17.3 Environmental Flow Assessment and Water Resources…
405
– 13.514 million m
3 for urban/industrial users.
– 10.645 million m
3 for irrigation users.
(3) Setting water-sharing rules
There will be periods of water shortage when users will not receive 100% of the
entitlements under their permits. To manage these situations fairly, water-sharing
rules need to be defined in the water resources allocation plan. These are the rules
that determine the proportion of available water that different groups of users will
receive during shortages.
The water-sharing rules for the current example would principally involve the
rules that determine the point at which different groups will not be supplied. The
details of this shall be set by the operational arrangements (e.g., release rules) for the
Zhuxi and Changtan Reservoirs.
(4) Setting reservoir release rules
Reservoir release rules need to be clearly defined in a water resources allocation
plan. These rules ensure that the infrastructure operator has clear guidance on what is
required in operating the reservoir to ensure that the plan’s supply and environmental
outcomes are achieved. Operational rules to be set in the water resources allocation
plan for Zhuxi reservoir would include.
• No water is to be transferred to Changtan Reservoir when the Zhuxi Reservoir
level falls below 130 m (56.1 million m
3 ).
• Water supply for irrigation demands would cease when the dam water level falls
below 122 m (34.82 million m
3 ).
• Hydropower stations would cease operations when the dam water level falls below
120 m (30.64 million m
3 ).
• Water supply for urban demand would continue until the dam water level reaches
the inactive water level of 100 m (5.14 million m
3 ).
Similarly, the modified operating arrangements for Changtan Reservoir under
Scenario 11 would provide the following release rules:
• When the water level falls to 15.05 m (12 million m
3 ), urban/industrial supplies
are to be restricted by releasing water at a rate of 3 m
3 per s (259,000 m
3 per day).
• When the water level is between 21.05 m (72 million m
3 ) and 23.05 m (104
million m
3 ), the maximum irrigation release is restricted to 12 m
3 per s (1 million
m
3 per day).
• When the water level falls to 21.05 m (72 million m
3 ), irrigation water supply is
reduced to zero.
• The hydropower station is to cease operations when the water level falls below
23.05 m (104 million m
3 ). Between 23.05 and 24.05 m, the maximum release for
hydropower is restricted to 25 m
3 per s (2.16 million m
3 per day). Between 24.05
and 26.05 m, the maximum release is restricted to 50 m
3 per s (4.3 million m
3 per
day).
405
– 13.514 million m
3 for urban/industrial users.
– 10.645 million m
3 for irrigation users.
(3) Setting water-sharing rules
There will be periods of water shortage when users will not receive 100% of the
entitlements under their permits. To manage these situations fairly, water-sharing
rules need to be defined in the water resources allocation plan. These are the rules
that determine the proportion of available water that different groups of users will
receive during shortages.
The water-sharing rules for the current example would principally involve the
rules that determine the point at which different groups will not be supplied. The
details of this shall be set by the operational arrangements (e.g., release rules) for the
Zhuxi and Changtan Reservoirs.
(4) Setting reservoir release rules
Reservoir release rules need to be clearly defined in a water resources allocation
plan. These rules ensure that the infrastructure operator has clear guidance on what is
required in operating the reservoir to ensure that the plan’s supply and environmental
outcomes are achieved. Operational rules to be set in the water resources allocation
plan for Zhuxi reservoir would include.
• No water is to be transferred to Changtan Reservoir when the Zhuxi Reservoir
level falls below 130 m (56.1 million m
3 ).
• Water supply for irrigation demands would cease when the dam water level falls
below 122 m (34.82 million m
3 ).
• Hydropower stations would cease operations when the dam water level falls below
120 m (30.64 million m
3 ).
• Water supply for urban demand would continue until the dam water level reaches
the inactive water level of 100 m (5.14 million m
3 ).
Similarly, the modified operating arrangements for Changtan Reservoir under
Scenario 11 would provide the following release rules:
• When the water level falls to 15.05 m (12 million m
3 ), urban/industrial supplies
are to be restricted by releasing water at a rate of 3 m
3 per s (259,000 m
3 per day).
• When the water level is between 21.05 m (72 million m
3 ) and 23.05 m (104
million m
3 ), the maximum irrigation release is restricted to 12 m
3 per s (1 million
m
3 per day).
• When the water level falls to 21.05 m (72 million m
3 ), irrigation water supply is
reduced to zero.
• The hydropower station is to cease operations when the water level falls below
23.05 m (104 million m
3 ). Between 23.05 and 24.05 m, the maximum release for
hydropower is restricted to 25 m
3 per s (2.16 million m
3 per day). Between 24.05
and 26.05 m, the maximum release is restricted to 50 m
3 per s (4.3 million m
3 per
day).