I don’t see anything, (which of these?)
Shi Huangdi was an effective leader because he was the first Chinese emperor that managed to unite the northern China and responsible to the first development of China's great wall.
Not only that, he is also the one that introduces China to the usage of money as a medium of transaction.
Answer:
one must be a citizen of Washington
The correct answer is - Large numbers of migratory birds;
The number of the migratory birds has always been pretty high and it hadn't resulted in the drying up of the Ogallala Aquifer, not to mention that those birds can not even reach that water because it is underground. Also, the number of the migratory birds have been steadily lowering, so even if they were using that water for drinking, it wouldn't have caused the drying out.
The Ogallala Aquifer has started to dry out because of numerous reasons, with the usage of its water for irrigation being the prime reason. The droughts have become longer, and the temperatures little higher, while the rainfall slightly smaller, so all of that affected the reserves of water in the aquifer negatively.