Passage: The desert is crossed by the second largest irrigation canal in the world, the Karakum Canal, which brings water from the Amu Darya to southern regions of the desert. Construction on the canal was started in 1954 and completed in 1958. It is 1,375 km in length, and carries 13-20 km³ of water annually. Leakages from the canal have created lakes and ponds along the canal and the rise in groundwater has caused widespread soil salination.

Question: What does it carry?
13-20 km³ of water