448
10-
Estimate of amount of
storage
required fo maintain a
an estimate of the probable receipts from rain and the estimated expenditure, during the coming dry months, and at the end of the water-year he should submit a balance-sheet, shewing the actual transactions of the past water-year.
28. The following statement, arranged in debtor and creditor form, serves to give a general idea of the amount of storage which must be provided in order to maintain a uniform supply equal to that due to the average rainfall of a long cycle. supply equal Or, in other words, to carry forward, from years of abundance, to supplement deficiencies during years of drought. It is evident that the maximum supply that can be maintained, at a constant rate, over a given cycle of years, is that due to the average rainfall, during the said cycle. To do this there must be sufficient storage in order that there shall be no overflow, even in the wettest year.
to average
of a cycle.
Now, the average rainfall at the Observatory, for 17 consecutive years, amounted. to 85 inches, nearly.
To ascertain the amount of storage the account has been made out for One Acre only, so as to avoid inconveniently large figures, and, for the same reason, the observed rainfalls have been taken, to the nearest inch only. It has been also assumed that 60 per cent. of the rainfall is available for collection.
Then the average supply that one acre would given is :—
Gallons
22,635 × 85′′ × 0·6—1,154,385 gallons per annum.
3,162 gallons a day.
The problem, therefore, is to see how many days' stock there must be in hand at the end of each water-year.
Water-works in Account with Rain for One Acre, 60 % being assumed as available.
Gallons.
1884-95
Dr. to stock in hand, assumed, 250,000
Cr. by Consumption,
Gallons.
...1,154,385
25
to Rain 82",
..1,113,642
>>
by Balance,
209,257
1,363,642
1,363,642
1885-86
Dr. to Balance,
209,257
Cr. by Consumption,
..1,154,385
"
to Rain 100",
.1,358,100
"1
by Balance,
412,972
1,567,357
1,567,357
1886-87 Dr. to Brought forward,
to Rain 76",
*
412,972 ..1,032,156
Cr. by Consumption,
...1,154,385
"
by Balance,
290,743
1,445,128
1,445,128
1887-88 Dr. to Brought forward,
to Rain 69",
"
}
290,743 937,089
Cr. by Consumption,
...1,154,385
+
by Balance,
73,447
1,227,832
1,227,832
1888-89 - Dr. to Brought forward,
to Rain 99", ..
99
73,447 ..1,344,519
Cr. by Consumption,
...1,154,385
35
by Balance
263.58]
1,417,966
1,417.966
1889-90 Dr. to Brought forward,
to Rain 103",
"
263,581 ...1,534,653
Cr. by Consumption,
...1,154,385
""
by Balance,
643,849
1,798,234
1,798,284
1890-91
Dr. to Brought forward,
་་
to Rain 67", ...
613,849 909,927
Cr. by Consumption.
25
by Balance,
T
...
...1,154,385 399,391
1,553,776
1,553,776
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