The Black Death was a plague the spread across medieval Europe in 590CE to 1500CE. It was an infection caused by rats and then spread by fleas. The rats were carrying a lot of germs and bacteria at the time so a flea would bite the rat and then would and bite a person.
The average life expectancy of a dam is 50 years, and 25% of the dams in the Army Corps of Engineers National Inventory of Dams are now more than 50 years old.This number is projected to increase to 85% by the year 2020.he Glen Canyon Dam supplies over 5 million people with power (Glen Canyon Dam Adaptive Management Program, 2007). These two dams also have the capacity to store 32,471,000 acre-feet and 27,000,000 acre-feet of water, respectively. In order to harvest hydropower however, dams must be built.
This is a list of the tallest dams in the world over 135 m (443 ft) in height. Currently, the tallest dam in the world is the Jinping-I Dam, an arch dam in China at 305 m (1,001 ft) high. The tallest embankment dam is the 300 m (984 ft) high Nurek Dam in Tajikistan which is also the second tallest dam in the world. For gravity dams, the tallest is the 285 m (935 ft) high Grande Dixence Dam in Switzerland. When completed, the 335 m (1,099 ft) tall Rogun Dam also in Tajikistan could be the tallest, depending on the chosen design.