Question about crossing a river...

[MtB]

When crossing a river...
Some rivers are slow and others are a raging torrent, and some can be both. Somewhere in there, there is a safe, unsafe, and dangerous speed. When gauging a river's speed in miles per hour, does anyone know at what speed it would be deemed unsafe then dangerous to cross? We aren't counting in random factors like short heavy people and tall light ones and pack weights that would skew what would be deemed safe and unsafe. I'm looking for a generality.

Let's say you are crossing a river at knee to mid-thigh depth, and the river bed is stony/rocky, but otherwise clear of debris. You've got your pole, you're facing upstream, and your pack is slung over one shoulder. The river, you estimate is about 2.27mph...

So, would, for example, a river speed of 2.27mph be safe, a river speed of 5mph be unsafe, speed of 7mph be dangerous?


If you're interested, I calculated the speed of the river by:
1. Measuring out a 100ft straight length then tossed in a stick and timed how long it took for the stick to travel the 100ft.

2. I then divided 60 by that time and then multiplied the result by 100 in order to dertermine the distance travelled in 1 minute.

3. This result was then multiplied by 60 to find the feet distance travelled in 1 hour.

4. That result was then divided by 5280 (5280 feet per mile) as best I could to determine the rough miles per hour.



Thanks to any and all respondents.

[Silverback]

Welcome to the forum.

Water is powerful, relentless yet predictable in normal circumstances. Flood water and rivers in spate cause additional risk factors.

Conditions such as the banksides, bed obstructions, floating debris all add risk, and too many variants to say that one speed of water is safer or more dangerous than another although it is widely accepted that the faster the flow the less depth required to sweep you away.

Wading in water over your knees increases the dangers of being swept away. There are many good resources on the web. YouTube has some examples of how dangerous water can be.

[jus_young]

I look at it, question myself, and then probably go another way. In all seriousness its just not worth the risk unless its really slow moving. I even took a look at a ford this evening as I was driving to a call out that I had to cross to get to the job. I didn't take the ford, I turned around and found another way as it just did not seem worth the risk with the flows being the way they are at the moment.

[Silverback]

it just did not seem worth the risk

T^

[treefrog]

In Russia, river crosses you....



http://www.youtube.com/watch?feature=player_detailpage&v=w1-Dh5rrVCU

[paulthefish2009]

Welcome to the forum mate,my advice would be don't..............................ever! Paul

[David_JAFO]

hello,
:welcome: 2 the forum.
Regards
David
T^

Welcome to the forum mate,my advice would be don't..............................ever! Paul

[Bob W]

I do a lot of wading in rivers whilst fishing.

There's a lot of variables to take into consideration, but I'd say if there's one iota of doubt in your mind about going in, don't!

Generally, if you can see the bottom it's normally shallow enough to walk into, use a stick to probe the bottom in front of you and keep an eye upstream for any objects, fallen branches, dead cows :mad2: etc coming down that could hit you. If you start to feel out of your depth or not too sure in any way, turn back and look for somewhere else to cross.

I rarely go all the way across, usually wearing chest waders I get out to where I can run a float comfortably down a crease or present a bait where I couldn't from the bank.

Personally, I'd consult an O/S map and walk up or down stream to the nearest bridge if I couldn't a place to cross that I was 100% confident in.

[Silverback]

I do a lot of wading in rivers whilst fishing.

There's a lot of variables to take into consideration, but I'd say if there's one iota of doubt in your mind about going in, don't!

Generally, if you can see the bottom it's normally shallow enough to walk into, use a stick to probe the bottom in front of you and keep an eye upstream for any objects, fallen branches, dead cows :mad2: etc coming down that could hit you. If you start to feel out of your depth or not too sure in any way, turn back and look for somewhere else to cross.

I rarely go all the way across, usually wearing chest waders I get out to where I can run a float comfortably down a crease or present a bait where I couldn't from the bank.

Personally, I'd consult an O/S map and walk up or down stream to the nearest bridge if I couldn't a place to cross that I was 100% confident in.

Sound Advice. Worth remembering that debris floats in rivers at 3 levels so you may not see what takes your legs away.

