The Commonwealth Bureau of Meteorology is primarily responsible, inter afia , for the measurement of rainfall in Australia. The Bureau currently maintains some 7,500 rain gauges, but it is estimated that over 13.000 are required to provide an adequate national network. A continuous record of the intensity of rainfall is made by an instrument called a pluviograph. About 500 of the existing 7,500 gauges are pluviographs and a further 1,200 pluviographs are estimated to be required. At present some 1,300 gauges are installed.
Current plans call for the completion of the basic network within ten years.
Water levels can be recorded continuously by installing instruments at the gauging site. The discharge is obtained by visiting the site and measuring the velocity of the stream in vertical sections across the stream. Knowing the sectional area enables the discharge corresponding to the height of the stream at that particular time to be calculated. In order to determine this relationship it is necessary to carry out measurements at the gauging site over a range of discharge conditions including Periods of flood. The measurement of underground water is a more complex task than is the measurement of rainfall and river discharge.