1. Gradient: As a river flows downstream, it typically encounters a decreasing gradient or slope. This means that the riverbed becomes less steep, which allows the water to flow more quickly. The steeper the gradient, the slower the river velocity, and the gentler the gradient, the faster the river velocity.
2. Channel Morphology: As a river flows downstream, its channel morphology often changes. The riverbed may become wider and deeper, which reduces friction and allows the water to flow more freely. The presence of obstacles such as rocks, boulders, and vegetation can also slow down the river velocity.
3. Discharge: The discharge of a river, which is the volume of water flowing through a given cross-section per unit time, also influences river velocity. As a river flows downstream, it often accumulates more water from tributaries and other sources, which increases its discharge. This increased discharge leads to a higher river velocity.
4. Sediment Load: The sediment load carried by a river can affect its velocity. Rivers with a high sediment load tend to have lower velocities because the sediment particles create friction and drag.
5. Human Modifications: Human modifications such as dams, reservoirs, and channelization can also impact river velocity. Dams and reservoirs can slow down the river velocity by creating a pool of water behind the dam, while channelization can increase the velocity by straightening the river course and removing obstacles.
In summary, the increase in river velocity downstream is influenced by various factors such as gradient, channel morphology, discharge, sediment load, and human modifications.
