For 10 points, name this African river with namesake Blue and White tributaries, the longest in the world.
A growing problem for this river is an increased number of drownings each year during the Sham el Nessim holiday. It is home to a namesake type of monitor lizard that has been listed as an invasive species in the Everglades. One of its tributaries is the Atbara River, which dries up rapidly during the drier period of January to June. An ancient quarry and a staircase-like device used to measure this river's height are found on its island of Elephantine. One major tributary of this river causes the Tis Issat Falls just after originating at Lake Tana. After a massive and well publicized search by Speke, Livingstone, and Stanley, another of its major tributaries was found to flow from Lake Victoria. For 10 points, name this African river with namesake Blue and White tributaries, the longest in the world.
A growing problem for this river is an increased number of drownings each year during the Sham el Nessim holiday.
{Nile} [do not accept "White Nile" or "Blue Nile"]