Fluvial Processes and Landforms Flashcards
What is stream erosion?
Running Water removes material from the Earth.
It does so by 3 processes
1. Hydraulic: sheer force pulls particles from the stream bed
2. abrasion: particles carried by the stream hit other particles, knocking them out of place.
3. Corrosion: Chemical processes like hydrolysis dissolve rock material.
What is Stream Transportation?
Describes the amount of material a body of water can hold, known as stream load.
Stream load has 3 components:
1. dissolved load, composed of soluble stuff.
b. suspended load, fine clay and silt that doesn’t sink in calm water.
c. bedload, rocks sand, gravel, and other high-density material moved by flow of the water (saltation) or dragged on the stream bed (traction).
What is Stream Deposition?
Sediment that settles out of the stream, accumulating in certain areas.
There are three types of stream deposition:
1. Alluvial Fans: mountain and hill bases, flat areas that the stream force cannot overcome.
2. River Deltas: Mouths of rivers deposit sediment when they connect to lakes and oceans, which form the deltas.
3. Bars and Point Bars: sediment accumulates in a river channel. A point bar is the outer curve of a meandering stream, where the stream has less energy and therefore a lower stream load.
What is stream load?
Stream load is eroded material carried by a stream’s flow. It has 3 parts: the dissolved load, the suspended load, and bed load.
What are recurrence intervals, and how are they used to
What are the four types of stream channel patterns?
Straight, sinuous, meandering, and braided channels.
What is a straight channel?
Short, and naturally uncommon, indicating strong control by underlying geologic structure. They are also often manmade, such as canals.
What is a Sinuous Channel?
Found in nearly every topographic setting, they gently and irregularly wind, regardless of change in elevaton, but begin to meander when they hit flat land. They possess all types of stream flow.
What is a Meandering Channel?
Found in flat, low-gradient land, they possess a pattern of smooth a tight curves “snaking” across the land that curve in on themselves, cutting, which removes them from the flow. The sediment is often suspended flow.
What is a Braided Channel?
They consist of many interconnected channels stemming from one stream. They become unwoven when a flat stream has a high sediment gradient during a dry season, and begins to rapidly deposit the sediment, which cuts up the stream.
What is lateral erosion?
The method by which valleys widen. As downcutting diminishes as time passes, the stream’s energy is diverted into a meandering flow pattern, water erodes the outside of the curves while alluvium is deposited on the inside of the curves.
What is a base level of a stream?
The lower limit to how much downcutting a stream can do.
What is knickpoint migration?
When there is varied density on the bedrock of a stream, downcutting occurs in some places while it does nothing in others. When the stream bed deepens in some parts, it swirls the water below the denser bedrock, which cuts it below before eroding it downstream.
What is a graded stream?
When a streams gradient adjusts to allow for the same amount of sediment that enters the stream to be transported to the end of the stream, regardless of how that gradient changes in different parts of the stream.
What is headward erosion?
It is a method of valley lengthening. When water flows over the interfluve (the slope between two valleys or bodies of water) the steep slope causes the ewater to rush and cut off part of the interfluve with it, hence pushing th einterfluve farther out and creating more valley.
