15 Questions
What is the base level of a stream?
The point where stream channel erosion does not occur
What is the velocity of a stream?
The speed at which water flows through a stream channel
Why does the velocity of water decrease along the stream bed and banks?
Because of larger rocks obstructing the flow
How does the power of running water to erode the channel change with decreasing velocity?
Decreases
What are the two types of base levels in a stream?
Ultimate base level and local base level
Why does water flow with less energy at the base level of a stream?
Reduced velocity and energy
What hinders the flow of water in a stream at the base level?
Larger rocks
What is the ultimate base level in terms of stream erosion?
The sea level
What describes the local base level's impact on stream erosion?
Reduces the energy for erosion
What effect does high velocity water flow have on stream channel erosion?
Results in sediment removal
Which scenario would likely lead to more sediment deposition on a stream bed?
Still or calm water
How do dams influence sediment deposition in streams?
Facilitate sediment accumulation
Which of the following is NOT an example of a local base level?
A river
How does lowering the base level affect stream erosion?
Accelerates channel cutting
Why does still or calm water at a base level result in lesser channel erosion?
Due to low water velocity
Study Notes
Base Level of a Stream
- The base level of a stream is the lowest point to which the running water can flow or a channel can erode.
- Stream channel erosion does not occur below the base level.
Velocity of Stream Water
- The velocity of stream water is the speed at which water flows through a stream channel.
- It is measured in feet per second (ft/s) or meters per second (m/s).
- Water flows with the greatest velocity and has high energy near the surface in midstream.
- Velocity decreases along the stream bed and banks due to friction.
- Velocity shares direct proportionality with the energy of the water flow.
Types of Base Level
- There are two types of base levels: the ultimate base level and the local base level.
- The ultimate base level is the sea level, which is the height or altitude of the ocean's surface.
- The local base level is the lowest level where the stream water gets stalled or stuck for a period of time.
Base Level Effects
- The velocity of running water and its power to erode the stream bed share direct proportionality.
- High velocity and greater energy cause erosion of the stream channel by carrying away sediments.
- Less velocity and diminished energy lead to deposition of sediments.
- Still or calm water does not cause erosion of the stream bed.
Examples of Base Level
- The ocean is the ultimate base level.
- A lake, a dam, and a waterfall are examples of local base levels.
- A lake becomes the temporary base level when a stream drains into it.
- A dam is constructed to hinder the natural flow of water, causing deposition of sediments within the reservoir.
Learn about the base level of a stream, which is the lowest point where water can flow or a channel can erode. Understand its significance in stream erosion and how it affects the velocity of water flow in the stream.
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