Corrasion, otherwise known as abrasion, is the grinding of rock fragments carried by the river against the bed and banks of the river. This action both widens and deepens the channel. The power of the grinding is especially powerful in floods when large fragments of rock are carried along the river bed eroding the bed and the banks.	Attrition is the knocking of rock fragments in the water against one another. The fragments are broken into smaller pieces and become smoother along the process.
Solution, also known as corrosion, is the process by which river water reacts chemically with soluble minerals in the rocks and dissolves them. For example, when a river stream flows over an area of limestone (calcium carbonate), it erodes the limestone by reacting chemically with it and dissolves it.	Hydraulic action is the breaking down of rocks and dragging them away from the bed and banks by the force of the running water itself. When water from a fast moving stream enters cracks in a rock, the force breaks up the force into pieces.

Some rivers have greater volume than others. There are four factors that influence volume.

The presence of vegetation affects the rate at which water is intercepted and is able to infiltrate the ground. If an area is covered with vegetation, the vegetation will intercept the rain and allows some of it to infiltrate into the ground. As a result, there will be less water as surface runoff into the river and so the volume of water into the river will be lowered. On the other hand, in an area with no vegetation, there will be no interception and little infiltration into the ground. This will result in more water as surface runoff into the river and so the volume of the water is higher than that of a vegetated area.

The permeability of rocks is determined by the size of the pores between the rock particles. If the rock has small pores, water cannot easily infiltrate into the rock and this means that the rock is impermeable. On the other hand, if the rock has large pores, water can easily infiltrate and thus the rock is permeable. When water flows through an area of impermeable rock,little water infiltrates the ground, as a result there is high surface runoff and leads to a high volume of flow of water.

A larger drainage basin will have a greater volume of water. This is because there is a greater amount of tributaries bringing water to the river resulting in a higher surface runoff.

Drainage Basin refers to the area drained by a river and its tributaries.

Climate:

The amount of precipitation and temperature affects the volume of river. During dry season, a river channel may be almost empty therefore the volume is low. During the wet season, the volume will be high and water may overflow the channel and flood the surrounding land.

Temperature also plays a part in influencing the volume of rivers. When the temperature is high, there is more evaporation and transpiration which reduces the amount of water in the river.

The three factors that influence the velocity of a river are the river gradient
,channel roughness and channel shape. Click on any of the sections above to begin.

A river flowing down a steep slope or gradient has higher velocity than one which flows down a gentler gradient. For example, the speed of flow in a river that plunges down a steep slope in the form of a waterfall is much higher than the speed of flow in a river that winds down a gentler slope.

In figure A, the channel is smooth while that in figure B is rough or uneven with boulders on the river bed as well as rocks that protrude out from the bank. A river that flows through such a river has to overcome such obstacles and therefore there will be more friction and the velocity of the river is reduced.

A river uses its energy to carry or transport eroded materials such as mud, sand, boulders and dissolved materials. These materials are called its load. River transport their load by four processes. These processes are traction, saltation, suspension and solution.

Large particles such as gravel and coarse sand are lifted and dropped along the river, so they
bounce along the river bed in a series of bed.

Larger particles like pebbles and boulders roll and slide along the river bed.

Dissolved materials containing minerals like calcium and sodium are carried in the water. Trying to look out for these type of load in a river? Too bad, they cannot be seen by a naked eye.

Smaller particles such as clay, silt and fine sand are carried along without contact with the river
bed. Materials carried in suspension usually forms the greatest part of the total river bed.