Crossing rivers

 

River crossings are potentially dangerous. The impacts of delays from waiting for waters to subside, or taking circuitous routes to avoid a crossing or to find an easier one put enormous pressures on leaders. You need a good understanding of the forces of moving water, and to have the technical skills to manage difficult crossings. Further, most groups do not carry the necessary equipment for a difficult crossing or a rescue if something does go wrong. This chapter is about river crossings - how and when, and the issues involved in the decision to cross or seek alternatives.

Anyone who has been caught by rising floodwaters knows only too well the frustration that they cause and the decisions that need to be made. Many things influence these decisions. They may include the warm bed and the hot food that is waiting on the other side of the river or it may be that you or one of your party has a deadline to meet. Whatever the factors, never let them override the most important issue of all— the safety of you and your group.

Some river crossings are straightforward and require very little planning. Many river crossings can be dangerous. Deaths have occurred in bushwalking groups crossing rivers in Australia. Walks and skitours should be planned so that difficult or frequent river crossings are avoided.

Planning for a river crossing

As a leader you have an obligation to ensure your party is not injured as a result of a decision you do or do not make. This should be ever present in your mind when making decisions that involve river crossings.

Before leaving for your trip you should find out all you can about the area you intend to visit. If a river crossing is necessary then it is important that the group knows this, and consideration is given to any specialised equipment required to minimise risk. Enquiries should include the swimming ability of individual members in the group, the likely river levels in the area you intend to walk or ski, any change to that level due to weather, irrigation or hydro electric requirements, and any suggested or possible crossing locations and escape routes if the crossing is doubtful. If this information is gathered before you go it will help you assess the group and the conditions as you travel.

Once you decide that a river crossing is necessary and your group is capable of completing it safely, you should continually assess the group’s progress during the walk. Factors that could influence the decision to cross or not to cross may include the mental state of the group, the physical state of individuals within the group and the time you reach the intended crossing. It may be better to wait until the next day before the crossing is attempted. Crossings should not be attempted in the dark.

When assessing a potential site the following should be considered:

  • depth
  • speed—water velocity is usually the most obvious danger, and even ankle deep water can move fast enough to knock a person off their feet
  • channel bottom—this can be hazardous, such as slippery surfaces, very smooth surfaces, or an uneven boulder strewn bottom
  • number of walkers—being able to utilise methods involving a number of persons gives more options than if there is only one person.

Any factor which obscures the view of the bottom poses an additional hazard. This includes suspended material such as mud or silt, and floating matter such as algae or plant material.

Assessing a river

No two rivers are the same and all are subject to constant change due to differing flow rates, so it is important that a leader has the skill and knowledge to distinguish between safe and dangerous places to cross. Before this is achieved, a leader must have a basic understanding of what occurs to water when it is forced over, through and around different obstacles. River reading is an art which cannot be learned from books alone, but the factors below are a good start in knowing what to look for.

Current
Current is the most basic feature of a river. In a perfectly symmetrical river the current will be strongest in the deeper centre section. The strongest current will sweep around the outside of a river bend. When constricted, water is forced through the narrow point, gaining speed, and then slows again where the river broadens. As the river gradient steepens (the rate of fall downhill of the riverbed) the current will be swifter. Where there is a constriction combined with a drop, the section is known as a shoot.

Stopper-waves
A stopper wave occurs where a very strong current of water flows over an obstruction, creating a wave or current below the obstruction which appears to flow back upstream. Naturally occurring stopper-waves caused by boulders, logs or other debris are dangerous because objects (including people) can be trapped in the stopper, and escaping from it is difficult. Escape might be possible by swimming to one side of the stopper, or, for larger stoppers, diving deep and swimming downstream.

Strainers
Strainers are extremely dangerous. They are fixed objects that allow the current to pass through them, such as a fallen tree with many branches in the water. They are often the most dangerous hazards that have to be dealt with. The danger is that while water can move through and around, solid objects are pinned against the strainer on the upstream side.

Eddies
Eddies are sections of river which swirl around, and can result in people or objects being trapped in the whirlpool, and unable to get to shore or into the main stream flow.

