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Line 1: − 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}} − [[File:Dry enhanced swale.png|thumb|]] − [[File:Wet swale.png|thumb|]] − ==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 − − ===Check dams=== − {{:Check dams}} − − − − − 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. − |}} − − ===Modeling=== − {{:Swales: TTT}} − − ===Materials=== − {{:Turf: Roughness}} − {{:Turf: List}}
Redirected page to Enhanced swales
#REDIRECT [[Enhanced swales]]