This map shows one example of user output from the chapter. Different colors might be used to mark the land, and areas for each range of years might be slightly different due to personal differences in judging which areas are land versus water. In some locations, the images appear to show where dredging procedures have begun, but not ended. Areas such as these may appear categorized in either range of dates.
After completing this chapter, students will be able to:
- create a movie (animation stack) from a set of registered images;
- flip between the stacked images to identify change over time;
- mark areas that have changed between successive images; and
- make a key to the color codes used on the final map.
This technique can be used with any set of satellite images or maps that show the same place at the same scale (they are geo-registered) at different times. Such images are referred to as time-series images. Identifying, outlining, and marking areas of change in the images results in a color-coded map that shows the location and geographical extent of change.
Examples of topics that can be documented using this technique include deforestation, urbanization, changes in shorelines, and flooding.
The true-color satellite images of Earth used in this chapter are very similar to photographs taken by a digital camera. The main difference is that the camera was held very far away from its subject! With some prompting, students who have mastered basic map-reading skills or have the ability to understand a top-down orientation should be able to interpret features in these images based on their colors and shapes. To understand the main point of this chapter, students must also be capable of considering how features at this location have changed over time.
NASA's Landsat 7 Education Page offers learning resources on understanding satellites and remote sensing for students from grades 2-16.
The following National Science Education Standards are supported by this chapter:
- Use appropriate tools and techniques to gather, analyze, and interpret data. The use of tools and techniques, including mathematics, will be guided by the question asked and the investigations students design. The use of computers for the collection, summary, and display of evidence is part of this standard. Students should be able to access, gather, store, retrieve, and organize data, using hardware and software designed for these purposes.
- Communicate scientific procedures and explanations. With practice, students should become competent at communicating experimental methods, following instructions, describing observations, summarizing the results of other groups, and telling other students about investigations and explanations.
- Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion.
- Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.
- Scientists rely on technology to enhance the gathering and manipulation of data. New techniques and tools provide new evidence to guide inquiry and new methods to gather data, thereby contributing to the advance of science. The accuracy and precision of the data, and therefore the quality of the exploration, depends on the technology used.
- Interactions among the solid earth, the oceans, the atmosphere, and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years.
The following U.S. National Geography Standards are supported by this chapter:
- How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective
- How to analyze the spatial organization of people, places, and environments on Earth's surface
- The physical processes that shape the patterns of Earth's surface
- How human actions modify the physical environment
- Case Study: 5 minutes
- Part 1: 20 minutes
- Part 2: 30 minutes
- Part 3: 30 minutes
Historical Landsat Data Comparisons, Illustrations of the Earth's Changing SurfacePublished by the U.S. Department of the Interior, U.S. Geological Survey EROS Data Center. March 1995. Available from EROS Data Center, Sioux Falls, SD, 57198, Telephone 605-594-6151.
This 46-page color booklet shows 17 printed pairs of before-and-after images from around the world. Captions written by scientists describe changes in the scene. References and Landsat Scene ID numbers are provided, so students can access the original data to pursue their own exploration of the issues illustrated by the image pairs.
Hong Kong and the Pearl River Delta As Seen from Space ImagesEdited by Kam Nin Au and Kamlesh Lulla. Geocarto International Centre, P.P.O. Box 4122, Hong Kong. 1997 ISBN: 962-8226-01-0.
This book contains space images from a variety of satellite instruments accompanied by concise notes and captions, plus seven well-illustrated articles written by experts who specialize in extracting scientific information from space imagery.