explain how streamload and downcutting change over its course

How does the geography of a stream channel affect its flow?

Any change in the geography of the landscape that causes a stream channel to bend or rise (lessening its gradient) will slow the flow of water in the channel. As soon as a stream's velocity decreases, it loses the ability to carry all of its load and a portion will be deposited, depending on how much the stream slows down.

What is a stream load?

The stream load is defined as the solid matter carried by a stream. Streams can carry sediment, or alluvium. The amount of load it can carry (capacity) as well as the largest object it can carry (competence) are both dependent on the velocity of the stream.

What is a stream channel?

The stream channel is the landform, not the water carried in it. The sides of the channel are known as the stream's banks. The bottom is the stream bed. A stream's velocity, or speed, determines its ability to erode, transport, and deposit sediment.

What is a recurring stream?

Recurring ( intermittent) streams have water in the channel for at least part of the year. A stream of the first order is a stream which does not have any other recurring or perennial stream feeding into it. When two first-order streams come together, they form a second-order stream.

What is downcutting and when does it happen?

Downcutting, also called erosional downcutting, downward erosion or vertical erosion is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream's bed or the valley's floor.

How do rivers change from headwaters to mouth?

Discharge increases downstream in most rivers, as tributaries join the main channel and add water. Sediment load (the amount of sediment carried by the stream) also changes from headwaters to mouth. At the headwaters, tributaries quickly carry their load downstream, combining with loads from other tributaries.

What is it called when a stream starts downcutting because the base level changed?

Terraces - Terraces are exposed former floodplain deposits that result when the stream begins down cutting into its flood plain (this is usually caused by regional uplift or by lowering the regional base level, such as a drop in sea level).

Does downcutting make a canyon wider?

Slot Canyons As a stream flows downslope and gains more water from tributaries, the valley becomes wider because of greater mass wasting.

How does a river change along its course?

Long profiles It often flows over a series of waterfalls and rapids. As a river flows down steep slopes, the water performs vertical erosion . This form of erosion cuts down towards the river bed and carves out steep-sided V-shaped valleys.

How do rivers change as they leave their source and enter their course?

A river changes shape as it flows from its source to its mouth. The shape of both the long profile (a slice through the river from source to mouth) and the cross profile (a slice across the river) changes.

What is downcutting in a stream?

As downcutting occurs, the river channel progressively reaches lower elevation. Downcutting is a form of erosion. The lowest elevation that a river channel can erode is referred to as ultimate base level.

How much does a stream's ability to move sediment change if the stream's velocity is doubled?

For example, doubling the velocity results in a 64 times increase in the competence. Capacity varies as the discharge squared or cubed. So tripling the discharge results in a 9 to 27 times increase in the capacity.

How can a stream change a valley quizlet?

By removing rock and sediment from the stream channel, a stream deepens, widens, and lengthens its own valley.

How did Grand Canyon develop?

Scientists estimate the canyon may have formed 5 to 6 million years ago when the Colorado River began to cut a channel through layers of rock. Humans have inhabited the area in and around the canyon since the last Ice Age. The first Europeans to reach the Grand Canyon were Spanish explorers in the 1540s.

How can a stream change a valley?

Over time, as the stream continues to meander, it erodes away material on the valley floor, ever widening it. The shape of the valley changes progressively from a sharp V to a broader V to one that has a flat floor.

How did the Grand Canyon get so wide?

Much of Grand Canyon's width has been gained through the erosive action of water flowing down into the Colorado River via tributaries. As long as water from snow melt and rain continues to flow in these side drainages, erosion will continue.

Which type of rock forms when less resistant rock yields to mass wasting at rates faster than stream downcutting?

Canyons form where the rate of stream downcutting is faster than the mass wasting of the rock lining the walls of either side of the channel. Valleys form where less resistant rock yields to mass wasting at rates faster than stream downcutting.

Where does water cut away?

The water begins to cut away at the outer arc of where it is moving the fastest. Each curve begins to move sideways and to become more pronounced over time.The stream continues to cut away at the outside of the bank, forming a cut bank. On the inside, sediment settles and a point bar is eventually formed.

How do meanders form?

Meandering streams form where running waters travels over a broad floodplain under lain with soft substrate, in a region where the river has a very gentle gradient. If the stream starts out straight, natural variations in the water's depth causes ...

Concepts of Geomorphic Cycles and Landscape Development

Geomorphic cycle also called a geographic cycle, or cycle of erosion, theory of the evolution of landforms. American Geographer William Morris Davis (1850-1934) was the first geomorphologist who proposed the model of the cycle of erosion.

Davis Model of Cycle of Erosion

Davis postulated his concept of ‘geographical cycle’ popularly known as ‘cycle of erosion’ in 1899 to present a genetic classification and systematic description of landforms. Later through a number of papers and articles modified his work several times.

Normal Cycle of Erosion

The cycle of erosion which is carried by running water is known as normal cycle of erosion. This is because running water or fluvial processes are most widespread all over the world. It plays an important role in the regions of glacial and arid. W. M.

When two streams come together, they form a second stream?

When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream.

What is the point at which a stream emerges from an underground course through unconsolidated sediments or through caves

Spring . The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can, especially with caves, flow aboveground for part of its course, and underground for part of its course.

What is a distributary channel?

A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. Distributaries are a common feature of river deltas. The phenomenon is known as river bifurcation. Distributaries are often found where a stream approaches a lake or an ocean. They can also occur inland, on alluvial fans, or where a tributary stream bifurcates as it nears its confluence with a larger stream. Common terms to name individual river distributaries in English-speaking countries are arm and channel .

How is the gradient of a stream determined?

The base level of erosion is the point at which the stream either enters the ocean, a lake or pond, or enters a stretch in which it has a much lower gradient, and may be specifically applied to any particular stretch of a stream.

What is a stream smaller than a creek?

A stream smaller than a creek, especially one that is fed by a spring or seep. It is usually small and easily forded. A brook is characterised by its shallowness.

What is the fall of water where the stream goes over a sudden drop called?

The fall of water where the stream goes over a sudden drop called a knickpoint; some knickpoints are formed by erosion when water flows over an especially resistant stratum, followed by one less so. The stream expends kinetic energy in "trying" to eliminate the knickpoint.

What is a tributary stream?

A tributary is a contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river (a parent river). Sometimes also called a branch or fork.