How does nationalism cause war?

it would A

Floods on the Mississippi River are getting more frequent and more severe. But scientists warn that the infrastructure meant to protect towns and farms against flood waters is making the problem worse.

A series of analyses have helped confirm what engineers have posited for more than a century: that earthen levees built along the river are increasing flood risk for everyone, and especially hurting those who live across from them.

"When a new or larger levee is built there is often hew and cry, and if there isn't, there should be," says Nicholas Pinter, a geologist and the associate director of the Center for Watershed Sciences at the University of California, Davis.

"What you're doing in many cases is taking a flood plain out there — it can be 5 [or] 6 miles wide — and you're forcing the water that would otherwise spread across that area to go through a narrow passageway." As the passageway gets narrower, the water flows faster and higher.

The resulting floods are more severe than they would have been without the levees, which then drives people to build more levees, driving a "hydrologic spiral" of flooding, levees, more flooding and higher levees.

Explanation:

for more info go to https://www.npr.org/2018/05/21/610945127/levees-make-mississippi-river-floods-worse-but-we-keep-building-them