What is the difference between mudflows and debris flows?
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 does a debris flow look like?
Definition: A Debris Flow is basically a fast-moving landslide made up of liquefied, unconsolidated, and saturated mass that resembles flowing concrete. In this respect, they are not dissimilar from avalanches, where unconsolidated ice and snow cascades down the surface of a mountain, carrying trees and rocks with it.
What causes hyperconcentrated flow?
Hyperconcentrated flows, as described by Pierson (2005), lies on the continuum between floods and debris flows. A flood transitions into a hyperconcentrated flow when particles on the bed begin to move together, en masse, and coarse sediment becomes suspended in the flow.
Is debris flow a slurry flow?
Debris flows are channelized slurry flows consisting of sediment-water mixtures incorporating fine material (sand, silt and clay), coarse material (gravel and boulders) and a variable quantity of water.
What is a rockslide in geography?
A rock slide is a type of landslide occurring when a mass of rock moves quickly downslope. Rock slides happen in mountainous regions or where artificial excavation is taking place (e.g., mines and quarries).
What precedes a debris flow?
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 is rockslide landslide?
A rockslide is a type of landslide caused by rock failure in which part of the bedding plane of failure passes through compacted rock and material collapses en masse and not in individual blocks. Note that a rockslide is similar to an avalanche because they are both slides of debris that can bury a piece of land.
Is debris flow a type of landslide?
Areas recently burned by a forest fire are especially susceptible to debris flows, including the areas downslope and outside of the burned area. Debris flows are a type of landslide and are sometimes referred to as mudslides, mudflows, lahars, or debris avalanche.
What is the difference between sediment and debris?
Debris flows have volumetric sediment concentrations exceeding about 40 to 50%, and the remainder of a flow’s volume consists of water. By definition, “debris” includes sediment grains with diverse shapes and sizes, commonly ranging from microscopic clay particles to great boulders.
What is a debris flow pathway?
Debris Flow Pathways delineates areas likely to be in the path of these slope movements. if they do occur. The pathways include areas significantly further downslope from where. the slope movements may initiate. Designated units on this map are known debris flow.
What is a typical concentration of sediment in a Hyperconcentrated flow?
Hyperconcentrated flows may contain anywhere from 5–60 % sediment by volume. Higher concentrations tend to be characteristic of debris flows, less of normal fluvial flow.
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.