Author Question: What causes the subsidence that sometimes accompanies groundwater use? What will be an ideal ... (Read 127 times)

awywial · **on:** Jul 15, 2018

What causes the subsidence that sometimes accompanies groundwater use? What will be an ideal response?

Question 2

Why does the Leaning Tower of Pisa lean? Is it likely to lean so much it will someday fall over? What will be an ideal response?

amandalm · **Reply #1 on:** Jul 15, 2018

Answer to Question 1

As the water is withdrawn from pore spaces in poorly consolidated sedimentary materials, the water
pressure between grains is reduced, the weight of the overlying materials causes the grains to pack
more closely together, and the materials become compacted, resulting in subsidence of the ground.

Answer to Question 2

One reason the tower leans is groundwater subsidence. It began to lean shortly after construction due
to compaction of the ground beneath it. The tilt increased in the 1960s as the community withdrew
groundwater from the underlying aquifer. The tower is not likely to fall over because the withdrawal of
groundwater is now well regulated and the base of the tower has been stabilized, so the tower should
stand for several more centuries