Debris flow
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Debris flows are often referred to as mudslides, mudflows, jökulhlaups, or debris avalanches. There is also a debris flow type that has rocky front called 'the head' and a 'tail, like wet concrete. This debris flow has been well reported in the scientific literature. They consist primarily of geological material mixed with water. The composition of this type of flow is mainly soil and other matter, such as trees and rock fragments, that are picked up as the flow moves down a slope or channel. Debris flows may be generated when hillside colluvium or landslide material becomes rapidly saturated with water and flows into a channel. Heavy rainfall, snowmelt, or high levels of ground water flowing through cracked bedrock may trigger a movement of this type. Debris flows and floods may also occur when strong rains on hill or mountain slopes cause extensive erosion and/or what is known as "channel scour". Debris flows can be as thick as wet mud mixed with rock, and can transport very large boulders. Debris flows may also eventually become thinner muddy flood waters as they deposit their heavier components. Geological debris flows tend to move in pulses as friction or other barriers are overcome during the flow. Sometimes earlier pulses or previous debris flows form levees that channel the flow until they are breached. The presence of older levees indicates the recurrence and characteristics of debris flows in a particular area. This can be important information for developing land on what are known as alluvial fans.
Theories and models of debris flows
Debris flows as mud flows
- Rheologically based models that apply to mud flows that are treated as a homogeneous liquid (Examples include: Bingham, visco-plastic etc
- The mixture theory of Iverson
- Dam break wave eg Hunt
- Roll wave Takahashi, Davies
Unsaturated 'rocky' or 'stony' debris flows
- Progressive wave-Hungr
- A type of translating rock dam-Coleman
