Aral Sea (Ecological Investigation)

 

The image on the right is an aerial view of the Aral Sea. What was once the fourth largest lake in the world has dropped to sixth place. Over 30 years ago the two major rivers that supplied the Aral were diverted to irrigate Central Asian farm land.
This has led to a drastic shrinking of the sea with large areas of the lake bed supplanted by shifting sand. The lake’s salt concentration has increased from 10% to 23% which has led to a destruction of a once flourishing fishing industry. There have been drastic climatic changes because of the reduced influence of this body of water on the weather. Lastly, there have been severe changes in the health of the people surrounding the lake.

Show ImageJ application.

Go to File, Open Samples and open the images RegMap and Aral. On the regional map the lake lies within the boundaries of the republics Kazakhstan and Usbekistan which further complicates environmental action

Close the RegionMap and Aral Open the stack Aral Peninsula.(A colored view of this stack is shown below.)You can move forward and back in this stack by using the < and > keys at the bottom of the stack. In these two views you can see that you are looking at the northern end of the sea. Notice the obvious decrease in sea size between the 1973 and the 1987 views. This is largely due to a diminished supply of water from the two rivers feeding the lake. Notice the peninsula extending down from center in the two views.

Close Aral Peninsula and Open AralStack You may have to use the Magnifier tool to see all of the image. We will use the straight line tool to measure this increase in the peninsula.

There is a calibration scale that says 0 to 40 km (kilometers) at the top of the 1973 image. Take your straight line tool and click on the left side of this scale and draw the line to the 10 km. mark on the scale. Go up to Analyze, and click on Measure. (You should get a reading between 30 - 40) Now go to Analyze, Set Measurements and the only boxes selected should be Perimeter and Area and Limit to Threshold. Click OK and then go to Analyze, Set Scale. Enter the distance in pixels that you got, (It is 40 in the example given) and then enter 10 for known distance and km for kilometers. Click OK Using your straight line tool click where the peninsula begins and draw a line down to the tip. Then go up to Analyze and select Measure. Your result will be in kilometers. Do the same thing with the 1987 map. Determine the distance increase that has occurred between 1973 and 1987.

 

Put your answer in the Results Section.

Measuring the change in volume in this area of the Aral Sea.
Move to the 1973 image in AralStk. Go to Image, Adjust and Threshold. You will see two slide bars. Adjust the top slide bar to 200 and the bottom slide bar to 255. (What you have done is to select everything with that pixel density out of 256.)

Select the Wand Tool and click on an area of the sea near land until you see a yellow line surrounding all the red. Now do Analyze, Measure. The area of everything that you have selected in RED has been measured in square kilometers. Move to the 1987 image. It should also be selected RED and repeat the clicking. Do Analyze, Measure again and you should have a new reading. Is it smaller or larger than the previous one. Does this make sense?

 

 

Put your answer in the Results Section.


 Results:

(You can also Go to File, Open Samples and Open the image Results which is a copy of this Results section. While this page cannot be printed out - at this time - it can be saved as a JPEG file to your desktop. You can then open it with any graphics program,type out the answers and then print it out from your program.

You can also enter the results on this image using the Text Tool. To do this first go to Edit, Options, Fonts and select something like Geneva - 12 pt - Bold. Then click on the Results Image in the answer space and draw out the yellow rectangle that appears and start typing. When you are finished go to Edit and Select Draw. What you have typed should now be present.)


1. What do you get for an increased length to the peninsula?




2. Aral Sea water area change.

1973 Area in square kilometers
1987 Area in square kilometers
   


Acknowledgments:

(You may want to visit these WEB sites for further educational/technical information.)

Center for Image Processing in Education http://www.cipe.com

United States Geological Survey http://edcwww.cr.usgs.gov/earthshots/slow/tableofcontents

People and the Planet http://www.oneworld.org/patp/pap_aral.html

Federation of American Scientists http://www.fas.org/nuke/guide/russia/facility/cbw/vozrozhdenly.htm

The German Remote Sensing Data Center http://www.dfd.dlr.de/app/land/aralsee/

 

Notes:

1. There are a number of directions that you can take with this exercise on the Aral Sea. The United States Geological Survey site (Listed above) and the The German Remote Sensing Data Center has many of the images found in this exercise. Students may want to read the posting at the People and the Planet WEB site. This site has a particularly good review of the enormous problems posed by the Aral Sea contamination.

2. The Federation of American Scientists WEB site introduces a whole new dimension to the Aral Sea problem. The image on the right shows Vozrozhdeniye Island in the Aral Sea. (Also known as Renaissance or Rebirth Island) This island was used for decades to test biological warfare weapons. This included anthrax, plague and smallpox. I would recommend reading Biohazard which was written by Ken Alibeck (former head of the Soviet germ warfare program.)

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