Streams and Flood Plains

Flow of Freshwater-2.0

by Restie Carullo

​Earlier, you learned that rivers and streams erode rock and soil. However, rivers also carry this loose rock and soil to new places.

Multiple Choice

Rivers can help to form new land

through deposition

• True

• False

​Sediments

​

​The rock and soil that a river erodes from the land

move downstream in the river’s load. Material, such as rock and soil, that is deposited

by rivers and streams is called sediment.

Rivers can help to form new land through deposition. Deposition is the process in which material is laid down, or dropped.​

Multiple Choice

Using the image, where do you think erosion occurs?

• erosion happens along outside of the bend where water flows quickly

• erosion happens along inside of the bend where water flows slowly

Multiple Choice

Deposition occurs along inside the bend where water flows _______.

• slowly

• quickly

​Placer deposits

​Heavier minerals such as gold, can be carried by fast-moving rivers. In places where the rivers slow down, the heavy minerals may be deposited. This kind of sediment is called a placer deposit.

​Delta vs. Alluvial Fans

​When the river enters the ocean, it deposits its load under the water in a fan-shaped pattern called a delta. The river deposits can build up above the water's surface to form new land and build new coastline.

​Delta vs. Alluvial Fans

Rivers and streams can also deposit their loads on dry land. When a fast-moving stream flows from a mountain onto flat land, the stream slows down quickly. As it slows down, the stream deposits its rock and soil in a fan-shaped pattern known as alluvial fan.

​Why do rivers and streams flood?

​A flood happens when there's too much discharge for the channel to hold, that it flows over the sides of its channel.

​

During the flood, the land along the sides of the stream is covered in water. The stream drops its sediment on this land, which is called a flood plain.

​

​Humans try to control flooding by building barriers around streams. One kind of barrier is called a dam.

Multiple Choice

Floodplains are good areas for farming because flooding brings new soil to the land.

• True

• False

​Groundwater

​Some of the earth's freshwater is found underground.

​Groundwater can also cause weathering, chemical weathering by dissolving rocks. Weathering by groundwater can form large caves.

​

What structures can groundwater form?

1. ​Stalactites-minerals that hang from the ceiling

2. Stalagmites-minerals that form from cave floor

3. Dripstone Column-when stalactite and stalagmite form

4. ​Sinkhole-it happens when the cave collapses

​dripstone column

sinkhole

Multiple Select

The following are structures that groundwater form EXCEPT:

• stalactite

• stalagmite

• dripstone column

• sinkhole

• mountain