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−#REDIRECT[[Enhanced grass swales]]+
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[[File:Dry enhanced swale.png|thumb|Skeleton schematic illustrating the installation of [[check dams]] with centralized, flow concentrating cutouts]]
+[[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| 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.
+|}}
+{{:Turf}}
+===Check dams===
+{{:Check dams}}
+===Modeling===
+{{:Swales: TTT}}