Question

Which one of the following points should be kept in mind while selecting the site for a rain gauge station?

The site where a rain gauge is set up should be close to a meteorological observatory.

The rain gauge should be on the top of a hill.

A fence, if erected to protect the rain gauge from cattle etc. should be located within twice of the height of the fence.

The distance between the rain gauge and the nearest object should be atleat twice the height of the object.

Answer ( Option D)

The distance between the rain gauge and the nearest object should be atleat twice the height of the object.

Solution

As per IS 4986 : 2002,

The amount of precipitation collected by a raingauge depends on its exposure and the details given below shall be specially taken into consideration in selecting a suitable site:

(i) The gauge shall be placed on level ground not upon a slope or terrace and never on a wall or roof.

(ii) On no account the raingauge shall be placed on a slope such that the ground falls away steeply on the side of the prevailing wind.

(iii) The distance between the raingauge and the nearest object should generally be four times the height of the object, but never shall be less than twice the height of the object.

(iv) Great care shall be taken at mountain and coastal stations that the gauges are not unduly exposed to the sweep of the wind. A belt of trees or a wall on the side of the prevailing wind at a distance, preferably four times its own height but exceeding at least twice its height, shall form an efficient shelter.

(v) Where the observations have to be made on an extensive sloping surface such as the side of a mountain, effort should be made to expose the gauge on a smooth side which is sufficiently large in area and whose slope and orientaion correspond to the average slope and orientation of the surrounding. The raingauge should be installed on stable slopes on hilly areas.