What is flow in mass wasting?

Flows are rapidly moving mass-wasting events in which the loose material is typically mixed with abundant water, creating long runouts at the slope base. Flows are commonly separated into debris flow (coarse material) and earthflow (fine material) depending on the type of material involved and the amount of water.

What is the meaning of earth flow?

earthflow, sheet or stream of soil and rock material saturated with water and flowing downslope under the pull of gravity; it represents the intermediate stage between creep and mudflow.

Is water flow mass wasting?

Mass wasting is the movement of rock and soil down slope under the influence of gravity. Rock falls, slumps, and debris flows are all examples of mass wasting. Often lubricated by rainfall or agitated by seismic activity, these events may occur very rapidly and move as a flow.

What is the difference between flows and slides?

Flows are a mixture of water , rock and sediment. They move very quickly . A Slide happens when a section of soil or rock suddenly gives way and moves down a slope . The material moves as a single mass along a slippery zone.

What is earth flow mass?

An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow.

What causes earth flow?

A rapid earth flow typically begins as a small landslide on a steep bank where a stream or river has eroded a valley into a sensitive clay deposit. Excess precipitation, elevated ground-water levels, earthquakes, pile driving and long-term erosion have triggered such earth flows (Sharpe, 1938; Lefebvre, 1996).

Which is the fastest type of flow?

A rock fall are the fastest of all landslide types and occurs when a rock falls through the air until it comes to rest on the ground—not too complicated.

What type of mass movement is flow?

Flows are rapidly moving mass-wasting events in which the loose material is typically mixed with abundant water, creating long runouts at the slope base. Flows are commonly separated into debris flow (coarse material) and earthflow (fine material) depending on the type of material involved and the amount of water.

What classification is mass wasting?

15.2 Classification of Mass Wasting

What is slow mass wasting?

The slowest and least noticeable, but most widespread of the slow mass wasting categories is creep. Creep involves the entire hillside, and is characterized by very slow movement of soil or rock material over a period of several years.

How are sediment flows classified?

The rheology of a sediment gravity flow in its depositional phase is determined by three parameters: (I) the flow is either laminar or turbu- lent; (II) the concentration of the flow is either low or high; (III) the flow behavior is either fluidal (cohesionless) or plastic (cohesive).

What does mudflow mean in science?

mudflow, flow of water that contains large amounts of suspended particles and silt. It has a higher density and viscosity than a streamflow and can deposit only the coarsest part of its load; this causes irreversible sediment entrainment.

How fast is a debris flow?

Debris flows can travel at speeds up to and exceeding 35 mph and can carry large items such as boulders, trees, and cars. If a debris flows enters a steep stream channel, they can travel for several miles, impacting areas unaware of the hazard.

What are flow deposits?

Grain flow deposits are characterized by a coarsening-upward distribution of grain sizes (inverse grading) within the bed. This results from smaller grains within the flow falling down in between larger grains during grain-to-grain collisions, and thereby depositing preferentially at the base of flow.

What is the difference between mudflow and debris flow?

Debris-fan floodplain means a floodplain that is located at the mouth of a mountain valley tributary stream as such stream enters the valley floor. A mud flow is a geologic phenomenon whereby a wet, viscous fluid mass of fine-to-coarse-grained material flows rapidly and turbulently downslope, usually in a drainageway.

What is landslide and debris flow?

In a landslide, masses of rock, earth or debris move down a slope. Debris and mud flows are rivers of rock, earth and other debris saturated with water.

What types of debris flows are there?

There are two types of debris flows, known as Lahar and Jökulhlaup.

Where are debris flows common?

Areas where surface runoff is channeled, such as along road- ways and below culverts, are common sites of debris flows and other landslides. Debris flows commonly begin in swales (depressions) on steep slopes, making areas downslope from swales particularly hazardous.

How does debris flow happen?

A debris flow is a moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence of gravity. To be considered a debris flow, the moving material must be loose and capable of “flow,” and at least 50% of the material must be sand-size particles or larger.

What factors affect debris flows?

Debris flows can be triggered by intense rainfall or snowmelt, by dam-break or glacial outburst floods, or by landsliding that may or may not be associated with intense rain or earthquakes.

What happens in a flow geology?

Flows are a mixture of water, rock and sediment. They move very quickly. Large flows can bury entire villages. Smaller flows can block roads.

What is topple in mass movement?

Topple. This is characterized by the tilting of rock without collapse, or by the forward rotation of rocks about a pivot point. Topples have a rapid rate of movement and failure is generally influenced by the fracture pattern in rock. Material descends by abrupt falling, sliding, bouncing and rolling.

What are 4 types of mass movement?

There are four different types of mass movement:

• Rockfall. Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.
• Mudflow. Saturated soil (soil filled with water) flows down a slope.
• Landslide. Large blocks of rock slide downhill.
• Rotational slip. Saturated soil slumps down a curved surface.