debris flow

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. They are very dangerous and should be avoided at all costs.
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1. The rapid, downward mass movement of particles coarser than sand, often including boulders one meter or more in diameter, at a rate ranging from 2 to 40 kilometers per hour. Debris flows occur along fairly steep slopes. 2. The material that descends in such a flow.