Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth  

An Introduction to Land Cover Changes over Time This lesson plan builds on the lesson plan on ‘Understanding Land Use and Land Cover Using Google Earth’. Please refer to it in terms of definitions on land use and land cover. The terms land use and land cover is not synonymous. Land use is defined as human use of land. In other words it refers to the economic use to which land is put. Examples include parks, medium density residential areas, and industrial areas. Land cover is different. Land cover refers to the material in contact with the Earth’s surface. An area designated as a park on a land use map, for example, may include several land covers such as areas of deciduous or evergreen forest, or fields of grass (herbaceous vegetation). Another example is your school. On a land use map, your school may be shown as an “institutional use” or “educational use.” Within the boundaries of your school’s property, you may be able to identify several land covers including forest areas, grassed fields, and impervious surface (your school building(s), parking lot, sidewalks, etc.). Many land use, land cover, and land use/land cover classifications have been developed by federal, state, and local government agencies. For example, the U.S. Geological Survey used a modified version of what is referred to as the Anderson classification system for the 2001, 2006 and 2011 National Land Cover Data (NLCD) classification scheme. The image below shows the Anderson classification system. 11 Open Water 12 Perennial Ice/Snow 21 Developed, Open Space 22 Developed, Low Intensity 23 Developed, Medium Intensity 24 Developed High Intensity 31 Barren Land 41 Deciduous Forest 42 Evergreen Forest 43 Mixed Forest 1 51 Dwarf Scrub 52 Scrub/Shrub 71 Grassland/Herbaceous 1 72 Sedge Herbaceous 1 73 Lichens 1 74 Moss 81 Pasture Hay 82 Cultivated Crops 90 Woody Wetlands 95 Emergent Herbaceous Wetlands 1 Alaska only.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   The NLCD 2001, 2006 and 2011 are displayed using the above legend. •

The image below shows the 2011 NLCD Land Cover map for the 48 continuous states:

In addition to the NLCD 2011 land cover map, the lesson plan will further demonstrate how to display the impervious surface and tree canopy data in Google Earth. •

Impervious surfaces are mainly artificial structures, such as pavements

(roads, sidewalks) that are covered by impenetrable materials such as rook tops, asphalt. Below is shown the map where impervious surface areas are shown in red. 2011 NLCD Impervious Surface Map.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   •

Canopy data represents the tree canopy cover for the US. Green areas show tree cover for the whole US. 2011 the NLCD Canopy Layer.

Lesson: An Introduction to Land Cover Changes over Time Learning Objectives: The overarching goal of the US Land Cover Data Set is to promote the awareness of the trends and use of spatial information about the impact of changes occurring to the land cover and its influence on human health and the environment. Understanding perspectives of space-based observations will help students to monitor changes on our planet to develop strategies to manage natural resources, and sustain human wellbeing. Displaying an extensive collection of historical and current satellite imagery is enabling students to observe and document the significance and consequences of changes in the environment, many of them caused by human activity, over time. Students can better understand the long-term changes to our planet by seeing and understanding how humans (and climate) are modifying the land's resources. Students will begin this lesson with locating land cover data sets over different time periods online, import these data sets into Google Earth to observe environmental and human-made changes to our planet’s land cover. Analyzing these changes will guide students to better manage environmental resources at all geographical scales, from local to global level. Students will learn to: • • • • •

Distinguish between different land cover types Identify areas on a map, which do not allow water to flow through and which surface areas are penetrable by water Discover the locations of tree cover in the US Consider effects of environmental changes Develop strategies to positively influence these changes.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   Teacher Prep time: One hour is required for those who are new to Google Earth. Fifteen minutes is required, to review the lesson, for those with a working knowledge of the software and an understanding of land cover classification. Prerequisite: Google Earth Lesson 2, “Understanding Land Use and Land Cover “ Class Time Requirement: 50 minutes Materials needed: Windows or Mac computer with Internet connection and Google Earth 4.3 or higher installed Teacher Prep Instruction: Unblock and install Google Earth for your class, if needed. Explore the following website to familiarize yourself with the content http://www.google.com/earth/learn/ Classroom Instructions: Access the following website to familiarize yourself with the concepts of Land Use and Land Cover - http://landcover.usgs.gov/usgslandcover.php

National Land Cover Data Base (NLCD) – is a 20-class land cover classification scheme. It is comprised of three different elements: land cover, percent tree canopy density and percent-developed impervious surface. Impervious Surface – are mainly artificial surface covered by impenetrable materials (asphalt, concrete, etc.). Canopy- is the layer of stems of trees, leaves, branches that cover the ground when viewed from above. KLM – stands for ‘keyhole markup language’, a file format used to display geographic data in location-based programs such as Google Earth. Those files are often distributed in zipped format as .kmz files.   Now you will learn the procedure to import and display the NLCD data sets (land cover, impervious surface, and tree canopy layers) in Google Earth: 1.) Visit https://raster.nationalmap.gov/arcgis/rest/services/LandCover

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth  

2.) Select “LandCover/USGS_EROS_LandCover_NLCD (MapServer)” to access the NLCD data sets.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   3.) To download individual data files for individual display and analysis you have to scroll to the bottom of the website to “Supported Operations:” and select “Generate KLM”.