Assessing a site for crossing

Once the decision has been made to cross, a suitable area should be chosen. Test the depth and the type of riverbed. Choose an area where the current is slowest. Remember it may be easier to wade across a pool that is 1.2 m deep than cross a narrow shoot that is 50 cm deep with fast-moving water. Choose an area with a suitable entry and exit point. Carefully consider what mishaps could occur during the crossing, and assess what action you could take in response. Where would a swept person end up? If possible, position a party member at this location to act as a safety person. Make sure there are no immediate dangers downstream.

Clothing and equipment

If you do go for a swim it is going to be important that your spare clothes are dry and warm at the end of the ordeal. All personal items such as spectacles should be fastened or removed if possible. All items in your pack should be in waterproof containers/ bags. Putting the sleeping mat at the top of your pack helps buoyancy. Always wear close-fitting garments to ensure you do not become snagged on an obstacle. It is important that boots are worn to limit any possibility of ankle and foot injuries.

River crossing methods

For all river crossings, keep your pack hip-belt done up if it is a quick-release type. Sternum straps should be undone, and shoulder straps loosened. This transforms your pack into an attached personal flotation device in the event that you do end up swimming.

Individual without aid
It is possible to cross by yourself if the current is not too fast nor the water too deep. Knee height is usually the limit. This should only be attempted in the most basic of crossings. It involves choosing a clear route at 45° to the current. Move into the current and walk across and downstream, with the side of your body to the current. This prevents the legs buckling at the knee joint. Small steps and sure foot placements are required for this method.

Individual with a pole
If stability is required a pole may be used. The pole should be 2–2.5 m long and 6–8 cm in diameter. This method is suitable for rivers that are not swift flowing and are not deeper than the waist. It requires the riverbed to be relatively flat and snag free. The route taken is directly across the stream at 90° to the bank. Position the pole so it is upstream of your body, press it against the bottom and when secure walk forward leaning on the pole. It could be said that the base of the pole on the riverbed is being used as a pivot point for the person scribing an arc.

Group mutual support
This method is highly recommended for groups of two to 12 or more people. It provides a semi-rigid structure that is flexible enough to maintain position in the current while being loose enough to correct any mistakes that may occur during the crossing. Each individual is held twice at each join, providing excellent back up should one person let go.

The group stands in a line parallel to the river bank and the current. Everyone leaves their pack on and the hip-belt done up, unless the hip-belt is not quick release, in which case it should be undone. Shoulder straps should be loosened and sternum straps undone.

Each person puts their arms behind the next person’s back, between the pack and the back. They then grasp the base of the shoulder strap on the opposite side, or the hip-belt in the same position. If no packs are used, the arms go behind the backs and grasp clothing at waist level.

Connected closely in this way, the whole group crosses the river together. Should the group need to retreat from the river without completing the crossing, the whole group should walk backwards all the way into safe, knee-deep water.

Triangle of support
As shown in Figure 30.1, three people face inwards with arms firmly linked, heads close together, and feet apart. The heaviest person faces upstream, with the other two sideways to the current. Only one person moves through the water at a time. In this way, the two who are stationary support the one who is moving, but with the greatest care.


Line astern
Three or more people stand, one behind each other, facing into the current, and give each other support by holding onto each other’s belt. The front person moves first, then number two who should be the heaviest, and finally the third, until the party is in one line again. In fast-moving water, each member of the group moves at the same time.

Line abreast using a pole
Three or more persons stand in a line, parallel to the river bank with arms interlocked and holding onto a long pole. Everyone moves together, giving each other support, with the strongest person on the upstream end.

Crossing with a rope
Roped crossings are generally not recommended for bushwalkers and ski tourers. Roped crossings require a great deal of skill and equipment, and should only be attempted by people who have formal training or experience in rope work and swift water rescue. There are several types of roped crossings, but as most walking parties do not carry the required amount of equipment to effectively set up a safe, roped river crossing, they are often impossible in practice. Specialist courses can be taken to improve skills in these areas.

No matter which method is used, there are certain rules and precautions that should be observed. These include:

  • multiple points of contact with the bottom
  • move one point of contact at a time
  • swim if you fall—do not put your feet back down until you have safely reached calm shallow water

Self-rescue and survival techniques

It is crucial that the leader has the skills associated with river crossings to allow them to facilitate a safe and successful crossing for the entire party. Even when all procedures are followed however, accidents do occur. The leader and the group need an understanding of the safety procedures and principles that must be adopted whenever a person finds themselves in water more than neck deep.

