398
17 Environmental Flow Definition and Management: A Case Study …
Table 17.15 Water transfer
from Zhuxi to Changtan
Scenario
Average annual transfer
Volume (1,000 m 3 )
% of maximum
S2
106,493
80.4
S3
61,356
46.3
S4
106,424
80.3
S5
61,355
46.3
S6
106,493
80.4
S7
–
–
S8
105,676
79.8
S9
121,887
92.0
S10
61,355
46.3
S11
73,451
55.4
NB: Maximum supply rate is 132,495,000 m 3 per annum
Source WET (2007)
Permission granted by WET project subject to proper citation
These scenarios were considered to attempt to improve the reliability of
urban/industrial supplies from Changtan Reservoir. As per Table 17.15, under the
2020 base case (S2), average annual supplies would be about 96% of demand, but
the daily reliability would only be about 82%.
The changed operating arrangements would significantly improve the reliability
of supply to urban/industrial users. Under each of these modified scenarios, the daily
reliability would rise to 93–96%, depending on other variables.
Making this change would reduce average annual supply to irrigation by between
2 and 7% of demand. There are no consequences for users supplied directly from
Zhuxi Reservoir.
17.3.5.4 Effects of Changing the Zhuxi-Changtan Pipeline Operation
Rules
Under planned operating rules for Zhuxi Reservoir, no water will be transferred to
Changtan Reservoir when the Zhuxi Reservoir level falls below 130 m (56.1 million
m
3 ). The modified arrangements in Scenario 9 involve lowering this threshold to
120 m (30.64 million m
3 ). This scenario (S9) was considered in an attempt to improve
the reliabilities of supply for users from Changtan Reservoir.
Table 17.15 shows that these modified arrangements would have minor benefits
for users supplied from Changtan Reservoir, increasing the reliability of achieving
average annual demand by approximately 1%.
These changes would not impact urban/industrial users supplied from Zhuxi
Reservoir. However, the average annual irrigation supplies would reduce in volume
and annual reliability. The relative values of these benefits and costs on the different
users would need to be evaluated to determine whether altering the pipeline operating
rules in this way is appropriate.
17 Environmental Flow Definition and Management: A Case Study …
Table 17.15 Water transfer
from Zhuxi to Changtan
Scenario
Average annual transfer
Volume (1,000 m 3 )
% of maximum
S2
106,493
80.4
S3
61,356
46.3
S4
106,424
80.3
S5
61,355
46.3
S6
106,493
80.4
S7
–
–
S8
105,676
79.8
S9
121,887
92.0
S10
61,355
46.3
S11
73,451
55.4
NB: Maximum supply rate is 132,495,000 m 3 per annum
Source WET (2007)
Permission granted by WET project subject to proper citation
These scenarios were considered to attempt to improve the reliability of
urban/industrial supplies from Changtan Reservoir. As per Table 17.15, under the
2020 base case (S2), average annual supplies would be about 96% of demand, but
the daily reliability would only be about 82%.
The changed operating arrangements would significantly improve the reliability
of supply to urban/industrial users. Under each of these modified scenarios, the daily
reliability would rise to 93–96%, depending on other variables.
Making this change would reduce average annual supply to irrigation by between
2 and 7% of demand. There are no consequences for users supplied directly from
Zhuxi Reservoir.
17.3.5.4 Effects of Changing the Zhuxi-Changtan Pipeline Operation
Rules
Under planned operating rules for Zhuxi Reservoir, no water will be transferred to
Changtan Reservoir when the Zhuxi Reservoir level falls below 130 m (56.1 million
m
3 ). The modified arrangements in Scenario 9 involve lowering this threshold to
120 m (30.64 million m
3 ). This scenario (S9) was considered in an attempt to improve
the reliabilities of supply for users from Changtan Reservoir.
Table 17.15 shows that these modified arrangements would have minor benefits
for users supplied from Changtan Reservoir, increasing the reliability of achieving
average annual demand by approximately 1%.
These changes would not impact urban/industrial users supplied from Zhuxi
Reservoir. However, the average annual irrigation supplies would reduce in volume
and annual reliability. The relative values of these benefits and costs on the different
users would need to be evaluated to determine whether altering the pipeline operating
rules in this way is appropriate.