View source for Infiltration: Sizing and modeling

==To calculate the required storage reservoir footprint area where the depth is fixed or constrained (1D drainage)==
To ensure that the water storage capacity of the facility is available at the onset of a storm event, it is recommended to size the storage reservoir despth, d<sub>r</sub>, based on the depth of water that will drain via infiltration between storm events. So d<sub>r</sub> can be calculated as:<br>
<math>d_{r} = \frac{f'\times t}{n} </math>
Where <br>
''f''' = [[design infiltration rate]] of the native soil (m/h) <br>
''t'' = [[drainage time]], based on local criteria or long-term average inter-event period for the location (e.g. 72 hr in southern Ontario).<br>
''n'' = Porosity of the stone bed aggregate material (typically 0.4 for 50 mm dia. [[reservoir aggregate|clear stone]])
<br>
In many locations there may be a limited depth of soil available above the seasonally high water table or top of bedrock elevation into which stormwater may be infiltrated.  In such cases the required storage needs to be distributed more widely across the landscape. <br>
Where the storage reservoir depth is fixed or constrained the footprint area of the water storage reservoir, A<sub>r</sub> can be calculated:
<math>A_{r}=\frac{i \times D \times Ai}{(n\times d_{r})+f'D}</math>