Calculates the rate of rainwater runoff and lists appropriate Surface Water Channel solutions for that specific surface water drainage application.
Changing the shape or size of a channel/system can have a marked effect on the velocity of the water and how much is moved.
To estimate surface water run-off there are a number of factors that need to be considered:
- Area of land to be serviced
- Surface type, (impervious or pervious)
- Type of terrain (flat, hilly or gently rolling).
Channel Capacity Calculator Disclaimer:
No warranty of any kind is expressed or implied and no liability will be accepted by Marley New Zealand Limited for any costs arising directly or indirectly as a result or consequences of the use of this calculator.
Any queries or suggestions concerning this calculator and the information generated by it should be emailed to info@marley.co.nz
Calculator is based on a rainfall Intensity of 100mm/hr (10 year storm)
| Recommended Channel | Channel Shape | Flow Rate l/s |
|---|---|---|
| Connecto Trade® 130 | U Shape | 8 L/s |
| Connecto Trade® 80 | U Shape | 4.5 L/s |
| Connecto™ Slim | Rectangular | 3.3 L/s |
| Connecto™ Medio | Rectangular | 8 L/s |
| Connecto™ Max | Rectangular | 17.6 L/s |
Run off Coefficients for the Rational Method
| Flat | Rolling | Hilly | |
| Pavement & Roofs | 0.90 | 0.90 | 0.90 |
| Earth Shoulders | 0.50 | 0.50 | 0.50 |
| Drives & Walks | 0.75 | 0.80 | 0.85 |
| Gravel Pavement | 0.85 | 0.85 | 0.85 |
| City Business Areas | 0.80 | 0.85 | 0.85 |
| Apartment Dwelling Areas | 0.50 | 0.60 | 0.70 |
| Light Residential: 1 to 3 units/acre | 0.35 | 0.40 | 0.45 |
| Normal Residential: 3 to 6 units/acre | 0.50 | 0.55 | 0.60 |
| Dense Residential: 6 to 15 units/acre | 0.70 | 0.75 | 0.80 |
| Lawns | 0.17 | 0.22 | 0.35 |
| Grass Shoulders | 0.25 | 0.25 | 0.25 |
| Side Slopes, Earth | 0.60 | 0.60 | 0.60 |
| Side Slopes, Turf | 0.30 | 0.30 | 0.30 |
| Median Areas, Turf | 0.25 | 0.30 | 0.30 |
| Cultivated Land, Clay & Loam | 0.50 | 0.55 | 0.60 |
| Cultivated Land, Sand & Gravel | 0.20 | 0.30 | 0.35 |
| Industrial Areas, Light | 0.50 | 0.70 | 0.80 |
| Industrial Areas, Heavy | 0.60 | 0.80 | 0.90 |
| Parks & Cemeteries | 0.10 | 0.15 | 0.25 |
| Playgrounds | 0.20 | 0.25 | 0.30 |
| Woodland & Forests | 0.10 | 0.15 | 0.20 |
| Meadows & Pasture Land | 0.25 | 0.30 | 0.35 |
| Unimproved Areas | 0.10 | 0.20 | 0.30 |
Note: Impervious surfaces in bold
Rolling = ground slope 2 – 10%
Hilly = ground slope greater than 10%
