Answer to Map #83

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Answer: This week’s map was a dot map depicting the 100 tallest dams in the world.

There are lots of different ways to rank dams. We could have chosen to highlight the largest dams, which are those that use the most material (concrete or whatever else) to block a river. Or we could have chosen to map those dams that generate the most electricity. Or those that displace the most water and form the largest reservoir. Instead, we opted for the tallest dams. The tallest dams are often those in fairly mountainous areas, and many of them have been built recently. Many more dams that are currently under construction could enter the top 100 upon completion.

At present, the world’s tallest dam is the 1,001-foot-tall Jinping-I Dam in China’s Sichuan Province, which was completed in 2013. The Jinping-I Dam is one of many dams on the Yalong River, a tributary of the Yangtze. Thanks to China’s infrastructure-building spree, the main channel of the Yangtze is also home to a great number of large dams. One such dam is the Three Gorges Dam, which is the world’s largest dam in terms of how much hydroelectric power it produces—but it isn’t all that tall. At 594 feet in height, it’s well down our list. But it is in the top 100, so it’s on our dot map.

One interesting feature of this map is that it contains dots on all six populated continents. That’s because dams are useful in lots of different environments. It’s also worth noting that there are many large dams in developing countries. That fact reflects the importance that many countries place on massive infrastructure projects.

One such massive project is the construction of the Grand Ethiopian Renaissance Dam on the Blue Nile. Thursday’s hint mentioned the controversy over this dam. If completed, the dam would provide much needed hydroelectricity to Ethiopia, but it could have unpredictable consequences downstream. Both Sudan and Egypt have expressed concerns about the project, but it has been Egypt that has been most outspoken. On several occasions, the Egyptian government has even threatened military action to prevent construction of the dam. The dispute raises some interesting questions about what right one country has to interfere with a river that crosses international boundaries.

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