Difference between revisions of "Drainage time"

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[[File:Thunder Bay and Toronto.png|thumb|Storm inter-event times for Thunder Bay and Toronto]]
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[[File:Interevent times.PNG|thumb|link=https://public.tableau.com/views/StormIntereventTimesOntario/Dashboard1?:embed=y&:display_count=yes&publish=yes|Darker teal locations have more frequent rainfall; darker yellow have the least frequent rainfall. This image links to a Tableau dashboard, where the interactive data may be viewed in more detail.]]
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The recommended drawdown times for all storage and infiltration facilities are based upon rainfall statistics and likelihood that the facility will have had time to regenerate storage capacity before the arrival of the next storm event.
 
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A summary analysis of 14 locations across Ontario found that storms were most frequent in Thunder Bay and least frequent in Toronto.<br>
 
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The bar graph shows that there is a ~50% chance of rainfall occurring again within 48 hours (Thunder Bay) to 72 hours (Toronto).  
 
  
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[[File:Interevent times.PNG|thumb|link=https://public.tableau.com/views/StormIntereventTimesOntario/Sheet1?:embed=y&:display_count=yes&publish=yes|Darker teal locations have more frequent rainfall; darker yellow have the least frequent rainfall. This image links to a Tableau page, where the data may be viewed in more detail.]]
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The recommended drawdown times for all storage and [[infiltration]] facilities ([[infiltration trenches|trenches]], [[infiltration chambers|chambers]], [[bioretention]] etc.) are based upon rainfall statistics and likelihood that the facility will have had time to regenerate storage capacity before the arrival of the next storm event.  
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The analysis was conducted using the recommended minimum inter-event time of 12 hours from the MOECC<ref>MOECC Rainfall analysis 2017 </ref>, and earlier rainfall probability distribution parameters from 1960's-1980's <ref>Adams, B. J., and Papa, F. (2000). Urban stormwater management planning with analytical probabilistic models. Wiley.</ref>.
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A summary analysis of 14 locations across Ontario found that storms were most frequent in Thunder Bay and least frequent in Toronto; there is a ~50% chance of rainfall occurring again within 48 hours (Thunder Bay) to 72 hours (Toronto).  
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It is not anticipated that recent incremental changes to our climate will have significantly impacted this broad window of recommended drawdown times.
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The analysis was conducted using the recommended minimum inter-event time of 12 hours from the MOECC<ref>Aquafor Beech, EarthFX. Runoff Volume Control Targets for Ontario Final Report. 2016:125. https://municipalclassea.ca/files/7_DRAFT_MOECC_LID%20SWM%20Manual.pdf Accessed September 11, 2017.</ref>, and earlier rainfall probability distribution parameters from 1960's-1980's <ref>Adams, B. J., and Papa, F. (2000). Urban stormwater management planning with analytical probabilistic models. Wiley.</ref>.
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It is not anticipated that recent incremental changes to our climate will have significantly impacted this broad window of recommended drainage times.
 
Locations considered included:
 
Locations considered included:
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<div style="column-count:3;-moz-column-count:3;-webkit-column-count:3">
 
*Brantford
 
*Brantford
 
*Etobicoke
 
*Etobicoke
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*Trenton
 
*Trenton
 
*Windsor
 
*Windsor
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</div>
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==Calculating infiltration practice drainage time==
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Try the Darcy drainage time calculator tool for estimating the time required to fully drain the water storage reservoir of the facility assuming either one or three-dimensional drainage: <br>
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{{Clickable button|[[Media:Darcy drainage_20200528_locked.xlsx|Download the Darcy drainage time calculator tool]]}}
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==See also==
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[[Understanding rainfall statistics]]
  
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<references/>
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----
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[[Category:Infiltration]]
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[[Category: Background]]

Latest revision as of 14:43, 12 April 2024

Darker teal locations have more frequent rainfall; darker yellow have the least frequent rainfall. This image links to a Tableau dashboard, where the interactive data may be viewed in more detail.

The recommended drawdown times for all storage and infiltration facilities (trenches, chambers, bioretention etc.) are based upon rainfall statistics and likelihood that the facility will have had time to regenerate storage capacity before the arrival of the next storm event. A summary analysis of 14 locations across Ontario found that storms were most frequent in Thunder Bay and least frequent in Toronto; there is a ~50% chance of rainfall occurring again within 48 hours (Thunder Bay) to 72 hours (Toronto).

The analysis was conducted using the recommended minimum inter-event time of 12 hours from the MOECC[1], and earlier rainfall probability distribution parameters from 1960's-1980's [2]. It is not anticipated that recent incremental changes to our climate will have significantly impacted this broad window of recommended drainage times. Locations considered included:

  • Brantford
  • Etobicoke
  • Hamilton
  • Kingston
  • London
  • Niagara Falls
  • Oshawa
  • Ottawa
  • Peterborough
  • Sault Ste Marie
  • Thunder Bay
  • Toronto
  • Trenton
  • Windsor

Calculating infiltration practice drainage time[edit]

Try the Darcy drainage time calculator tool for estimating the time required to fully drain the water storage reservoir of the facility assuming either one or three-dimensional drainage:
Download the Darcy drainage time calculator tool

See also[edit]

Understanding rainfall statistics

  1. ↑ Aquafor Beech, EarthFX. Runoff Volume Control Targets for Ontario Final Report. 2016:125. https://municipalclassea.ca/files/7_DRAFT_MOECC_LID%20SWM%20Manual.pdf Accessed September 11, 2017.
  2. ↑ Adams, B. J., and Papa, F. (2000). Urban stormwater management planning with analytical probabilistic models. Wiley.

The period between the maximum water level and the minimum level (dry weather or antecedent level).

An underlying bed filled with aggregate or other void-forming fill material that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe.

Natural or artificial means of intercepting and removing surface or subsurface water (usually by gravity).

The portion of water precipitated onto a catchment area, which then flows as surface discharge from the catchment area past a specified point.

Water from rain, snow melt, or irrigation that flows over the land surface.

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