4.) The following window appears:

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   5.) In the “Document Name:” field enter the description of the data set you want to downloading, e.g. NLCD_2011; NLCD_2006; NLCD_2001; or NLCD_1992. 6.) In the “Layers:” section select the data set you would like to display in Google Earth. Select only one data set and no sub-data sets. To display the NLCD 2011 data files check only the NLCD_2011 check box. 7.) Under the “Layer Options” choose the “Each layer as a separate image” and click on the “Generate KML” button. Your website browser screen should look like the one below:

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   8.) A zipped kml (.kmz) file containing the various data sets listed in the subcategory of each NLCD data set will now be located in the download folder on your computer, as shown in the image below.

9.) Now start Google Earth on your computer. 10.) Select “Open” from the “File” menu located in the main menu bar of Google Earth. 11.) To display the data sets select the .kmz file located in your download folder, and double click to automatically upload into Google Earth. 12.) The .kmz file contains all NLCD data sets of a specific year, which will be located under “My Places” in “Temporary Places”. By selecting the folder all data sets will be displayed at the same time on the globe, see image below.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   13.) Choosing the drop down menu you will be able to select only the data set you want to display at a time. For example select the “Impervious_Surface_2011”, as shown below.

14.)The selected layers should have a checkmark in the checkbox ( the “My Places”, “Temporary Places” panel.

) next to them in

Note: Checking a layer’s checkbox will either add the layer to the globe or remove the layer from display on the globe. 15.) If you wan to display the tree canopy layer instead of the impervious surface you have to check “Canopy_2011_CONUS” in the “My Places”, “Temporary Places” folder and uncheck the “Impervious_Surface_2011”. You will now be able to see the tree canopy displayed on the map, see image below.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   16.) To see the “Impervious Surface” layer once again; click the “Canopy” checkbox. This will “uncheck” the checkbox and remove the “Canopy” layer from the globe. Now select the “Impervious Surface” checkbox to display the data layer. 17.) In the “Search” panel on the top left side of your screen, type the name of ‘your city’ and click the “Search” Button. The camera--your point of view--should zoom in to your hometown. Wait a few seconds after the camera stops moving for the image layers to refresh to fit the new zoom level. 18.)Highlight the “Impervious Surface” layer by clicking on the label. 19.)Use the “Transparency Adjustment” slider to increase the transparency of the layer. The slider’s default position should be all the way to the right – this means the layer is completely opaque. Click and hold the slider and drag it all the way to the left. The “Impervious Surface” layer should now be completely transparent.

20.)Click and drag the slider to the middle of the slider bar, which should be somewhere between completely transparent and completely opaque. You should now be able to see the satellite image below the displayed “Impervious Surface” data layer, see below.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   21.)To add the “Canopy” layer back to the globe, click the empty checkbox next to “Canopy” and the layer will be added to the globe as well. You will now be able to see the added “Canopy” layer on top of the slightly transparent “Impervious Surface” layer (see screenshot below).

Note: The order of the layers in the ‘My Places’ panel does NOT indicate the order of the layers on the globe. Google Earth has a slightly different behavior than you may be used to with other GIS programs. The layer checkbox that you most recently checked will become the top most layers on the globe. To change the order of the layers, try this: a. Uncheck both layer checkboxes. Neither layer should be visible on the globe. b.

Check the “Impervious Surface” checkbox. You should now be able to see the “Impervious Surface” layer on the globe.

c.

Slide the “Transparency Slider” to the middle to create a slightly transparent impervious surface enabling you to see the satellite image below.

d.

Check the “Canopy” checkbox. You should now see the ‘”Canopy” layer on top of the impervious surface layer.

e.

Uncheck the ‘Impervious Surface’ checkbox to only see the “Canopy” layer displayed.

f.

You can add more layers on to the map, e.g. the “Land Cover” data layer.

g.

The most recently selected layer is displayed as the top most visible layer.

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   Note: The default Google Earth satellite imagery is ‘the best available imagery’, but is not always the most up-to-date imagery that you have access to. In this lesson plan, the United States Geographical Survey (USGS) Landsat 8 satellite takes the default satellite imagery displayed on the globe. Since 2015 Google Earth includes access to historical imagery taken by the Landsat series of the USGS, which includes imagery from the past as well as the most up-to-date imagery for most locations. To find out if any changes have taken place over the years, access the historical imagery tool by selecting “Historical Imagery” in the “View” menu bar. The historical data slider will now be visible in the top left corner (see screenshot below). Now you will be able to discover not just at what point in time the imagery was taken but also the organization that took the imagery. The information is displayed the middle at the bottom on the screen. Additionally select “Scale Legend” in the “View” menu bar to determine the map scale of the data displayed, located on the right side bottom corner.

Classroom Questions: • • • • • •

What land cover types are around your school in 2016? If any, what changes occurred to the land cover type over time. What is the definition of impervious surface and the canopy data? Is there a correlation between the impervious surface location and the tree canopy? What are potential reasons influencing this change? What are potential the impacts of the changes to human health and to the environment? What are ways to mitigate these changes?

 

Lesson Plan 3 –Viewing Land Cover Data Sets Using Google Earth   Resources Get Land Cover Data: http://landcover.usgs.gov/landcoverdata.php 2001 National Land Cover (US EPA Multi-Resolution Land Characteristics Consortium) http://www.epa.gov/mrlc/nlcd-2001.html Anderson Classification System http://landcover.usgs.gov/pdf/anderson.pdf Land Cover Trends (U.S. Geological Survey) http://landcovertrends.usgs.gov/main/classification.html The USGS Land Cover Institute http://landcover.usgs.gov/uslandcover.php Import NLCD data sets: http://raster.nationalmap.gov/arcgis/rest/services/LandCover/USGS_EROS_LandCover_ NLCD/MapServer Discover and download NLCD data by region http://www.mrlc.gov/viewerjs/