Question

How can erosion affect the water in a river or stream?

Answer 1

Erosion is a natural process in which the materials on the earth like soil are eroded away and carried by natural forces like wind and water. Due to erosion, materials are transported from one place to another. It leads to pollution and sedimentation both on land and water.

Complete answer:
Erosion is a geological process in which the surface of the earth is carried away by the water or wind. The materials from the earth, mainly the top soil is carried away from one place to another and deposited in the land away from the source or in the river or stream.
Agents of erosion: the agents of erosion include rainfall, sea waves in the coastal region, areal flooding, abrasion, landslides, debris flow, ground water process etc.
Effects of erosion:

Land:
1)It leads to loss of fertility of the soil.
2)The land is unable to hold water and can also cause flooding.

Water (Rivers and streams):
1)The erosion leads to increase in pollution and sedimentation in the rivers and streams. The eroded soil or the earthen material moves down to the water bodies and deposits there as sediments and pollutes the water.
2)The clogging of the water bodies severely affects the flora and fauna of the rivers and streams. As a result of which there is a decline in the fishes and other aquatic organisms.

Note: Human activities has increased the erosion by several folds. The roots of the plants hold the soil firmly and prevent it from getting carried away. The erosion can be prevented or minimised by practising terrace farming, afforestation.