Assignment EDMA4-1:
Introduction:
Before beginning this assignment, take a few minutes to read through a case study (link below) that demonstrates the use of digital mapping technology similar to the form you will be using today.
- As you read, be aware that there are some differences between this case study and what you will be doing today:
First, you will be producing a similar “case study,” but yours will most likely be much briefer (in other words, don’t be overwhelmed).
Second, this case study will mention specific data sources (i.e. aerial maps and Landsat MSS satellite images) that will not be emphasized in this assignment. GIS data come from multiple sources. This is good to realize and acknowledge, but for now you can bracket that information.
Third, given time constraints and where you are in terms of working on an actual watershed project, the “case study” you will produce will likely be hypothetical (or partially hypothetical). In light of this, you are encouraged take some liberties to fill out your scenario. This case study will help you recognize important pieces of the puzzle. For example, you might not know specific projected or historic land uses in your own scenario, but in this case study you can see how that information was important. This is the type of information that you might need to be creative with in your scenario.
- Here is what you should pay attention to as you read this case study:
First, notice how the presentation is organized (i.e. Study Area, Data Used for L-THIA Analysis, Land Use Change Scenarios, Analysis, Results and Discussion, Minimizing the Impact). Your assignment will be to produce a document in a similar form (more information on this can be found in section 3 of this assignment).
Second, pay attention to the use of L-THIA Analysis. This acronym stands for “Long-Term Hydrologic Impact Analysis,” which is a big name for an effective and user friendly program (you will be using this in section 2 of the assignment). As you read, don’t get bogged down by the details of L-THIA, but instead develop an overall impression of what this program does and how it was useful for analysis, results, and discussion in the case study.
Third, pay attention to how digital mapping was useful in analyzing, discussing, and coming to conclusions about this watershed and the various land use scenarios. For example, how did different land uses in different areas affect total runoff? What are the implications for decision-making? Do all high-residential developments have the same impact?
This case study will give you a good idea of the product you’ll be working on in this assignment. The following 3 sections will lead you through this process.
To read through the case study, visit the following website:
http://www.ecn.purdue.edu/runoff/documentation/case_studies/cuppy_mcclure.htm
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We will be using the Midwest Spatial Decision Support System Partnership (MSDSSP) website (http://www.epa.gov/waterspace/toolpage.html), which is just one of many tools available for digital mapping and GIS. This activity will lead you through three steps of using digital mapping for watershed planning and management:
1. Compiling data
2. Considering changes
3. Communicating information
Now that you've seen one example of how digital mapping is useful for watershed planning, you have one more task before beginning: choose a watershed or land area (of any size) that interests you . You will use this watershed throughout the assignment to learn how to compile data, consider the impact of changes to the watershed, and you will write a brief report on what you learn.
1. Compile
1. Go to http://www.epa.gov/waterspace/toolpage.html
2. Select Digital Watershed Mapping and click on the link http://www.iwr.msu.edu/dw
a. If you are interested in learning more about digital mapping, you could select "Site Info" to learn more about the Digital Watershed project. It provides a brief introduction to digital mapping.
3. Find your watershed in one of three ways:
a. Address Entry: Enter an address (street, city and state, etc.)
b. Map Entry: click on your national region. Get more specific from there.
c. Search Entry: Search by state, watershed name, or 8-digit HUC
**The server may be busy. If so, try reloading the page.
4. You should see a map of the 8-digit HUC watershed you have selected.
5. If you'd like to explore a little bit, choose some of the GIS Tools at the top of the map:
a. Clicking on the magnifying glass icon allows you to zoom in and out
b. The lightning bolt takes you to the EPA's "Surf Your Watershed" site
i. Learn more about groups active in your watershed, including contact information and descriptions
ii. Access EPA's "EnviroFacts Warehouse" for information on your watershed
c. "A" calculates land cover statistics
d. "V" gives a 3D visualization of the topography
e. "M" calculates soil erosion and deposition (You may want to zoom in before using this feature)
6. You can also see different "layers" of information on this map by using the bar to the right of the map. Simply select the layer(s) you wish to see and then click "update map.” This is a hallmark feature of digital mapping – the ability to “layer” information. Even so, at this time it is adequate to explore this feature very briefly.
7. Now choose the more specific watershed (this is currently and 8-digit HUC) you wish to focus on for the rest of this assignment . In order to do this, zoom in on the area of interest. You can adjust the “zoom factor” at the upper left corner of the page (the default setting is 2). A higher zoom factor will bring you closer with one click than a lower zoom factor. Zoom in until you see sufficient detail.
8. Use the green icon (between the blue arrow and the "i") to get more information on a smaller area. To do this, select that button and then click on the map.
9. You should see a screen that says "Queried Results for Spatial Data"
10. This page displays calculations of the selected watershed's total area, land use, and soil types.
11. This is good information to compile, but first check to make sure you have selected the area you wish to evaluate
a. click on the link below this data that says: “click here to change land use in your watershed and to see the Mapserver GIS display”
12. This will bring a new map of this smaller watershed.
13. Does the watershed boundary correlate to what you had in mind?
a. If so, you're good to go.
b. If not, find the button at the top of the map that says "Click Outlet and Run WD."
c. Select this button and then click the outlet stream of your selected watershed at the place where you wish for the map to stop.
