Difference between revisions of "Enhanced grass swales"

Latest revision as of 14:23, 12 March 2018

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Enhanced swales

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-[[File:Dry enhanced swale.png|thumb|Skeleton schematic illustrating the installation of [[check dams]] with centralized, flow concentrating cutouts]]
+#REDIRECT [[Enhanced swales]]
-[[File:Wet swale.png|thumb|The check dams are spaced slightly further apart than would be recommended to maximize infiltration capacity i.e. ponding isn't quite continuous between the dams.]]
-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]].
-{{TOClimit|2}}
-==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
-==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]]
-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.
-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.
-==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
-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.
-|}}
-===Check dams===
-{{:Check dams}}
-===Modeling===
-{{:Swales: TTT}}
-===Materials===
-{{:Turf: Roughness}}
-{{:Turf: List}}

Difference between revisions of "Enhanced grass swales"

Latest revision as of 14:23, 12 March 2018

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