Monday, May 19, 2014

MEASURING UP THE WATER




Water is everywhere on and in the earth. We experience water in three phases, Vapour, Liquid and Ice. The transition from one to another phase occurs well within our perception range. Water in all its three forms is a transparent matter, but we see it due to presence of air and other miscible as well immiscible matter in it.





If all of Earth's water that is in oceans, icecaps and glaciers, lakes, rivers, groundwater, and atmosphere were put into a ball then it would add up to about 1,386 million cubic kilometres (=ball of dia 1385 kilometres). All the water vapour in atmosphere if were to turn into liquid state, it can cover the Earth’s surface by just 25mm depth. The ‘residence’ time of a water molecule in the troposphere is about 9 to 10 days.

Water vapour is continuously generated by two processes, the evaporation of water and the sublimation of ice. The vapour is removed by condensation. Water on evaporation takes away some heat with it, causing evaporative cooling. Conversely when the water vapour condenses onto a surface, a net warming occurs on that surface. Vapour is replenished by evaporation, from seas, lakes, rivers, moist earth, combustion, respiration, volcanic eruptions, the transpiration of plants, biological and geological processes. Humidity varies from 0 grams per cubic metre in dry air to 30 grams per cubic metre. The water content of the atmosphere as a whole is constantly depleted by precipitation.

Water is used for drinking, cooking, bathing, washing, gardening, farming, fishing, transports, cooling, fire-fighting, industrial processes, etc. While using the water, we not only foul it by soils, sediments and chemicals but warm it up.

The transition of water from one phase to another is seen in terms of quantum and the rate at which it occurs. The change is affected by the atmospheric pressure and temperature. Water like any other matter is affected by the gravity which sets in a motion towards the Earth, and in its liquid form by the flows from a higher to lower datum. The rate of flow or water in motion is measured as a rate of passage through an orifice (a measured section) with time as the constant. 


Water as a Liquid is measured by its Volume and sometimes by its Weight. 1 cubic mt of water is 1000 litres of water = 1000 kg

Rainfall: Rainfall is measured in a typical standard rain gauge as prescribed by the Indian Meteorological Department. Typical measurements are taken at 8.30 a.m. in the morning and reported as mm of rain. With 10 mm rainfalls (standard reportage) over a roof area of 100 Sq. mts will yield = 1000 lts of water.

Rain Water measurement Equipment

Flow rate of water provides the measure for water in motion. Cusec = 1 cubic feet of water flow per second / In SI units it is measured as cubic metres of flow per second. If 1 cusec of water is released from a dam for the whole day, 2.45 million litres of water would flow out in 24 hours.

Water temperature is important for use-intake as well as discharge as effluent. The temperature of intake water affects the efficiency of power plants, industrial units and HVAC units. The discharge temperature affects the ability of water to hold oxygen, growth of organisms, and nature of pollutants.

pH level of water reflects the acidity or alkalinity of water. In a range of 0-14, 7 is neutral, less than 7 indicate acidity, and pH of greater than 7 indicates an alkalinity. It also suggests the relative amount of free hydrogen and hydroxyl ions in the water. Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic.

Specific conductance is a measure to conduct an electrical current. It is highly dependent on the amount of dissolved solids (such as salt) in the water. Pure water, such as distilled water, will have a very low specific conductance, and sea water will have high specific conductance. Rainwater often dissolves airborne gasses and airborne dust while it is in the air, and thus often has higher specific conductance than distilled water. Dissolved solids affect the taste aspect of water such as an unpleasant taste or odour or may cause gastrointestinal problems. High dissolved-solids reduce the flow properties through surface deposition in pipes and plumbing fixtures. It can be removed by reverse osmosis and other water treatments.

Turbidity is the amount of particulate matter that is suspended in water. Material that causes water to be turbid includes: clay, silt, finely divided organic and inorganic matter, soluble coloured organic compounds, plankton and microscopic organisms. Turbidity can be reduced by settlement and filtration devices. The amount of dissolved calcium and magnesium in water determines its "hardness." Water hardness varies throughout the United States. If you live in an area where the water is "soft," then you may never have even heard of water hardness.

Suspended sediment is the amount of soil particles in water. Fast-moving water is likely to pick a lot more soil particles then slow moving or still water.

Dissolved oxygen in water is important for the organisms and creatures in lakes, rivers, and oceans. 

 Water Standards: Indian Standards for drinking water are specified in IS 10500

Executive summary and recommendations of the committee on the pesticides residue in packaged drinking water and packaged natural water.


Mineral Water The Food and Drug Administration defines mineral water as water “containing not less than 250 ppm total dissolved solids that originate from a geologically and physically protected underground water source.” (Water originating from an underground source but containing less than 250 parts per million dissolved minerals can be labelled spring water.)


Perrier is a popular brand of sparkling mineral water bottled in Vergèze, France. Although the water from the spring in Vergèze is naturally carbonated, the Perrier plant collects the water and the carbonic gas from the spring separately, filters the gas, and then recombines the water and gas; this process results in a more consistent product. Perrier is acidic, with a pH around 6, and it contains calcium, chloride, bicarbonate, fluoride, magnesium, nitrate, potassium, sodium, and sulfates.


San Pellegrino, stylized S. Pellegrino, is a popular brand of sparkling mineral water bottled in San Pellegrino Terme, Italy. The water from the spring is not naturally carbonated; the San Pellegrino plant adds “carbonation from natural origin.” San Pellegrino is acidic, with a pH of 5.6, and it contains the same minerals as Perrier, plus lithium, silica, and strontium.

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