Designing around drainage areas can be challenging. Drainage areas are any area where water naturally flows downhill and collects in a basin or catchment area.
Drainage areas can be small areas in a home landscape or they can be the size of a watershed that drains an entire region.
Drainage areas can also be sources of pollution and erosion especially when the flow becomes concentrated as in storm events.
Natural ravines and other topographic features as well as designed water catchment systems or large areas of paving are examples of drainage areas. Planting around these areas can help reduce water flow and stabilize banks, while improving water quality.
|
Drainage area |
Water collection areas |
| Ravines | Wetlands |
| Slopes | Ponds |
| Parking lots and other impervious surfaces | Streams and Rivers |
| Downspouts on buildings | Ocean |
| Compacted Soils | Topographic depressions |
| Non-vegetated soils | Designed detention and retention basins |
| Watersheds | Other water catchment and storage systems |
| Planting beds | |
| Rain gardens | |
| Swales and ditches | |
| Bioswales |
Planning and Design Considerations for Drainage Areas
Drainage areas are a great way to take advantage of “harvesting” and using excess seasonal water. Curb cuts are one way to allow stormwater from streets to be captured in designed depressions planted with native and other water wise plants that can take advantage of the excess seasonal water.
- Create depressions in planting beds to capture rainwater instead of mounds
- Keep as much existing vegetation as possible
- Re-vegetate slopes where needed
- Terrace slopes
- Where allowed, use curb cuts to create catchment basins in parking strips
- Use native adapted drought tolerant plants that can tolerate short periods of wet roots
Additional Resources:
Northeast
Maine – Adding a Rain Garden to your Landscape
Southeast
West
Oregon – Oregon Rain Garden Guide Available
Washington, Seattle Public Utilities Street Edge Alternatives