HOMS COMPONENT

MANUAL RAINGAUGE

1.   Purpose and objectives

     An instrument used for daily rainfall measurement in tropical countries.

2.   Description

     The instrument is the 203mm-diameter rain gauge for daily rainfall measurement. The gauge is made of copper sheet material and consists of the following items:

     i) Collecting funnel and U-tube;
    ii) Collecting can;
   iii) Pouring can;
   iv) A plastic measuring cylinder graduated in fractions of a half- millimetre with a total capacity of
      50mm for the 203mm-diameter rain gauge.

     The mouth of the collecting funnel is a sharp edge bevelled ring of 203mm internal diameter. The funnel is connected to a U-tube through which the rain passes into the collecting can. A negligible amount of rain remains in the U-tube in order to reduce loss by evaporation.

3.   Input

     Actual rainfall.

4.   Output

     Daily rainfall measured by the appointed observer.

5.   Operational requirements and restrictions

     A standard galvanised iron windshield is used in conjunction with the rain gauge to reduce the wind effect on the rainfall measurement. The whole assembly is securely installed at standard convenient height of 1350mm above ground level in order to avoid flooding or disturbance.

6.   Form of presentation

     Technical drawings for local manufacture are available.

7.   Operational experience

     It has been used satisfactorily as a standard instrument for daily rainfall measurement for years by the Drainage and Irrigation Department, Malaysia.

8.   Originator and technical support

     Drainage and Irrigation Department, Malaysia.

9.   Availability

     From the HOMS National Reference Centre for Malaysia.

10.  Conditions on use

     Technical drawings available free of charge. Purchase of the instrument, either complete or as individual items, from the local manufacturers in Malaysia can also be arranged.

Last updated: 28 MAY 99)
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