If you do go in and you find yourself being swept down stream try to float in the defensive swimming position which is on your back feet downstream, only turn onto your front head first down stream to eddy break into a place of safety or to swim over a strainer.

Putting your feet down in water you cant comfortably wade in is a potential recipe for disaster - the risk of foot entrapment is high.

Have a look at this - these are trained water rescuers !! This was a body recovery by the way. In the part where the guy stands up it isn't that deep, tying a rope around you is so dangerous and tyres don't float


http://www.youtube.com/watch?v=tnPQIr8dl5A

[Ehecatl]

Long, long ago, in a place far, far away I was fortunate enough to get a place on a Mountain Leadership Training Board course (so I'd be safer taking cadets out onto the hills). In addition to plenty of navigation and yomping, we did some basic safety on steep ground (rope work) and river crossing.

The instructor was clear that the techniques (both rope work and river crossing) were for those very, very rare situations that you should not have got yourself into in the first place.

M@

[Silverback]

Particularly relevant for this time of year sudden immersion in very cold water is going to reduce your swimming ability to near zero (rapid swim failure), unless of course you regularly acclimatise (proven medical fact).

If you cant swim effectively then you will use up oxygen & energy in wasted swimming attempts, couple this with the fact that moving water strips body heat 100 times faster than still water - which is 25 times faster than into air you have the potential to get into real difficulties.

http://jap.physiology.org/content/100/6/2057.full

http://beyondcoldwaterbootcamp.com/en/4-phases-of-cold-water-immersion

[SimonB]

Particularly relevant for this time of year sudden immersion in very cold water is going to reduce your swimming ability to near zero (rapid swim failure), unless of course you regularly acclimatise (proven medical fact).

If you cant swim effectively then you will use up oxygen & energy in wasted swimming attempts, couple this with the fact that moving water strips body heat 100 times faster than still water - which is 25 times faster than into air you have the potential to get into real difficulties.

http://jap.physiology.org/content/100/6/2057.full

http://beyondcoldwaterbootcamp.com/en/4-phases-of-cold-water-immersion

The potential for a heart attack aswell....... Caused by the massive shock from the submergence.... Drowning by inhalating water.. One of the most natural occurences to happen when you go into sudden shock.. Also known as taking your breath away.....

Avoid a river crossing, and do so only as a last resort.. Don't be a Bear Grylls.... He has backup when he does it.. You won't.

[Silverback]

Also known as taking your breath away.....


The mammalian diving reflex.

And if you do manage to swim to safety then hypothermia is a very real possibility unless you start to get warm, quickly. Just because you put on dry clothes it doesn't mean you will warm up sufficiently, theres this thing called after drop where your core temp continues to drop faster than you can generate heat.

Theres also the possibility of post rescue collapse caused by the removal of the hydrostatic pressure which kept your blood pressure higher than when out of the water(yes even in rivers), as you emerge you could lose consciousness and fall back in, or fall to the ground occlude your airway and die....not looking promising so far is it ?

Even if none of these things happen then theres always the possibility of secondary drowning

Secondary drowning can be difficult to recognise, since the victim initially appears to be OK after a near-drowning incident. In some cases, however, enough water has entered the lungs to cause a drop in blood oxygen levels, and death may occur between one and 48 hours later.

Drowning does not necessarily have to involve ingestion or aspiration of large amounts of water or other fluids. During cases of secondary drowning, very little fluid is actually present in the victim's lungs. This small amount of liquid is still enough to make the lungs no longer able adequately perfuse the body tissues so the victim eventually succumbs to the lack of oxygenated blood. Death is generally attributed to a pulmonary oedema, similar to the effects of acute pneumonia or wet drowning.

Secondary drowning is difficult to detect due to the slow acting nature of the condition. A victim may believe they have successfully expelled it through coughing.The heart does not slow down appreciably during this process, so the victim can still walk and talk. The only symptoms may be a sudden change in personality or level of awareness as the blood oxygen level drops over time.

This condition can be confused with dry drowning, in which a laryngospasm causes suffocation.

[paulthefish2009]

Well I think the above posts just back up what I said earlier...........don't............ever! Nice answers everybody. Paul