Evaporation Rates at Jeddah (KSA) Location

Rate of evaporation depends on the ambient wet bulb temperature. When the ambient air is dry evaporative cooling is faster.

If you go the route of measuring evaporative rates from a pan, do so with at least 3 pans. You should also use a portable 24/7 weather station with data recorder that measures the relative humidity, temperature and wind speeds as it may take several days for evaporation to occur significantly/measurable.....it all depends on the weather that is occurring at that specific time period. Also, remember that doing this only once and not over a long period of time only presents very limited data and should be considered only a "snap shot" that is of limited utility from a design perspective.

Check for data available from the nearest airport to see if they have constant weather data recording.....or find out if there is a nearby university or governmental (Saudi Arabia, correct?) agricultural department that can provide you with long-term weather data including evaporative rates over several years period of time.

HTH!!!

GA CaptMouse, I fully agree with you that evaporation rate greatly depends on the relative humidity, ambient temperature and wind speeds. These three parameters are varying widely on daily as well as on seasonal basis. If these three parameters are available over several years period of time, but evaporation rate is not available then I suggest to try following method.

Take a large pan of area 1 sq.m with water of same quality and keep it on weighing platform. Arrange necessary instrumentation for measuring and on-line recording of weight, water temperature, ambient temperature, relative humidity and wind speed. Analyse the collected data after few days to check how these parameters affect evaporation rate. Now with the available long time data for these parameters extrapolate the evaporation rate.

Thank you so much for all your kind guidance and help. As per the information i have received from my colleagues and other engineers, there is a set of meteorological data for all locations in saudi arabia available in which they give the approved and accepted information of evaporation rates, rainfall data, temperatures, wind speeds and directions etc which can be used for design of civil/structural elements/facilities. These data are published by the responsible government authorities on yearly basis.

If there's anyone who had previous working experience on projects in saudi arabia, then these data must be available with them. I am trying to contact with one of them as there are many ongoing and recently completed projects in saudi arabia.

www.waterandclimatechange.eu/evaporation/average-monthly-1985-1

That looked hopeful, but alas the link didn't work.

Evaporation in Average Year - Maps - Evaporation - Evaporation

I do not know, but have some suggestion of where to seek an answer.

Check websites for cooling tower manufacturers. Check for operating information on cooling towers. They might have information for calculating required water make up for operating cooling towers based on tower size, heat load, and climatic data.

One issue that may come up during plant operation is pond water quality. As the pond evaporates for cooling, the water quality will diminish due to concentration of dissolved solids and other contaminants. Keep this in mind for corrosion and scaling problems with plant equipment.

http://nepis.epa.gov/Exe/ZyNET.exe/9100H0DE.txt?ZyActionD=ZyDocument&Client=EPA&Index=Prior%20to%201976&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C70THRU75%5CTXT%5C00000012%5C9100H0DE.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=5

Astract of an EPA report

http://www.ask.com/web?q=how+to+estimate+rate+of+evaporation+from+a+cooling+pond%3F&search=&qsrc=0&o=100000031&l=dis&gct=serp Ask.com web search results

Hope these links provided the mathematical models that would work for you.

This may help

http://www.kau.edu.sa/Files/320/Researches/48196_19423.pdf

Also look up evaporation rates of water in saudi arabia.

Sorry about that! Try this: www.waterandclimatechange.eu

After you get the web site click on evaporation rates.

Interesting, but this depends largely on the availability of water to be evaporated, hence a low evaporation rate in the Sahara. The rate should be quite a bit higher if lots of water could be pumped there.

The other issue is that this pond is associated with a power plant, so presumably the water is heated above ambient temperature and should have a higher than average evaporation rate.

While doing an evaporative or spray pond, you could trick it out in "dancing waters" fashion with movable fountain nozzles and laser effects. Add music and food service, and you could have a revenue-generating entertainment attraction. Hafla time!

Here is some current research that may answer this for future readers.

https://www.researchgate.net/publication/303436020_Analysis_of_Potential_of_Evapotranspiration_in_different_Cities_of_Saudi_Arabia