17.3 Environmental Flow Assessment and Water Resources…
379
proximity to the channel were estimated at 571 m
3 /s (instantaneous). Overbank flows
are less likely to be important for fish in Reach 1 due to the absence of extensive
floodplain areas and so should occur on average once every two years.
(2) Reach 2 Recommendations
See Table 17.7.
Low Flow
Due to marked seasonal variation in natural low flows over the dry season, separate low flow components have been specified for October–January (1.3 m
3 /s) and
February–March (3.4 m
3 /s). The higher flow for February–March ensures that the
recommended regime remains within the historical range.
Low Flow Pulse
Two periodic flow pulses of 53 m
3 /s, each lasting for two consecutive days, are
recommended for Reach 2.
Overbank Flow
Overbank flows may play a role in allowing fish to access floodplain habitats in the
lower reaches of Zhu Creek, where a more extensive floodplain occurs. As such,
overbank flows should on average occur a little more than once every two years in
Reach 2.
(3) Reach 3 Recommendations
The environmental flow recommendations for Reach 3 are provided in Table 17.8.
In this section of Yong’an Creek, flows will reflect overall levels of water extraction
from the entire upstream catchment, not just diversions from Zhu Creek.
Low Flow
Due to marked seasonal variation in natural low flows over the dry season, separate
low flows have been specified for October–January (6.8 m
3 /s) and February–March
(17.3 m
3 /s).
Low Flow Pulse
The low flow pulse component was assumed to correspond with the inundation of
the lower bench (Bench 1) identified in the cross-sectional conducted in Reach 3
(Fig. 17.5). The low flow pulses should occur approximately four times each year
from October–March (natural frequency), and each event should last four consecutive
days (natural median duration).
High Flow Pulse
The low flow pulse component was assumed to correspond with the inundation of
the middle bench (Bench 2) identified in the cross section for this reach (Fig. 17.5).
High flow pulses should occur six times every year (natural frequency) from April–
September, with each event lasting seven consecutive days (natural median duration).
379
proximity to the channel were estimated at 571 m
3 /s (instantaneous). Overbank flows
are less likely to be important for fish in Reach 1 due to the absence of extensive
floodplain areas and so should occur on average once every two years.
(2) Reach 2 Recommendations
See Table 17.7.
Low Flow
Due to marked seasonal variation in natural low flows over the dry season, separate low flow components have been specified for October–January (1.3 m
3 /s) and
February–March (3.4 m
3 /s). The higher flow for February–March ensures that the
recommended regime remains within the historical range.
Low Flow Pulse
Two periodic flow pulses of 53 m
3 /s, each lasting for two consecutive days, are
recommended for Reach 2.
Overbank Flow
Overbank flows may play a role in allowing fish to access floodplain habitats in the
lower reaches of Zhu Creek, where a more extensive floodplain occurs. As such,
overbank flows should on average occur a little more than once every two years in
Reach 2.
(3) Reach 3 Recommendations
The environmental flow recommendations for Reach 3 are provided in Table 17.8.
In this section of Yong’an Creek, flows will reflect overall levels of water extraction
from the entire upstream catchment, not just diversions from Zhu Creek.
Low Flow
Due to marked seasonal variation in natural low flows over the dry season, separate
low flows have been specified for October–January (6.8 m
3 /s) and February–March
(17.3 m
3 /s).
Low Flow Pulse
The low flow pulse component was assumed to correspond with the inundation of
the lower bench (Bench 1) identified in the cross-sectional conducted in Reach 3
(Fig. 17.5). The low flow pulses should occur approximately four times each year
from October–March (natural frequency), and each event should last four consecutive
days (natural median duration).
High Flow Pulse
The low flow pulse component was assumed to correspond with the inundation of
the middle bench (Bench 2) identified in the cross section for this reach (Fig. 17.5).
High flow pulses should occur six times every year (natural frequency) from April–
September, with each event lasting seven consecutive days (natural median duration).