Water Density

Can you imagine a world without water! Water is strange! We need it for almost everything we do to be alive. Personally I was so happy after reading the news that about 2 percent of the soil of the surface of Mars is made up of water. 

We  know that density of water is changing with temperature, pressure and also salinity. Commonly in our calculation we consider having fresh water (with very low salinity) and 1 bar pressure. In this situation the maximum density of water is around 4 degree Celsius. 

I made a small software to calculate the density of water based on its temperature. You can download it here (32, 64). Please let me know if you have any questions or want me to add more features to this software. 

Mamloo Dam construction

I was director of SACES (Scientific Association of Civil Engineering Students) at University of Tehran and we planned many talks, field trips and colloquiums. In one of our filed trips we visited a soil dam 45 km southeast of Tehran. I was looking to the map of rivers around Tehran today and found that they finished the construction of the dam and already using it. Name of the dam is Mamloo soil dam and it receives water from two rivers from north and northeast of Varamin; and the main river is Jajrood river which supplies some water of metropolitan Tehran. You can look at the location of the dam here (google maps) or download the kmz file here (google earth). Here are some pictures before finishing the construction when we visited the site (Pictures are big in size so you may download them if you want to have a closer look).

Why water infrastructure

Somehow history of human begins with water.  Ancient civilizations developed near water resources like springs, lakes and rivers, which were sources of clean water on that time. All of us heard about great civilizations on the bank of Mesopotamia, Nile rive and Indus river. 

Water has a huge impact on human history and having clean and safe water always has been a big concern and will be. In arid areas people knows the value of water and they did very interesting works to bring water to their home. They dig water wells and Qanats and much of the population in that areas depended directly to this water. One of the oldest and largest known Qanat is in Iran and still after 2,700 years providing drinking and agricultural water to nearly 40,000 people. Also there is a two story Qanat in Ardestan which is constructed 800 years ago and has 60 l/s flow.

In the picture you can see a Qanat in Hormozgan province from Sassanid era.

Besides drinking water and using it for cleaning and aggregation, human tried to use water for other purposes. To providing energy like watermills, to having cool flow in windcatchers, for measuring time and ....

In the pictures below you can see water clock and the clay tablet for water clock calculations from Babylon period.

Beside of these, there is a great history on dams and how human tried to reserve water for his future. 

Blow is the picture of the Saad El Kafara dam which is built by ancient Egyptians around 2650 BC.

 I will try to have a post about dams later.