Locating a Fire Tower Using GIS

Click Apply.  These are the major roads and will be the only ones you will consider in locating your fire towers.

21)  What is the most common land cover class away from streams?

22)  Why do you think the land cover class changes near streams?

Examine the land cover theme's table    again.  Use Field-->Summarize on the field that you indicated above (the land cover class field) to answer the following:

          61 Orchards/Vineyards/Other

Herbaceous Upland Natural/Semi-natural Vegetation

          71 Grasslands/Herbaceous

Herbaceous Planted/Cultivated

          81 Pasture/Hay
          82 Row Crops
          83 Small Grains
          84 Fallow
          85 Urban/Recreational Grasses

Wetlands

          91  Woody Wetlands

          92 - Emergent Herbaceous Wetlands

24)  What are the three most common land cover types in this region of South Dakota, according to what you see on your map?  List the names of the land cover types this time rather than the class numbers (such as "woody wetlands", rather than 91).

25)  Does the answer you gave to the three most common land cover types surprise you, given what you know about this area of the United States?

26)  Does your land cover table indicate the number of polygons where the land cover occurs or the amount of area covered by that land cover class?

Therefore, to assess how much area is covered by each land cover category for planning your fire towers, you need to first create a field that can hold the data, and then run statistics on that field.

Start editing the table and create a new field named "area".  Use the field calculate button to calculate this field to the following formula, preserving the square brackets in the formula:    [shape].returnarea

Stop editing and save your edits.  

Examine the data in your new area field.  

27)  What data does the new field contain?

Access the menu Field-->Summarize to create a summary table on the field landcoverclass.  In the dialog box that appears, use area for the field and summarize by sum, as shown below:

Press "add" so it appears the right side of the box.  Give the resulting table an appropriate name, and select "OK."  

28)  In your new table, sort the field sum_area.  Explain in your own words what this table is telling you.

29)  What are the 3 types of land cover that are most predominant in your area of study?

30)  Does this correspond with your answer to question 24 above, from your examination of the map?

Planning Fire Towers

Now that you are familiar with your data, you can address the problem of locating the three fire towers.  Recall your criteria where the fire towers need to be located:

30)  Because the first and second criteria specify that the tower needs to be in proximity to roads and rivers, what type of GIS function will you need to perform on them?

Using the query tool , select the roads that meet the criteria of "major"--that is, roads with a CFCC of A41.

31)  What percentage of the roads in the dataset are selected?  Show your work.

Now that you've selected the roads under consideration, use the Theme menu to create a buffer around only these major roads.  Make sure you use only the selected roads in your buffers (the major roads) and use the criteria above to determine the buffer distance.  Dissolve barriers between buffers.  Save your results as a new theme named roadsbuffer in your firetower folder. 

32)  Make an observation of the buffers around roads in your own words.

33)  Zoom in on one of the buffers and measure across it.  Is the buffer 200 meters from the road to the edge of the buffer, or 200 meters across the entire buffer?

Next, using the query tool, select the rivers that meet the criteria of "major", that you identified above.

34)  What percentage of the total hydrography features are selected?  Show your work.

Now that you've selected the rivers under consideration, use the Theme menu to  create a buffer around only these major rivers.  Make sure you use only the selected rivers (the major rivers) in your buffers and use the criteria above to determine the buffer distance.  Dissolve barriers, and save your results in a new theme named riversbuffer in your firetower folder.

35)  Is your buffered rivers theme a point, line, or polygon theme?

You have just addressed the rivers and roads criteria for your fire towers, criteria (1) and (2). 

Next, turn your attention to criteria (3), your elevation data.  Recall that the elevation criteria was to locate your fire towers on high hills of over 840 meters.  The elevation data you are working with was reclassified from the original raw elevations.  Categories of elevation of 6 and above correspond to an elevation of 840 meters and higher.

36)  Knowing this information, state what your elevation query statement needs to be:

37)  After querying the appropriate elevations, indicate how many elevation polygons are under consideration:

38)  Examine your map and note the terrain highlighted in yellow .  In what parts of the study area are the suitable elevations?

Save your selected elevations to its own shapefile by accessing this menu:  Theme-->Convert to shapefile.  Name your new theme elevhigh and store it in the firetower folder.

39)  Compare the number of polygons in your new table to the number selected that you indicated in question 37.  Explain the reason for the two numbers.

