404
17 Environmental Flow Definition and Management: A Case Study …
17.3.6 Recommended Water Resources Allocation Plan
Scenario modeling allows resource managers to determine the likely outcomes of
different management arrangements. Having decided on an acceptable scenario—in
terms of the management arrangements and the predicted consequences of those
arrangements—the management arrangements should be converted into a regulation
in the form of a water resources allocation plan.
A water resources allocation plan is a regulatory tool that should set the outcomes
sought for the basin, including sustainable levels of water abstraction and identifying the regions or groups entitled to abstract that water (i.e., the cap), the required
reliability for the volumes to be supplied, the desired environmental flows and the
operational and sharing rules to achieve the above requirements.
Scenario 11 delineates the current proposed 2020 arrangements with the modifications of the “sub-optimal” environmental flow rules and the supply rules from
Changtan Reservoir.
(1) Outcomes for the water resources allocation plan
The water resources allocation plan should state its broad desired outcomes. For
Scenario 11, these would primarily be
• To provide certainty to water users by protecting the reliability of their supply by
ensuring that
– urban and industrial users have a reliability of supply greater than X%.
– agricultural users have a reliability of supply greater than Y%.
• To maintain the environmental flows necessary to sustain fish and fisheries within
the basin, by ensuring that
– habitats, water quality, riparian vegetation, and natural geomorphic processes
are protected.
– flows mimic the natural flow pattern to the greatest possible extent, particularly
with respect to low flows and pulses.
(2) Setting water abstraction caps
The water resources allocation plan would set caps on total annual abstractions for
each reservoir and the reaches downstream. The cap would also specify the sectors
that the volume would be available to.
• The total cap on abstractions from Changtan Reservoir would be 664.498 million
m
3 , comprising
– 513.409 million m
3 for urban/industrial users.
– 151.089 million m
3 for irrigation users.
• The total cap on abstractions from Zhuxi Reservoir would be 24.159 million m
3 ,
comprising
17 Environmental Flow Definition and Management: A Case Study …
17.3.6 Recommended Water Resources Allocation Plan
Scenario modeling allows resource managers to determine the likely outcomes of
different management arrangements. Having decided on an acceptable scenario—in
terms of the management arrangements and the predicted consequences of those
arrangements—the management arrangements should be converted into a regulation
in the form of a water resources allocation plan.
A water resources allocation plan is a regulatory tool that should set the outcomes
sought for the basin, including sustainable levels of water abstraction and identifying the regions or groups entitled to abstract that water (i.e., the cap), the required
reliability for the volumes to be supplied, the desired environmental flows and the
operational and sharing rules to achieve the above requirements.
Scenario 11 delineates the current proposed 2020 arrangements with the modifications of the “sub-optimal” environmental flow rules and the supply rules from
Changtan Reservoir.
(1) Outcomes for the water resources allocation plan
The water resources allocation plan should state its broad desired outcomes. For
Scenario 11, these would primarily be
• To provide certainty to water users by protecting the reliability of their supply by
ensuring that
– urban and industrial users have a reliability of supply greater than X%.
– agricultural users have a reliability of supply greater than Y%.
• To maintain the environmental flows necessary to sustain fish and fisheries within
the basin, by ensuring that
– habitats, water quality, riparian vegetation, and natural geomorphic processes
are protected.
– flows mimic the natural flow pattern to the greatest possible extent, particularly
with respect to low flows and pulses.
(2) Setting water abstraction caps
The water resources allocation plan would set caps on total annual abstractions for
each reservoir and the reaches downstream. The cap would also specify the sectors
that the volume would be available to.
• The total cap on abstractions from Changtan Reservoir would be 664.498 million
m
3 , comprising
– 513.409 million m
3 for urban/industrial users.
– 151.089 million m
3 for irrigation users.
• The total cap on abstractions from Zhuxi Reservoir would be 24.159 million m
3 ,
comprising