The U.S. has more than 87,000 dams greater than six feet high (and two million overall). While many dams continue to provide benefits such as flood control, irrigation, and water supply, for other dams the cost of maintenance or the negative effects on communities, fish, and tribes justifies their removal.
Dam owners and regulators decide whether to remove a dam by weighing many factors including: the cost of removal and the ability to replace any lost power generation against avoided long-term maintenance; safety concerns; benefits to endangered fish populations; increased recreational and commercial fishing; and restoration of cultural values of nearby tribes.
By 2020, roughly 70% of dams will be more than 50 years old, inviting us to reconsider the value to the public of long-term investments in this infrastructure.
The Basin System of Irrigation was d<span>eveloped thousands of years ago.
It is now used only in parts of southern Egypt and northern Sudan. It only supports one main crop because it is dependent on the annual flooding of the Nile.
TRUE :)</span>
Answer:
Option C. Deep ocean canyon
Explanation:
The Mariana Trench is an example of a deep ocean canyon
<span>Air masses interact with cyclones because areas of high pressure go into areas of lower pressure causing them to form. Hope this helps!</span>
