to the rank and

probability of each years maximum discharge? (3 pts)

4. Based on your answer to question 3, what maximum discharge might residents along the Big Thompson River typically expect? Explain. (3 pts)

5. Does knowing the recurrence interval enable you to predict floods on the Big Thompson River during the next nine-year period? Explain why or why not. (3 pts)

6. In many areas of the world, accurate stream recurrence interval data now extend over one century. After a record (rank 1 flood) in these areas, the media often refer to it as a once in a century flood, or a 100-year flood. In your job as a watershed manager, does this mean that prospective home and business owners are safe from another event of that magnitude for more than the average human lifetime? Explain. (3 pts)

7. Looking at Figure 3 on the page 6, describe the difference in flow characteristics discussed in Section 10.5 (in your text) for stream water flowing in the middle of the canyon and the same water as it flows out of the mountains and across the Great Plains just below the Rocky Mountains. (3 pts)

GEOG 102 Week 8 Lab 5

8. Hypothesize how and why the following landscape changes might influence future floods in the lower sections of the Big Thompson River watershed: (3 pts) a. More urbanization b. A large forest fire c. A series of upstream dams

Part B Part B of this lab is online and continues to the impact of rivers on the landscape. Log in to Canvas to complete the online portion of this lab in the MyLab Mastering section.

GEOG 102 Week 7 Lab 6

Figure 3 Digital relief map of the Big Thompson watershed (NOAA)

GEOG 102 Week 7 Lab 7

Table 1 Data for calculating flood recurrence interval