XN000022-1977-07-07 — Page 4

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THURSDAY, JULY 7, 1977

WATER CONSUMPTION REQUIREMENTS WELL-CALCULATED

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THE WATER SUPPLIES DEPARTMENT USES COMPUTERS TO DETERMINE IF AND WHEN WATER RESTRICTIONS SHOULD BE IMPOSED, THE DEPARTMENT'S CHIEF ENGINEER (SUPPLY), MR. K.L. WONG SAID TODAY.

MR. WONG SAID THAT IN ANALYSING HONG KONG'S WATER SITUATION, THE WATER SUPPLIES DEPARTMENT IS NOT CONTENT JUST TO SEE THAT THE WATER IN STORAGE IS ADEQUATE TO LAST FOR THREE OR FOUR MONTHS, BUT LOOKS AHEAD FOR AT LEAST NINE TO 12 MONTHS.

SPEAKING AT A LUNCH-TIME MEETING OF THE Y'S MEN CLUB OF H.K., MR. WONG SAID USING A COMPUTER, THE WATER SUPPLIES DEPARTMENT TAKES THE AMOUNT OF WATER AVAILABLE AT ANY POINT IN TIME, AND POSTULATES DIFFERENT COMBINATIONS OF RESTRICTION PLANS AND STUDIES THE ASSOCIATED CONSEQUENCES OVER THE NEXT NINE TO 12 MONTHS.

+WE COMPUTE THE VARIOUS PROBABILITIES TO SEE WHAT ARE THE CHANCES OF BEING UNABLE TO PROVIDE AT LEAST A SUPPLY OF FOUR HOURS EACH DAY IN THE COMING MONTHS AND WE CAN ALSO COMPUTE THE PROBABILITIES OF THE RESERVOIRS OVERFLOWING IF IT SHOULD RAIN HEAVILY.+

MR. WONG NOTED THAT PAST RAINFALL AND RUNOFF RECORDS ARE USED IN THIS ANALYSIS, AND BECAUSE OF THE ENORMOUS AMOUNT OF

CALCULATIONS INVOLVED, THE AID OF A COMPUTER IS ALMOST ESSENTIAL.

+ IN THE WET SEASON, MR. WONG CONTINUED, THE SITUATION IS VERY DYNAMIC AND CAN CHANGE DRAMATICALLY WHEN IT RAINS.

+ IT IS THEREFORE UNDER CONSTANT REVIEW TO SEE IF THE SITUATION WARRANTS A DIFFERENT COURSE OF ACTION.+

HE SAID THAT IN ORDER TO MANAGE HONG KONG'S WATER RESOURCES EFFICIENTLY, THE WATER SUPPLIES DEPARTMENT MUST HAVE ACCURATE KNOWLEDGE OF THE QUANTITY OF WATER STORED IN EACH INDIVIDUAL RESERVOIR, THE WATER CONSUMPTION BY AREA AND BY TYPE, THE ESTIMATED FUTURE DEMAND, THE CATCHMENT CHARACTERISTICS, AND THE RAINFALL/RUNOFF PATTERN, AND PROBABILITIES.

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TO COLLECT THE DATA ON THE RESERVOIR STORAGES, FIELD STAFF GO OUT EACH DAY TO TAKE THE WATER LEVEL IN EACH OF THE 16 IMPOUNDING RESERVOIRS. AT THE SAME TIME THE STAFF ALSO TAKE READINGS OF THE RAIN GAUGES INSTALLED WITHIN CATCHMENT AREAS.

THESE READINGS ARE THEN TRANSMITTED TO THE STATISTICS SECTION OF THE WATER SUPPLIES DEPARTMENT WHERE CALCULATIONS ARE MADE TO COMPUTE THE RESERVOIR STORAGES, AND IF THERE HAS BEEN RAINFALL, THE QUANTITY OF WATER COLLECTED.

/IN ADDITION