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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-This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration. <br>
+#REDIRECT [[Enhanced swales]]
-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==
-<h3>Best cross sections</h3>
-[[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.
-===Check dams===
-{{:Check dams}}
-==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
-{|class="wikitable"
-|+ Slope variations
-|-
-|< 2 %||Use underdrain to distribute water for infiltration
-|-
-|2 - 5 %||Design swale for surface flow, consider check dams
-|-
-||5 %||Check dams required to reduce effective slope to 2 – 3 %
-|}
-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.
-|}}
-<h3>Modeling</h3>
-{{:Swales: TTT}}
-<h3>Materials</h3>
-{{:Turf: List}}

Difference between revisions of "Enhanced grass swales"

Latest revision as of 14:23, 12 March 2018

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