You have now worked with the first three criteria, for rivers, roads, and elevation.  Next, turn your attention to criteria (4), slope of the land.  Recall that the slope criteria was to locate your fire towers on flat slopes of 5% or less.  The slope data you are working with was reclassified from the original raw slopes.  Categories of slopes of 1 and 2 correspond to a slope of 5% or less.

40)  Knowing this information, state what your slope query statement needs to be:

41)  After selecting the appropriate slopes, indicate how many slope polygons are under consideration:

Save your selected slopes to its own shapefile by accessing this menu:  Theme-->Convert to shapefile.  Name your new theme "flat" and store the flat file it in the firetower folder.

42)  Examine your "flat" map.  In what parts of the study area are the suitable slopes (flat ground)?

You have now worked with four of your criteria:  rivers, roads, elevation, and slope.  Now, you need to find out where ALL 4 of the criteria are met.  To do this, you'll need to do run three intersections.   You can only intersect 2 data sets at a time.  Therefore, you will need to intersect as follows.  Use the following theme names:

Rivers buffer intersected with roads buffer: riv_rd  [A]

Result of [A] intersected with suitable elevation (elevhigh):  riv_rd_high [B]

Result of [B] intersected with suitable (flat) slopes:   riv_rd_high_flat  [C]

Recall from a previous lesson that to run intersect, you need to first go to File--> Extensions and engage the Geoprocessing extension.  

Now, you have a new choice on the bottom of your View menu called Geoprocessing Wizard.

Engage the GeoProcessing Wizard and run your three intersections.  You will use the geoprocessing wizard on the first two intersections, and a select by theme for the third, to avoid computer processing delays. 

First, intersect rivers and roads using the Geoprocessing Wizard and save the result as the theme  riv_rd.

43)  Make two observations about the pattern, shape, and the number of records in your rivers and roads intersection map (riv_rd).

Now, using the Geoprocessing Wizard, intersect your rivers and roads intersection result (riv_rd) with suitable elevation (elevhigh) to create riv_rd_high.

44)  Make two observations about the pattern, shape, and the number of records in your resulting map (riv_rd_high).

Finally, intersect this result riv_rd_high with flat to create riv_rd_high_flat as follows:

First, clear any selections in the flat file: 

Second, make riv_rd_high the active theme (raised up).  

Third, use Theme--> Select By Theme to "select features of active themes" that INTERSECT the selected features of the flat file:

This will select all of the flat areas that are also near roads, near rivers, and on high ground.

Access the table of your file riv_rd_high. 

45)  How many areas are selected?

Save these selected areas to their own theme by using Theme--> Convert to shapefile.  Name the shapefile riv_rd_high_flat and save it in your firetower folder.   Go to Theme--> Properties and rename riv_rd_high_flat to finalfiretowers.

46)  Make at least two observations about the pattern, shape, and the number of records in your final fire towers map.

Make the rivers theme active and then use the label button to label several rivers.

Looking at the pattern of the distribution of your final sites, they seem to be clustered in several groups in the southwestern part of the study area, and several groups in the northeast part of the study area.  

47)  Describe the location of these clusters in relation to St Francis, Rosebud, and the rivers. 

Your final criteria (5) is to note that the primary wildfire concern is with grasslands.  Change the legend for grasslands to map as single symbol.  Make the outline of the polygons transparent.  

Next, select grasslands from the landcover theme using the query tool.  

48)  How many polygons exist in the land cover data set?

49)  Of these, how many polygons are grasslands?

Turn off all themes except landcover and finalfiretowers.  Recall that you want to select sites are located near major stands of grassland.  

50)  Pick the three sites that, in your judgment, make the best sites for the fire towers.  For each, Indicate its UTM coordinate, distance from St Francis, and direction from St Francis:

Site       UTM                       Distance from St Francis     Direction from St Francis

51)  Justify your reasons for selecting the three sites for the fire towers.

52  Create a layout for printing that contains the results of your study sites along with roads and hydrography, as follows:

View —> Layout.  Create your layout.  With the text tool, add your name, date, and change the title of the map to something that reflects what the map displays.

Print the layout.

Save your project.  Close your project and exit ArcView.

52) Summarize in a few sentences what you have learned about locating fire towers in this lesson.  

53) Summarize in a few sentences what you have learned about GIS in this lesson.

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