Cyprus-Forum.com

by **Sotos** » Tue Dec 12, 2006 1:26 am

This year we had the 2nd most rainy October of the century and then NOTHING! November had almost no rain and December nothing. Now they say they will start cutting the water again??? WHT? Didn't we make desalination plants for this reason?

by **devil** » Tue Dec 12, 2006 10:16 am

This is just plain, stupid, alarmism on the part of the authorities. Things like this is why they lose all credibility. It is perfectly usual to have a strong anticyclone system stationary in the 2nd ½ of Nov and the 1st ½ of Dec. This year, it has been a little stronger than usual, meaning it has lasted a few days longer. I recorded a high of 1026.4 hPa yesterday. It is beginning to show sign of breaking up (currently 1020.3 hPa) but not fast enough for my liking. We currently have a very high relative humidity (currently 79% at my place) and this has brought the stratus level to about 700 m. I'm hoping the sun isn't strong enough to break this before midday, as it means that rain clouds could form this afternoon if it doesn't dry out too rapidly. However, I'd like to see the barometer drop at least another 10-15 hPa to be sure the anticyclone has been displaced. See http://www.cypenv.org/weather/wx2.htm for the numbers from my weather station which currently forecasts "Increasing clouds with little temperature change: precipitation possible within 24 - 48 hours"; however, such forecasts are only a vague indication based on measured data at the site and do not take into account the data measured elsewhere.

I have measured 150.8 mm of rain this season (we use the 1 Oct as the start of the precipitation year), which is above average. Most rain (65%-70%) falls in the second half of December through to the first half of March, so it is ridiculous to state the the water situation is critical until we see what the total precipitation is, through to April. I would hope for about 400 mm as an average, where I am, so we are already 38% of the way there. If we get an average Dec-Mar rainfall, we will certainly exceed 400 mm for the year. Let's hope for more!

Anyway, as I said, such forecasts are far too early to make, whether by the authorities or myself. At the moment, I'm not too worried.

Incidentally, there is a report on the water mismanagement in this country at http://www.cypenv.org/cyprus_water/

By the way, if you wish to make your own weather measurements, either as a stand-alone system or in a PC with more detail, I have a complete temp/humidity/rain/wind speed/wind direction system for sale at http://www.cyprus-forum.com/viewtopic.php?t=8396 for only £45.

by **andri_cy** » Tue Dec 12, 2006 10:18 am

We had a pretty wet october and a just cold December also. It is actually pretty normal here...

by **cyprusgrump** » Tue Dec 12, 2006 10:26 am

Sotos wrote:This year we had the 2nd most rainy October of the century and then NOTHING! November had almost no rain and December nothing. Now they say they will start cutting the water again??? WHT? Didn't we make desalination plants for this reason?

It seems bizarre that an island surrounded by water and with abundant free energy from the sun can’t desalinate water cheaply.

However, as devil says, it is probably too early to write the winter rains off yet.

by **devil** » Tue Dec 12, 2006 5:27 pm

There is no way to desalinate sea water cheaply.

The usual way is by reverse osmosis which relies on raising the sea water to enormous pressures, passing it through membranes (this is not a filtration, but an effect of liquid interfaces which repel dissolved solids). It has to be done twice to reach full potable quality. The problem here is the energy required.

A way that has occasionally been done in desert countries is solar flash distillation. This is done over, usually, a three-stage process. The sea water is heated to about 80°C in solar collectors and is then pumped through a "shower head" into a partial vacuum chamber, where it mostly boils instantaneously. The vapour is drawn off into a refrigerated condenser and the process is repeated twice more. There are two big disadvantages: the technical one is that the variables in the flashing process are extremely critical (temperature, vacuum pressure, throughput). Too much flashing and the water evaporates totally, leaving a salt dust that is drawn into the condenser, Too little and the efficiency drops like a lead weight. The other disadvantage is that it requires enormous tracts of land because it can operate roughly only 4-5 hours per sunny day. You would need about half the island to supply water for the population! It also is very maintenance-intensive. Energy requirements for the pumping and refrigeration are roughly half that for RO.

The third method is thermal distillation. This would also have to be a triple stage distillation or the still would have to be a complex reflux type. Even if you preheat the salt water by solar means, the energy required to boil it off is twice as high as for RO.

The fourth method is hardly worth mentioning: ion exchange. You pump the salt water through cationic and anionic columns which contain special resins which exchange the salt sodium and chlorine ions for hydrogen and hydroxyl ions respectively. These combine to form water. The water obtained can be extremely pure. The problem is that you would require enormous quantities of hydrochloric acid and sodium hydroxide to regenerate the columns. The cost would be hyper-astronomical.

What can be done to mitigate the water supply problem is outlined in the link I mentioned above.

by **raymanuva** » Tue Dec 12, 2006 6:11 pm

damn you... you jinxed it... here you go, i just washed my car

by **Kikapu** » Tue Dec 12, 2006 6:37 pm

First, if the RoC was smart and wanted to solve the water problem in Cyprus, would do a joint venture with Turkey, and pipe it from Turkey to Cyprus. How hard would it be to lay some heavy plastic Tubes to the bottom of the sea, held down by weights, and pump the water to Cyprus.

Secondly, I would ban all swimming pools from being built anywhere in Cyprus, and would ban all existing ones from being used, if you're within 20 miles from the sea. I can't believe, water is wasted on swimming pools, when you have to whole Ocean to swim in. If the tourist can fly for 4 hours to get to Cypriot beaches, Cypriots can drive half an hour, to go there also.