Rapids - Forms
Various factors take part in the formation of rapids. Generally, rapids are caused naturally by the interaction of flow rate, constriction, obstruction, and gradient. However, there are also forms of rapids that are influenced, deliberately or not, by man.
Man-made rapids are potentially dangerous because of the presence of obstacles such as sharp rocks. These obstacles should be avoided when possible for these can put the rafters at risk. Also potentially dangerous are big water form of rapids, which are comparable to flood conditions. Big waters can cause tough hydraulics and powerful flows.
In this section, we will focus at the four forms of rapids namely compression, confluence, pool-and-drop, and staircase:
- Compression
In big rivers, the volume of water is sometimes compressed by river bends or canyon walls. Consequently, waves are created by inside bends, and water boils up from underneath, creating circular shapes. This form of rapid consists of hazards such as holes or hydraulics.
- Confluence
The point where two or more rivers meet, a confluence is characterized by eddy fences and whirlpools. Visibility may be low, due in part of the thick vegetation that typically surrounds it.
- Pool-and-drop
Known rapid-runs generally take the form of pool-and-drop. Characterized by alternating short rapids and slow-moving water, pool-and-drops allow rafters to rest whenever possible.
- Staircase
In mountain creeks, routes suitable for Rafting usually have equal width and depth. In these routes, water pours over continuously, resembling a staircase. Here, the ledges usually range from several inches to a few feet high. Banks of rivers that have this rapid form may be sharp.
The four forms mentioned above are just some of the rapid forms known to man. Rapids are continuously being fashioned by the interplay of natural factors and the interference of man. Needless to say, rafters should know the different forms of rapids to get an informed understanding about their adventure arena.
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