Question

Please answer the below questions. Thanks.

Kimmswick, Missouri–Illinois
14. What are the gradients of the Mississippi River and of Glaze Creek?

19. Why does Fountain Creek flow some 10 mi south along the floodplain before entering the Mississippi River? What is this feature called?

Answer 1

The gradient of the river is small as the length of the Mississippi River is so great.
The smaller the gradient of the river the slower it moves down its channel.
Thus the present-day gradient of the lowermost area which is 165 km of the Mississippi River is 1.0 cm.

The Congress authorized the FC ACT (Flood Control Act) after excessive and devastating floods in 1936 . So, the corps of Engineers built flood protection across the entire nation.
The corps of Engineers surveyed the American Bottom for the placement of levees in 1945 and designed them to hold flood levels of up to 47 feet to begin construction on them. Over the next two years, the corps completed and constructed the levees along the Mississippi.
To keep Upland Carr Creek, Fountain Creek and Prairie du Rocher Creek from flooding the bottoms, engineers also levied the creeks that flow out of the upland. Building them to the same height which is 47 feet, as the riverfront levees, straightening the corps, shortening and diverting the Fountain Creek to the river.
It left old Fountain Creek to act as a drainage ditch as it meandered to a new pumping station at the levee. The lock is closed to prevent the river from backing up into the ditch when the river is flooded.
Carr Creek and Prairie du Rocher Creek were funneled by the corps through the locks and directly to the river and built a pumping station, but no levee, along Maeystown Creek.
Only two of the three locks opened, which was not adequate. The Corps were asked to break through the riverfront levee and they brought in a barge-mounted shovel to excavate a hole in the levee, five feet deep and 400 feet across.
To release more water from the bottoms, the then commissioners acted against the advice of the Corps and blasted more holes in the levee and enlarged the hole to 1000 feet across and ten feet deep, approximately equal to the size of the breach at Fountain Creek.
The water flowed in from the river and was needed to slow down the surge but as the flood level rose inside the district, it became deep enough to flow out through the intentional break in the levee joining the Mississippi river. So, the Fountain Creek flow nearly 10 mi south along the floodplain before entering the Mississippi River.
This feature is called floodplain feature.