New green solutions to stormwater management

So far in this course activity, we have looked at challenges associated with pipe-based drainage systems and the problems with stormwater pollution. In recent decades, there has been increasing attention for more natural and green solutions that can mitigate these issues.

Some different names you may see for these new practices are Sustainable Urban Drainage Systems (SUDS), Water Sensitive Urban Design (WSUD), Stormwater Control Measures (SCM), Low Impact Development (LID), Nature Based Solutions (NBS), or green infrastructure.

The idea behind these greener solutions is that, instead of simply removing stormwater quickly, they try to:

• Infiltrate stormwater into the soil.
• Retain the stormwater in place.
• Detain stormwater so it runs of more slowly.

These goals are achieved by using a combination of two main approaches:

• Slowing down surface runoff by letting water flow over vegetated areas.
• Letting stormwater move vertically through soil or soil-like media, either infiltrating stormwater towards groundwater or slowing it down before it reaches a pipe network.
• Using ponds and other storage volumes to temporarily store water, usually on the surface.

Besides reducing and delaying runoff, these methods can also have beneficial effects on stormwater quality. Stormwater can contain many pollutants. Letting water flow through soil or soil-like media allows some pollutants to be filtered from the water, while letting water stand in ponds for some time allows some pollutants to settle to the bottom. This way the pollutants end up in stormwater control measures rather than the natural environment. Vegetation can also contribute to the removal of pollutants from water, as can certain biological processes.