14. Once you are sure you have selected the appropriate boundaries to your watershed, you can view information one of two ways:
a. You can stay on the map and view the same information graphically. This allows you to see where specific land use, etc. occurs. Try this by selecting "Land use" in the upper right hand box. Then select the "legend" link below. These maps update automatically.
i. Find the map of each layer for your watershed (Land Use, Hydro. Soil Map, and Curve Number Map). For each map, click on “Printable Map” and save each as a picture (right click, save as picture). Also save a copy of each map’s legend.
ii. Also select “Index Map” and a map of the state will appear with a red cross indicating where your small map is located. Save the map index as an image. (If you don't see a map right away, you might have to look for it on the tool bar at the bottom of your screen.)
b. Or, you can see this information in a data table. Go back to the "Queried Results for Spatial Data" page by selecting the "Run Hydrological Models" button. You can see the information about this watershed area, land use, and soil types.
Copy this table and paste it into a Word Document.
15. While on the “Queried Results for Spatial Data” page, you have the opportunity to calculate the percent of impervious surface. To do this select the “Calculate % Impervious” link. Add this information (copy and paste) to the Word document you just started.
2. Consider
In this section you will be using the L-THIA (long term hydrologic impact analysis) feature found on the “Queried Results for Spatial Data” page (the page with the table you just copied). The L-THIA link is located directly below the “Calculate % Impervious” button. For more information you should briefly view MSDSSP’s L-THIA PowerPoint Presentation(be sure to open this in another page or tab – right click and select “open link in new tab” or “new window”). After going through this presentation, come back to the “Queried Results for Spatial Data” page
1. Select the L-THIA link. This will take you to a page where the current scenario is represented based on land use and soil group.
a. Area is measured in acres by default, but you can change this to other units of measure (square miles, square kilometers, or hectares).
b. The statistics you see on this page should correspond to the maps you saved in the last section. Take a few moments to see how the soil groups and land uses shown spatially on the maps correspond to the data in this L-THIA table.
2. The L-THIA table allows you to consider changes to this watershed. Column 1 is the current situation. In Columns 2 and 3 you can enter in proposed changes. These changes can be hypothetical or they might reflect actual changes (either historic or proposed) in your watershed. Further, they could be beneficial or detrimental alterations.
3. Try it out for yourself by mixing the area, land use, and hydro. soil designations. You could even add new land uses in the open rows at the bottom of the table. Consider the maps you saved and this table to come up with 2 new scenarios. (For example, maybe there are currently 500 acres of forest on soil type B, but a 100 acre high-density residential development has been proposed. One option would be to take those 100 acres from the forested land. Now you would have 400 acres of forest on soil type B and 100 acres of high-density residential on soil type B).
***BE SURE THE TOTAL AREA ADDS UP THE SAME IN EACH SCENARIO, otherwise you may get an error message.
4. You will get a table for each scenario that includes hydro. soil group, land use, area, and average annual runoff volume.
5. At the bottom of this page you will find a table that relates soil type to land use and curve number (a prediction of runoff or infiltration due to a rain event) for the current scenario.
6. Copy and paste these tables to your Word document.
7. On the left side of the page you will see a number of links. Find the “Output” link. Under it you will see a small table with two additional links: “runoff” and “NPS.” These will allow you to produce a number of tables and charts containing more detailed information about each scenario.
a. Take some time to become familiar with the information and display options provided here.
b. Choose at least two tables/charts/graphs that help show the differences between the scenarios in your watershed. You will most likely have to save these as entire web pages (you don't have the option to save or copy the image). If you are unable to do this, simply make note of what you find. These tables/charts/graphs will be helpful to your communication efforts. (Recall the case study you looked through at the beginning of this assignment.)
3. Communicate
1. Just below the “Output” link you just finished exploring, you will find another link (the last on the L-THIA Results Output page) named “What Can I Do?” Select this link.
2. On the next page a table will be displayed. The right column of this table has the heading “Analyzing Results.” Select and read through the two links in this column:
a. Interpreting model results : This link will take you to a brief overview of L-THIA and the reasoning that makes it work. This overview can be helpful as you write analyze and discuss the results from your different scenarios.
b. Case studies: This link will take you to some case studies that used digital mapping and L-THIA in order to inform decisions. You already read the first one of these ( Comparative impact analysis of two land use change scenarios in the Cuppy McClure Watershed, West Lafayette, Indiana) before beginning this assignment. You might find it helpful to briefly read through the other two in order to get a better idea of what your communication effort might include.
3. After reading through these links, you should have a good idea of how L-THIA results are analyzed and utilized in real-world examples.
4. The final step of this assignment is to compose a report, presentation, or letter that incorporates the information you’ve compiled and the changes you’ve considered. If you find it helpful, you can use the case studies as examples to follow – BUT, don’t get overwhelmed! Try to be thorough and incorporate the information that these maps and data can uniquely address, but this can be a brief communication. Whether you choose to write a report or a letter (i.e. to stakeholders) or compose a presentation (i.e. for the general public), try to follow this outline:
i. Introduction to the area (i.e. what watershed, what characteristics?)
ii. Data cataloged (What data did you gather?)
iii. Scenario(s) considered (What changes are you considering? Where? or What changes have occurred throughout past land developments?)
iv. Analysis (In what ways, i.e. total runoff, types of runoff, do the scenarios differ?)
v. Results and discussion (What is the proposed best course of action after analyzing the different scenarios?)
TURN IN THE FOLLOWING:
2 Word Documents.
- The first document should have:
- Pictures of the maps (with legends) that you acquired in the “Compile” section.
- The table of results from the “Queried Results for Spatial Data” page, along with the %Impervious data.
- The table of scenario data from your L-THIA Results, along with other any charts and graphs that you may have saved from the “Consider” section.
- The second document should be your communication (i.e. report, presentation, letter)