Training Guide Swiftwater Rescue

• Upstream V created by water hitting an object and then going around it. 
• Downstream V created by water flows convergence at a point of least resistance

Upstream V's should be noted as they indicate areas that may be trapping a subject against an obstacle. The Upstream V as shown in figure- 2 helps to indicate where the obstacle lies. Visible eddys downstream of an obstacle can be possible resting spots or dead zones that may be passively holding a subject from further travel down the waterway. 

Downstream V's are generated by water moving around several obstacles coming together in the path of least resistance. These downstream V's will contain some of the fastest moving water in the channel. If the subject does not become trapped, the downstream V's have the highest probability of containing the subject.  

Holes and Pillows are also indicators of a submerged or partially submerged obstacle. The pillow will lie upstream if the obstacle is completely below the surface of the water and downstream if the obstacle extends above the surface of the water. A hole is created by the void formed by water swirling around the obstacle. Water flows back into the hole to fill the void which may cause a strong flow of upstream current immediately following the obstacle.  

Local hazards play a large role in local waterway rescues. Holes as explained above can create a strong upstream current. Striking these upstream currents while traveling downstream may be equivalent to striking a solid surface. An extended head or neck could be easily injured if submitted to this abrupt change in water-flow direction.  

Potholes or Drains are areas where water is dropping or flowing through an opening in the waterway bottom. This is often the case when the waterway is created by large boulders. The result is similar to outside water flowing through the drain of a bath tub. Once trapped, only a strong mechanical advantage system will be able to pull the subject free from the drain's grasp: Assuming it is possible to attach the haul system to the subject.  

Undercuts are similar to drains except the flow is still mainly horizontal with the obstacle thickness being smaller as the water runs deeper. This area may jam and contain a submerged subject as he passes the obstacle. As is different than the drain, the undercut may eventually rip the subject free. Debris, logs, and swimmers (even those with PFD's) can easily be pulled and held in an undercut. Undercuts can best be searched by polling with the shephard's crook in a fashion similar to avalanche searches. There is virtually no practical rescue technique from undercut entrapment.  

A Sluice is a narrow section of the waterway. If the passage is too small to pass a person, this may be another site of a submerged trapping. When water is well above the sluice, the typical waterflow will carry the subject above these narrow parts. The shepherd's crook may be used to lift the subject, or to place a rope around a subject trapped in a sluice. If trapped with head upstream, waterflow may actually be forced into the subject completely filling lungs and rendering all subsequent recovery unsuccessful.  

Standing Waves: Caused by water increasing in speed as it drops over or through a gentle slopping areas, then the water piles up against slower moving water. Usually found in chutes or after downstream V's

Strainers are devices that operate as a colander does with spaghetti. Tree limbs, exposed roots, submerged cars all may allow water to flow but may trap a person as he passes.

Limb Entrapment is probably the most common hazard, where an arm or a leg becomes wedged into a rock or submerged debris and the body is held downstream by the force of the water. This is depicted in figure- 3. For this reason if one finds himself trapped in a channel he should travel feet first with his feet high as is shown below.

Backstroke swimming should be used to navigate around the channel. The position should be changed to a head first freestyle position when it becomes necessary to vault or pass over obstacles. One should never stand in moving water deeper than knee deep without additional support. If a person falls prey to limb entrapment, the primary rescue must be to support the subject by some means to keep his airway open (sounds familiar). Subsequent rescue will be to place a rope or prying instrument into position to remove the trapped limb.  

• Hydraulics form when water flowing over the top of the obstruction hits the water below creating a hole or depression which is filled in by the downstream water or backwash.
• Hydraulics are created both by natural and manmade objects.
• Natural hydraulics such as rocks, have an escape because of the non uniform surface and the flow of water
• Manmade hydraulics, such as low head dams, are to perfect and have a uniform flow from end to end with little chance of escape.
• The design of a low head dam will have a direct effect on the intensity of the hydraulic

Low Head Dams are river obstacles that create a deadly trap for exposed subjects in the waterway. If the low head dam is sufficiently covered with water flow, a continuous "Hole" that extends across the waterway may be generated. If the subject makes it to the top surface he will be trapped between the Boil line and the dam by the flow of the intense backwash.  If a subject is trapped in the recirculating water below the surface, he will quickly loose orientation and expire unless he can escape the motion. A possible escape route is shown below. A subject trapped in such a situation is in most critical need of outside action. A raft rescue or a helicopter static fly away is often the only reasonable chance the subject may have for survival.  

Another major hazard or obstacle in water rescues in the urban setting are the sloped smooth walls of the commercial concrete drainage. This sloped effect helps reduce stagnant water during low flow and also prevents an accumulation of debris. This slope however adds difficulty to the basic reaching rescue. Anyone operating near this type of channel must be secured with at minimum a belay line with a quick eject harness. The more systems work that is required the less mobility and flexibility the rescue team has to effect a rescue at a particular site. However the lack of debris and the uniformity of the channel will allow the subject to proceed with relative safety if he is not panicking or already injured or unconscious.