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Line 16: − + − {|class="wikitable"+ − |+ Examples worked without units, using the ratios given+ − |- + − !Section − !Wetted perimeter − !Area − } − +
→Planning considerations
<h3>Best X-section</h3>
<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]]
[[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.
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===