If you lose your footing while attempting a river crossing your best chance of rescue is saving yourself. The following approaches are recommended:

  • Assume the white-water safety position—on your back, position your feet downstream, and feet up with your toes out of the water to avoid foot entrapment.
  • Watch for obstacles.
  • Place your thumbs in the lower part of your pack straps and push down. This should keep your shoulders up in the top of the straps and your head above water.
  • Keep your heels slightly lower than your buttocks.
  • As your feet contact rocks, either flatten out to slide over shallow rocks, or use your feet to fend them off, then use your hands to turn around and point your feet down river.
  • You may be able to move from one side of the current to the other while in this position. This is known as ferry gliding and requires the swimmer to move the body from side-to-side using the hands. If done correctly a swimmer can change the angle of the body so the force of the current strikes one side in particular. This will move the swimmer towards the river edge.
  • Don't panic, but try to assess the situation and seek the best alternative.
  • Don't try to stand up.
  • Stay in the main stream until an eddy can be reached. When it is possible to swim, backstroke or side stroke to catch the eddy, quickly get out of the water and make yourself visible.

Foot and body entrapment

If you attempt to stand in moving water your feet may become trapped in rocks. If this occurs the water pressure can build up on your legs and body until you are forced into a horizontal position on the bottom of the river. Many people have drowned as a result of foot entrapment, so do not try to stand in water any deeper than your knees.

River crossing in snow covered areas

When crossing rivers and streams in snow-covered areas, leaders should be very aware of cold and exposure injuries. Remember that the water being crossed will be extremely cold, and if people spend an extended time in the water, they will soon lose all feeling and ability to use those limbs in the water.

Whenever possible avoid crossing rivers in such cold environments. When planning your trip, you may want to consider packing a pair of wet-suit boots to protect your feet and keep your boots dry.

Crossing snow bridges is a particular danger nearly all skitourers face at times. Assessing the strength of a snow bridge is difficult, and the consequences should a person end in the water (or in a crevasse) are potentially very serious indeed. Examine any snow bridge you are considering crossing carefully from the side. Consider the thickness of the bridge, and in particular the amount of ice within the layers of snow, and at the bottom, as it is the icy layers which give strength. Also consider the temperature, and the part of the snow season. Bridges which are very cold are stronger, and those warming toward the end of the snow season will be much weaker. Be very wary of snow bridges even when they appear secure. Think what would happen if the snow bridge gave way. How deep is the water? Can you get out, or is there a steep, high wall? Most importantly, can you get access to the river if someone else fell in? All of these considerations need to be taken into account. As a general principle, if in doubt, find another way!

If the decision is taken to cross a snow bridge, there are a number of generally accepted principles:

  • Try to cross smoothly and quickly, with even weight on both skis.
  • Do not kick down hard if diagonal striding – the downward pressure could crack the bridge.
  • If the bridge is level with the stream bank, approach and leave the bridge at 90o
  • If the bridge is much lower than the surrounding area, this is a danger sign. If you have to cross such a bridge, approach it from the lowest level possible, generally from one side, and cross it by making a U turn from one bank, across the side of the bridge, and onto the other bank.
  • Do not approach a lower level bridge at 90o, as your downward momentum is likely to crack the bridge.
  • Send the lightest and most agile skier first.
  • Send the least experienced skiers across in the middle of the group, as the bridge is likely to become weaker with each person crossing, and having the least capable skiers separated from the main group by a broken snow bridge is a very serious situation.
  • If the bridge cracks and breaks under a person, they must throw themselves forward – the snow behind them will already be broken.

The issue of crossing on skis or on foot is a complex one, but crossing on skis is generally preferred, as it is quicker, smoother and results in less jarring onto the bridge. However, if a person does go though a snow bridge, extricating themselves from the water is much easier without skis. For this reason, undo safety bindings to make the job of releasing skis easier should this be necessary.

River crossings are one of the most dangerous hazards encountered when bushwalking or ski touring. Leaders must be attentive and diligent at all times when tackling river crossings. If in doubt do not cross!

References

Goldring R. 2000 Personal communication.

Skiers in a dangerous location