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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}} − ==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 X-section</h3> − [[File:Best X-section.png|thumb|Both sections a)triangular and, b)trapezoidal, are constrained within ratios of 8:1 H:V]] − 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. The trapzoidal channel has the marginally greater hydraulic radius, but also the greater area. − − * Triangle (a), wetted perimeter at full bank depth = 8.25 (unitless) − * Trapezoidal (b), wetted perimeter at full bank depth = 8.32 (unitless) − − Where the X-section areas are set equal (to demonstrate equivalent flow), the depth of water in the example trapzoidal channel is 4/5 that of the triangular. − − ===Check dams=== − {{:Check dams}} − − ==Design== − 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>
Redirected page to Enhanced swales
#REDIRECT [[Enhanced swales]]