Can human actions alter water resources?

Step 1: Go to the ArcGIS Online map, Down to the Last Drop, and explore the map.

Step 2: Examine the recent view of the Aral Sea in Central Asia.

Step 3: With the Details pan visible, click the button, Show Contents of Map.

Step 4: Click the checkbox to the left of the layer name, Aral Sea, 2000 (image) & 1960 (black outline).

Step 5: The image is from 2000 and the outline shows the 1960 extent of the sea before humans began to alter water flow to the Aral Sea.

• What physical changes can be seen in the Aral Sea since humans altered the water flow?

Where are other lakes and rivers that are drying up due to human actions?

Step 6: Click the Bookmarks button. Select one of the other location bookmarks for a closer examination.

Step 7: Click the map marker to view detailed information about human alterations to this water resource.e

• What human events have caused changes in water resources.
• What natural events have caused changes in the water resource?

Why is the water to the Aral Sea decreasing?

Step 8: Select the Bookmark, Aral Sea Region.

• Do both rivers reach the Aral Sea?

Step 9: Turn on the layers Aral Sea Watershed Dams and Irrigated Land in Aral Watershed.

• Do dams or canals have the most significant impact? Zoom in to irrigated areas to view canals.
• What factors could influence the placement of the dams and canals?

How would the Aral Sea drying up affect the surrounding areas?

Step 10: Turn on the layer, Aral Sea Dust Impact. Zoom out to see the impact area.

Step 11: Increased dust and salt storms sometimes send dust 500 km from the Aral Sea.

• The reason why dust and salt storms occur is that the dry bed of the salty sea has no vegetation.
  
• What environmental, economic, and health effects might this have on the surrounding areas? Look closely at the areas within the buffer.

How has human alteration affected the Colorado River?

Step 12: Press the button, Bookmarks. Select the Colorado River bookmark.

Step 13: Turn on the layer, Lower Colorado River Basin Dams and Canals.

Step 14: Zoom in and out to identify human alterations and causes.

• What are some similarities and differences between the effects of human alterations on the Colorado River?