An automatic reading rain gauge and a computerized recording system for measurement of rainfall.

Abstract

There are few recording type rain gaugeð€€‘used in Sri Lanka to measure rainfall intensity, duration and onset. However it is not affordable due to high initial, installation and maintenance costs. Therefore, Present research is aimed to design, construction and performance testing of a low cost Automatic Computer Recording Rain gauge System (ACRRS), with facilities to change minimum reading and rain capturing funnel diameter. This system stores electronically measured rainfall data in a database and displays rainfall data on computer graph and report forms. The bottom open technique, which opens the bottom of a bucket is a new method used for rain gauges. An electronic sensor circuit is used to measure the rainfall height. There measured rainfall data sends to the computer via RS232 port by converting it into digital bit string. Data conversion and RS232 port communication are done by a Microcontroller based electronic circuit. The performances of the new rain gauge were tested in the laboratory and in the meteorological station at Mapalana. In the laboratory test, a known volume of water is added at a given intensity, in to the rainfall receiving funnel. Field validation of the rain gauge is conducted in the Meteorological station comparing it with Tipping Bucket and Standard rain gauges. It was detected that the error percentages of Laboratory test and Field test data for new rain gauge are less than 5%. Therefore it can be concluded that the new rain gauge measures rainfall accurately.