Hi,
Just returned from driving Madrid to Ayamonte and back. I noticed along the curving banks of the Guadalquivir river (flowing between Jaen/Cordoba/Sevilla provinces) silver leafed trees. Eucalyptus? You always knew where the river was by these trees.
In Huelva province, the river Odiel burst its banks, flooding fields and houses. The Guadiana, as far as I am aware, has not burst its banks (perhaps upstream in Extremadura?) However, it seems to have a counter current (not sure of the wording) where it appears to flow upstream near the mouth of the estuary/ocean. Any info?
Thanks.

Tidal flow?

Deffo tidal. The river near Ayamonte is salt water and is so for quite a way up (beyond CE I think). Not sure where saltwater turns into freshwater though???

Thanks to both for your replies. That'll be it. I was expecting to see some flooding of the Guadiana between the parador hill and the CE fishfarm, but things appeared to be the same.
Regards,
Carol

The brackish point is generally defined by things like narrowness of the estuary, height of tides, (i know thats less of an issues in that area) force of the river water, aquifiers, and even human impact. Would imagine if the rivers are swollen then the brackish point will be fairly low.

Hi All,

The Guardiana is a very big and important river in the European scale of things that has been reduced to a shadow of its former self by the introduction of many large dams upstream in both Portugal and Spain . Initially I guess to regulate flow from winter snow melt then for water conservation for irrigation and drinking water.

This means that the flow levels now are not what they were and I expect that the tidal flow and brackish water extends further upstream, you can definitely see tidal effects at Alcutim but I dont know if it brackish that far up.

To see the effect of the incoming tide on this part of the coast go to Tavira and stand on the centre of the Roman bridge. When the tide is coming in the river divides neatly in two with the western half flowing upstream and the eastern half flowing downstream.

Regards,

John

Hola! John,
Spent a brief time in Tavira - getting lost looking for Pingo! - and nearly went walkabut across same bridge. But, it was raining! Next time...
Has the Guadiana ever burst its banks at Sanlucar?
Regards,
Carol

Hola Carol,

What is "Pingo"? Tavira is well worth a second visit. As a a civil engineer I would find it hard to say the Guadiana could burst its banks at Sanlucar since the land rises very steeply on each bank to the Castles on top of each hill. The Spanish look down on the Portuguese.

Before the dams were built upstream to conserve water and regulate the flows it may have inundated the lower areas but in those days they were very sensible and would not have built below the memory line. The land below was probably very fertile and would be intensively farmed as it is now just below Sanlucar/Alcutim.

No if the Guadiana has burst its banks in the past it would have been at Costa Esuri where the Marisma is now and also in the area where Golf I now is. The ideal conditions would have been a very high spring tide an onshore gale and winter flood water coming downstream.

It could happen again!

Regards,

John.

Hi John,
In answer to your question, it's either pingo doce or pingu doce (but not the penguin) - a supermarket.
Regards,
Carol

Hi Carol,

Can't help sorry we always pop into Lidel at Tavira for bits and pieces. Right next to the railway station which is well signed. The statues out front of the station are great.

Regards,

John.

Are you sure that the river is dividing in two ?? Could it be that there is an eddy caused by, say the shape of the river or the underlying bed that is causing a counterflow ?? Here in the UK there are all sorts of strange phenomenon with rivers and tides. In the Solent they have a double high tide, where they have a HW , which then ebbs for an hour I believe, returns for another HW, then carries on to ebb for the whole of the ebb tide.
I sail in the Thames Estuary and learning where the eddies lie is a great help.
Sailing into the Medway past the Isle of Sheppey where the ferry port is, if the tide is pouring out against you as you try to enter, sailing close in to shore, as far as you dare, there is a counterflow that will help sweep you in. The only river in Europe I know of that only flows in one direction is the Rhine, but my knowledge is in no way definitive. Similarly I believe the Straits of Gibraltar flow in one direction, eastward, to replace the water lost in the Med by evaporation.

You may be right it could be eddy flow but to stand on the bridge as the tide comes in and the water level rises it definitly seems to be that the east half is flowing in and the western half is flowing out.

I suppose the only way to be definative would be to test the salinity of each half.

If you could get a tidal flow atlas of the region, need to be a good chandlers or chart suppliers, they would show the direction of the flow at various states of the tide. I will post on one of my sailing websites and see what response I get.