What is Symons rain gauge?
Symons rain gauge: The non-recording type gauge mostly used in the world is Symon’s gauge. Non-recording gauges don’t record the rain but only collect the rain. Once the rain is collected, it is measured using a graduated cylinder.
The volume of rain collected in the measuring cylinder directly depicts the rainfall volume in cm of water depth i.e. the volume of water collected in cm divided by the area of the hole that admits the light of the gauge in cm2 is equal to the depth of rainfall in cm.
The receiver also known as connecting bottle has a capacity to measure 175 mm of rain. In the region of huge amounts of rainfall, a rain gauge with collectors having a capacity of 375 mm or 1000 mm capacity is used to measure the rainfall depths.
Non-recording type rain gauge also known as rain gauge measures the amount of rainfall only and it fails to measure the variations.
In order to record the beginning and end of the rain and to measure the intensity of rainfall, a continuous recording of rainfall with time is required, for this purpose, we have to use the recording rain gauges.
In Symon’s rain gauge, the concrete blocks which act as a foundation are 600 mm x 600 mm x 600 mm.
Also read: Rainwater Harvesting System
Symons rain gauge diagram
- It consists of the circular receiving area which is 127mm in diameter and connected to a funnel.
- The rim of the collector is set at a height of 30.5 cm above ground level.
- The funnel discharges the rainfall into receiving funnel.
- The funnels and receiving vessels are housed in a metallic container.
- The receiving bottle normally holds a maximum of 10 cm of rain and in case of heavy rainfall, the measurement must be done frequently.
- The last reading must be taken at 8:30 AM and the sum of the previous readings in the last 24 hours entered as the total rainfall of the day.
Advantage of Symon rain gauge
- It helps to measure all forms of precipitation or rainfall which comprised snow and rain.
- Removing its funnel collector permits the accumulation of solid rainfall and also plays a significant role in estimating cold climates.
- Rainwater collected is measured on daily basis.
Disadvantage of Symon rain gauge
- This type of gauge only collects rain.
- This gauge does not record and measure the rainfall simultaneously.
- Symons rain gauge only shows how much rain has fallen.
- One of the main disadvantages of Symons rain gauge is that we cannot determine when the rain began, the intensity with which the rain was falling, when the rain stopped and variation in the intensity of rain throughout the rainy period.
Least count of Symons rain gauge
The smallest division on the Symons rain gauge is 0.2mm. The rainfall can be estimated to be approximately 0.1mm.