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17 Environmental Flow Definition and Management: A Case Study …
Table 17.4 Vegetation-related environmental flow objectives with flow components and hydraulic
criteria
Environmental flow
objective
Reach
Flow component Hydraulic criteria Timing
Scour vegetation
from gravel bars and
transfer organic
material to the
stream
1, 2, 3
High flow pulse
Sufficient to scour
vegetation
High flow season
(Apr–Sep)
Maintain vegetation
neighboring the river
channels (riparian
vegetation)
1, 2, 3, 4, 5 Overbank flow
Morphologically
defined levels
Anytime
Prevent
encroachment from
terrestrial species
into river channels
(e.g., Salix sp.)
1, 2, 3
Bankfull
Critical shear
stress
Anytime
Maintain floodplain
wetland
communities
(perennial and
annual species)
1, 2, 3, 4, 5 Overbank flow
Morphologically
defined levels
High flow season
(Apr–Sep)
Source WET (2007)
Permission granted by WET project subject to proper citation
Table 17.5 Geomorphology-related environmental flow objectives with flow components and
hydraulic criteria
Environmental flow
objective
Reach
Flow component
Hydraulic criteria
Timing
Maintain channel
form
1, 2, 3, 4 Bankfull
Morphologically
defined levels
Anytime
Flush fine sediment
from surface of bed
1, 2, 3, 4 Low flow pulse and
High flow pulse
Critical shear stress
to mobilize silts
Low flow and High
flow
Mobilize coarse
bed sediments
1, 2, 3, 4 High flow
pulse/Bankfull
Critical shear stress
to mobilize >50%
of bed material
Anytime
Maintain channel
form and key
habitats
1, 2, 3, 4 High flow
pulse/Bankfull
Morphologically
defined levels
Anytime
Source WET (2007)
Permission granted by WET project subject to proper citation