Evaporation can now be measured: Indian scientists

Chennai: Evaporation has now been simplified, thanks to a latest device developed by a team of scientists at Indian Institute of Science (IISc).

In a statement here, IISc said, ‘The device is a more efficient and inexpensive way to measure evaporation when compared with existing methods’.

“Our method allows you to get a much more realistic measure of transpiration from plants and evaporation from soils”, said Jaywant H Arakeri, Professor in the Department of Mechanical Engineering, IISc, and senior author of the study recently published in the Journal of Hydrology.

Being able to measure the evaporation rate is useful for farmers to gauge water requirements for their fields and in weather stations to characterise the local atmospheric condition. It is also widely used by botanists to study the dynamics underlying transpiration by plants.

Currently, pan evaporimeters are the most commonly used devices to measure evaporation rates.

The disadvantages (of existing methods) are that the evaporation rates are for one whole day, and over a large area (one square metre). And one needs an open ground to place the device.

The proposed device however consists of a filter paper connected to a capillary tube that takes water from a reservoir to the filter paper, thereby wetting it and thus mimicking an evaporating water surface. By measuring the distance travelled by the lower meniscus in the capillary tube over a couple of minutes, the evaporation rate is estimated.

The innovation lies in being able to measure the very small amount (about one microlitre) of water that is lost in evaporation from the surface in a minute, according to IISc.


NT Bureau