Calculate the paved area entry time based on the length, slope and manning factor.
|
Option
|
Description |
|
Length |
The distance from the catchpit to the furthest hydraulic point of the paved area in metres. |
|
Slope |
The slope from the furthest hydraulic point expressed as a percentage. |
|
Manning Factor |
Specify the Manning factor for the paved area. Typical values are shown below. |
Woolhiser recommended the following Manning's coefficients for overland flow.
|
Surface
|
Range |
|
Concrete or asphalt |
0.010 - 0.013 |
|
Bare sand |
0.010 - 0.016 |
|
Gravelled surface |
0.012 - 0.030 |
|
Bare clay - loam soil (eroded) |
0.012 - 0.033 |
|
Sparse vegetation |
0.053 - 0.130 |
|
Veld |
0.100 - 0.200 |
|
Lawns |
0.170 - 0.480 |
The calculator updates the grass entry time control when you click OK.