HY8:Stilling Basins: Difference between revisions

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* [[HY8:USBR Type III Stilling Basin|USBR Type III Stilling Basin]]
* [[HY8:USBR Type III Stilling Basin|USBR Type III Stilling Basin]]
* [[HY-8:USBR Type IV Stilling Basin|USBR Type IV Stilling Basin]]
* [[HY8:USBR Type IV Stilling Basin|USBR Type IV Stilling Basin]]
* [[HY-8:Saint Anthony Falls (SAF Stilling Basin)|St. Anthony Falls (SAF) Stilling Basin]]
* [[HY8:Saint Anthony Falls (SAF Stilling Basin)|St. Anthony Falls (SAF) Stilling Basin]]
 


The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value.  If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions.  Stilling Basins resemble the following illustration.
The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value.  If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions.  Stilling Basins resemble the following illustration.
                        
                        
[[Image:HY8image7.jpg]]
:[[Image:HY8-StillingBasin.jpg|500 px]]
 


Variables from the figure
Variables from the figure
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* L<sub>S</sub> &mdash; Length of the basin from the bottom of the basin to the basin exit (sill)
* L<sub>S</sub> &mdash; Length of the basin from the bottom of the basin to the basin exit (sill)
* T<sub>w</sub> &mdash; Tailwater depth leaving the basin
* T<sub>w</sub> &mdash; Tailwater depth leaving the basin


== Warning for Stilling Basin Width ==
== Warning for Stilling Basin Width ==

Latest revision as of 14:51, 2 November 2017

The four types of Stilling Basins External Energy Dissipators available in the program:

The maximum width of an efficient 'USBR' type stilling basin is limited by the width that a jet of water would flare naturally on the basin foreslope. The user is given the maximum flare value and is prompted to enter a basin width smaller than this value. If a 'SAF' basin is used, the basin width is set equal to the culvert width and the user is prompted to choose either a rectangular or flared basin depending on site conditions. Stilling Basins resemble the following illustration.

HY8-StillingBasin.jpg

Variables from the figure

  • W0 — width of the channel
  • WB — Width of the basin
  • y0 — Culvert outlet depth
  • y1 — Depth entering the basin
  • y2 — Conjugate depth
  • S0 — Slope of the channel
  • ST — Slope of the transition
  • SS — Slope leaving the basin
  • Z0 — ground elevation at the culvert outlet
  • Z1 — ground elevation at the basin entrance
  • Z2 — ground elevation at the basin exit
  • Z3 — Elevation of basin at basin exit (sill)
  • LT — Length of transition from culvert outlet to basin
  • L — Total basin length
  • LB — Length of the bottom of the basin
  • LS — Length of the basin from the bottom of the basin to the basin exit (sill)
  • Tw — Tailwater depth leaving the basin

Warning for Stilling Basin Width

Since the maximum basin width is a function of basin depth, the maximum width may decrease as the program increases the basin depth while converging on a solution. Therefore the maximum basin width may fall below the user's first choice for basin width. In this case, the user will be prompted for a new basin width.