A stream table with points labeled A and B. A: Stream of water moving from left to right. B: Larger body of water where the stream ends.

Question

Suppose a block of wood is placed under the left edge of the table.
How would the new slope affect the rate of erosion?

Where would most of the sand be deposited?

Answer 1

When a block of wood is placed under the left edge of the stream table, it creates a slope that directs the flow of water from the left (point A) toward the right (point B) more steeply.

Effect on the Rate of Erosion:

1. Increased Erosion Rate: The steeper slope will typically increase the velocity of the water flow. Faster-moving water has more energy, which allows it to carry sediment and erode the bank more efficiently. Therefore, the rate of erosion would likely increase as the water flows downhill more rapidly, eroding the streambed and banks along its path.

Location of Sand Deposition:

2. Sand Deposition Area: Most of the sand (and other sediments) would be deposited in areas where the water flow slows down, typically as it approaches point B (the larger body of water). As the stream enters a larger body of water, the flow velocity decreases significantly, causing particles to settle out of the water. This is known as sediment deposition. Areas where the stream widens or where there are bends or turns can also accumulate sand as the flow slows.

In summary, the new slope increases erosion due to faster water velocity and causes sediment to be deposited in slower-flowing areas, particularly at the mouth of the stream where it meets the larger body of water.