Where do water particles go ?

[Guest]

A few years back I was anchored near Gillingham marina in the Thames Estuary.

I was in the the cockpit filling the water pipe with a water container that fell overboard half full without the cap on.It sailed away with the tide. Still anchored in the same place about 24 hours later what do you think I saw ? . Yes my water container which I collected and still use to this day. Spring tides at the fastest move about 2 knots.

My question to the panel is how do water particles or pollution for that matter, actually move away from a given area ? Also, a bit grim, but how accurate can the police be if the time of death is known for fished out bodies ?

 

[tcm]

Hi vic.

I think you mean that you filing the container, not the pipe. But anyway, the container was a bit filled up, so the opening was weighted to stay above the water level. It floated up on the tide, and then back down on the ebb, perhaps twice, to meet you 24 hours later. Alternatively, if it';s a very common yet awkward water container that isn't easy to control, like an ASDA half-gallon milk ontainer, praps there are several dozen bobbing around in the medway and you've picked up another?

Dead-body-wise, you will need to wrap the body with quite a lot of chain to make it sink. After only a few days, ageing of bodies is down to finding their last use of credit cards, last sighting, or expiry date of milk/water containers attached around their neck in a vain attempt to weigh them down

 

[chippie]

Re: Dead Bodies

Thanks TCM, I always appreciate it when you share your experience with us;-]

 

[vyv_cox]

This seems to be a very complex science. Factors involved often catch out the experts, who of course recommend further study at enormous cost. Witness the sewage outfalls at Llandudno. There are some on the east side of the Orme, a large bay where the sea is relatively current free. There are some on the west side at Deganwy, where the Conwy river ebbs and floods at a rate that must be seen to be believed. Sewage released into the west side outfalls regularly returns and pollution here has been a problem since time immemorial. Effluent that goes out via the east side is gone, never to return. Studies have been carried out using dye, radioactive tracers, artificial poo and even more sophisticated techniques. Still nobody seems to know the answer, except to close the Deganwy outfalls and make more on the east side.

 

[Guest]

Tideology

Have I just made up a new word Vyv ?

Seriously, I think you are right by saying that the whole subject is very complex.

As an aside, a few years ago, Radio 4 had a week long feature on oceanography with many interesting contributors each evening. One thing that scientists are doing is trying to understand the world's currents. They use a 'football' type marker that they place in the worlds oceans that can be pressureised ( lives about 20 metres below the surface) and pops up to the surface every few days and lets them know it's position, salinity etc. They stay in the water for months on end.

They admit that we know very little about the world's currents as this 'football' turns up in the most weird places. In other words, the world's current charts must be taken with a very pig pinch of salt.

 

[Bergman]

I live on the banks of a large tidal river (in a house!) and bodies do occasionally float past. Seen 2 in the last 3or 4 years. The last one was being hotly pursued by 2 policemen -on foot.

No one had told them that the spring flood tide can reach 8 knots.

They had left their car about 3 miles down stream and were nearing exhaustion as they passed our house and the deceased was opening out a clear lead.

The body was eventually recovered about 9 miles upstream.

Clearly the police had no idea of calculating where to look, they knew who the deceased was and where and when he went in.

Tide here certainly not a zero sum thing, flood runs for a bit over 3 hours ebb for about 9. Speed of flow varies enormously with volume of water running off.