11.18 The routine maintenance of access roads, catchwaters, control gates, treatment works, pumping stations, staff quarters and depots, and the maintenance and cleaning of service reservoirs continued.
11.19 Two heavy rainstorms, in May and June, caused widespread damage to Waterworks installations, the estimated cost of repairs being $3.5 million. Of this, damage estimated at $1 million to headworks installations occurred in May, whereas the more severe rainstorm in June caused damage to the value of $2.5 million. Damage to installations resulted in the interruption of supplies to Stanley for almost a day and the island of Cheung Chau was on restricted supply for three days whilst repairs were carried out.
Operations Sub-Division
11.20 The Government I.C.L. 1903A series computer is used in connection with reservoir system operations, the determination of consumption statistics and other supply criteria. During the year, a computer programme for the determination of reservoir draw-off rates was introduced and work was completed on the development of reservoir regulation rules. The 1971 trade consumption figures were analysed on the basis of supply zones and the nature of the trades. Work continued on the per-capita consumption study and a review of pumping station capacity throughout the system was completed. A number of routine reports were prepared including a comprehensive report on reservoir yields and consumption in major supply zones over the period 1969 to 1972.
Hydrological Section
11.21 Routine maintenance of 123 rain gauging stations, 23 stream and reservoir gauging stations and one evaporation station continued. In connection with the High Island Water Scheme, weekly readings of water levels at 19 observation wells and 13 low flow weirs also continued.
11.22 Data abstraction and preparation of Volume VII in the series of 'Hong Kong Rainfall and Run-off' and the preparation work for printing a revision of 'Gross Yield of Hong Kong Reservoirs' continued. A study employing the aid of a computer is also being made on the gross yields and pumpable yields of the River Indus flood pumping scheme.
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