EESB04

"PRINCIPLES OF HYDROLOGY"

Assignment #3b: Modelling Climate Change Impacts on Hydrology and Assessing Model Sensitivity (38 marks total; worth 10% of grade)

The objectives of the assignment are to:

1.  Apply  your   hydrological  modelling  skills  to  assess   possible  climate  change impacts.

2.  Understand the concept of sensitivity analysis.

3.  Develop precise observation and observation comparison skills with respect to hydrological data.

Instructions:

This is the 2nd step of your “two-step” assignment.

Do not use your own model from assignment 3a, but rather the complete and correct  model provided to you on Quercus, entitled “complete correct model.xlsx” . To avoid   providing the answers of assignment 3a to other students, this file will only be  released at 8 am on Monday, November 11. Note that on this worksheet, below the calculations, nearer rows 50+, are graphs encompassing the two-year period for 1)     precipitation, PET and AET; and 2) soil water storage and runoff. Professor Mitchell’s advice is not to touch these graphs. Follow instructions from your TA about how to complete this assignment and you will find that it is fairly straightforward.

Assignment format and submission instructions: Most of this assignment requires written answers, with the submission of just two graphs. Submit your assignment questions (as a Word document using 12-point font) via Quercus. You do not need to submit your Excel file this time. Where an answer requires a graph, copy the graph from your spreadsheet and paste into the Word document (suggest “paste special” and choose pdf or picture). Organize your assignment according to the order of the questions below. The assignment should be submitted as one Word document with embedded graphs and tables.

Note: Copying whole worksheets into new worksheets, to make small changes to parameter values, is key to success in this assignment. Your TA’s will discuss this in tutorial, but I provide the directions on the following page from the Internet (simplesheets.co) for additional reference.

How to Easily Copy Worksheets

Duplicate a Sheet by Right-clicking It

Assignment Questions

A) Climate Change Scenarios (21 marks)

1.        Change every average  monthly temperature  in the model to 2。C more than it currently is. Describe the main differences you observe for 1) PET and AET; and 2) soil water storage and runoff. State which of these outputs is most affected by the warmer temperatures. What is driving the change in this most affected output? (7 Marks)

2.       Go back to the original “complete correct model” (not your answer in the previous question).  Change  every  average  monthly  temperature  to  5。C  more  than  it currently is. Describe the main differences you observe in comparison to question #1 for 1) PET and AET; and 2) soil water storage and runoff. State which of the model outputs in the graphs is most affected by these even warmer temperatures. What is driving the change in this most affected output? (7 Marks)

3.        Using your output from question 2 above, change the total monthly precipitation to what  is  listed  here,  which  mostly  encompasses  earlier  and  more  spread-out precipitation (snowmelt) in the spring, as well as changes to summer precipitation. Describe the main differences you observe in comparison to question #2 for 1) PET and AET; and 2) soil water storage and runoff. State which of these outputs is most affected by the warmer temperatures and altered precipitation regime. What is driving the change in this most affected output? (7 Marks)

Yr1

Jan      Feb      Mar     Apr       May     Jun      Jul       Aug      Sep     Oct       Nov      Dec

0          105      98        58        66        81       75       25       69         156      101      51

Yr2

Jan      Feb      Mar     Apr       May     Jun      Jul       Aug      Sep     Oct       Nov      Dec

0          0           152      109      56       37       81         17        28         115      131      27

B) Model Parameter Sensitivity (17 marks)

4.        Rerun your  (complete correct) model using a mean daily temperature of 15。C every month and a mean sunlight hours of 12 hours per day for every month. Show the new graphs (1 - precipitation, PET and AET; and 2 - soil water storage and runoff).  What are the main differences you observe?  (5 marks)

5.       Go back to the original “complete correct model” (not your answer in the previous question). Explain what happens to your model outputs when you adjust field capacity in increments of 50 mm from 50 mm to 250 mm and note which output is most affected by these changes in field capacity.  No need to submit these new graphs, although you’ll have to make some to comment properly. To help in your interpretation, I suggest you keep your y-axis scale of your soils moisture/runoff graphs constant at 0-300 mm.  (6 marks)

6.       Again,  start with the  original “complete correct model” (not your answer in the previous question). Explain what happens to your model outputs when you adjust initial soil moisture in increments of 50 mm from 0 mm to 200 mm (while keeping field capacity constant at 165 mm). Also note which output is most affected by these changes in initial soil moisture. Again, no need to submit these new graphs, although you’ll have to make some to comment properly. (3 marks)

7.        Based on your answers to questions #5 and #6, is your model more sensitive to changes in field capacity or initial soil moisture? Expand your answer by describing specific observations in relation to the different graphed measurements. (3 marks)