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Redirected page to Enhanced swales
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−This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration. <br>+For underground conveyance which promotes infiltration, see [[Exfiltration trenches]].<br>
−For conveyance along planted channels, on both surface and underground, see [[Bioswales]].
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−==Overview==
−'''The fundamental components of an enhanced grassed swale are:'''
−*Graded channel
−*[[Turf: List| Resilient turf grass]]
−*[[Check dams]], to facilitate short term ponding
−'''Additional components may include:'''
−*[[Absorbent landscapes| Amended soil]], to increase infiltration to soils below
−*[[Liner|Impermeable membrane]], to prevent infiltration to soils below
−*[[Turf reinforcement]], to prevent scour
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−==Planning considerations==
−===Best cross sections===
−[[File:Best X-section.png|thumb|Both sections a)triangular and, b)trapezoidal, are constrained within ratios of 8:1 H:V]]
−[[File:Sections_perimeters.png|thumb|At lowest flow rates (smallest area) the trapezoidal swale (b) has the greater wetted perimeter; at higher flow rates (greater area) the triangular geometry (a)has a larger wetted perimeter for same area. Both channels modelled using ratios shown in figure above]]
−For a given width and depth, the difference between a triangular and trapzoidal section is small. As shown in the diagrams, under low flow conditions the trapezoidal has greater wetted perimeter, and at higher flows the triangular profile does.
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−==Design==
−All swales should be designed to meet the following criteria:
−*Minimum residence time of 5 minutes.
−*Maximum flow velocity 0.3 m/s
−*Bottom width between 0.6 - 2.4 m
−*Minimum length 30 m
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−===Adding check dams===
−To calculate the spacing and sizing of check dams, see [[Check dams: Sizing]]
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−Maximum depth of flow
−{{plainlist|
−*50% height of grass for regularly mown swales, to maximum of 75 mm.
−*33% height of vegetation for infrequently mown swales.
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−<h3>Modeling</h3>
−{{:Swales: TTT}}
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−<h3>Materials</h3>
−{{:Turf: List}}
#REDIRECT [[Enhanced swales]]
−Enhanced swales aim to both reduce the flow rate and retain a portion of the conveyed water. For these purposes the best x-section is that which maximizes the wetted perimeter for a given area.
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