LID Urban Stormwater Management Options

Low Impact Development stormwater management options that your local municipal councilors should be aware of.

Climate change is felt through extreme weather occurrences such as prolonged droughts, heatwaves and wildfires often followed by intense bursts of precipitation causing flooding and mudslides. Urban centers in large part experience their own extreme weather as well as contribute to it by draining rainwater from their area and dehydrating the landscape. This causes drastic shifts in spatial and temporal precipitation patterns affecting precipitation not only above an urban center but in the surrounding country side as well. Draining rainwater from an urban center results in what is commonly referred to as the heat island effect. The negative effects of rainwater run-off on the climate can easily be mitigated by retaining rainwater within the vicinity where it falls through creative urban green architecture. These methods of rainwater management have come to be known as low impact development stormwater practices, also referred to as LID.

You can contact your local municipal councilors or municipal organization that addresses urban planning and climate change resiliency and let them know that there is more to be done than just reducing carbon emissions within cities. Creative stormwater management solutions promote a healthier urban setting and they also sustain the local economy through job creation and business opportunities.

Swales, Constructed Wetlands, Retention Ponds, Rain Gardens, Green Roofs & Facades, Permeable Paving, etc.

There are numerous stormwater management features that can be implemented by your local municipality which greatly enhance the resiliency of the urban landscape and mitigate the majority of weather extremes mentioned above.

Bio-swales

In urban areas, bio-swales or retention swales serve the purpose of slowing down stormwater run-off and filtering the water before it enters the water basin. They are designed to keep stormwater as long as possible within the swale in order to prolong peak flow and thus reduce the risk of flooding by minimizing stress placed on the conventional sewage system. Swales are a depressed drainage course with gently sloping sides filled with vegetation and other organic matter. Similar to other nature-based stormwater management systems, bio-swales play a key role in smart urban design by providing a host of benefits. Hence, their implementation around parking lots and roads where numerous pollutants from cars can enter the water stream are filtered by bio-swales.

Benefits:

  • Extended biological treatment
  • Improves air quality
  • Promotes evapotranspiration
  • Prolongs peak run-off
  • Aesthetic appeal
  • Controls sedimentation

 

Constructed Wetlands

Constructed wetlands are a prime example of nature-based solutions that provide a host of benefits. Constructed wetlands are designed systems that mimic wetlands found in natural ecosystems. They are characterized by permanent standing water and abundant biodiversity in the form of vegetation, organisms and wildlife. Stormwater retention can be effectively managed by constructed wetlands as well as greywater purification before release into the water basin. Constructed wetlands can be implemented in city parks and forests as well as used for land reclamation after mining or agriculture has ceased. They are also a great feature for recreational resort towns where space is not as difficult to come by as it is in larger urban centers. Constructed wetlands play a vital role in cleaning contaminated water by removing heavy metals, solids, organic matter, pathogens and nutrients. The combination of vegetation, micro-organisms and soil and gravel substrate act as nature’s filters.

Benefits:

  • Biodiversity provides extra chemical and biological filtration of stormwater
  • Promotes evapotranspiration
  • Sedimentation control
  • Peak flow reduction
  • Habitat for migratory birds and other wildlife
  • Effective feature of land reclamation

 

Rain Gardens

Rain gardens are not only a rainwater retention feature for a home but are a functional feature of public urban landscapes. Rain gardens are depressions in the landscape containing diverse plant life that capture rainwater run-off from streets and buildings instead of it being drained via a sewage system. Rain gardens reduce stormwater run-off and enable infiltration and evapotranspiration which contributes to the replenishment of groundwater sources and maintains a stable micro-climate. Rain gardens also filter contaminated water before it makes its way into the local water basin. They stop suspended solids from entering stream and instead build up as sedimentation as well as filter contaminated water through extended biological treatment.

Benefits:

  • Reduce peak flow rate
  • Contribute to aesthetically pleasing green urban architecture
  • Promote infiltration and evapotranspiration contributing to improved micro-climate
  • Water filtration
  • Sedimentation control
  • Promotes biodiversity
  • Improve air quality

 

Green Roofs

Green roofs in their basic meaning are roofs covered with special vegetation. There are two types of green roofs, extensive and intensive green roofs. Extensive green roofs have limited soil depth and plant diversity; they are meant to provide insulation to the building, absorb solar radiation and retain rainwater as well as add aesthetic appeal. Whereas intensive green roofs contain rich biodiversity and much deeper substrate and are often used as functional zones for relaxation and can even include vegetable crops.

Green roofs expand the vegetative cover of a property and therefore contribute to a more stable micro-climate. They make use of dead space by adding function to a roof in the form of recreational space. Green roofs can be easily incorporated into green urban architecture as they are non-encroaching onto valuable urban commercial, retail, residential, industrial or any other functional space. In urban areas, green roofs act as insulation reducing temperature fluctuations reducing heating costs in the winter and cooling costs in the summer. They reduce the peak flow rate by retain water thus mitigating risks of flooding.

Benefits:

  • Reduce the heat island effect
  •  Stormwater management
  •  Improved water quality
  •  Improved air quality
  •  Carbon sequestration
  •  Increased biodiversity
  •  Habitat & sustenance for urban bird life and other organisms
  •  Reduce ambient noise

 

 

 

 

 

 

Green Facades

Green facades also commonly referred to as vertical gardens consist of vegetative cover on the exterior or interior walls of buildings or other urban structures such as highway pillars. A common approach to green façade installation consists of specially constructed modular panels containing substrate and vegetation that are mounted on walls providing many benefits in addition to its aesthetic appeal. Modern ecological green facades rely on rainwater for irrigation instead of conventional irrigation methods. Like green roofs, green facades increase green space in an urban area without encroaching onto functional space. Green facades usually do not require any additional structural adjustments to the building or structure. The modular panels are pre-fabricated and attach directly to a concrete wall.

Benefits of green facades:

  • Aesthetically pleasing
  • Increase green space of an urban center without encroaching onto functional space
  • Improved air quality
  • Carbon sequestration
  • Increased bio-diversity
  • Reduce ambient noise
  • Increased thermal insulation
  • Rainwater retention

 

Reinforced Permeable Surfaces

Permeable surfaces or pervious surfaces allow water to infiltrate vertically into the ground as well as promote evapotranspiration. Permeable paving comes in many forms and shapes and often includes vegetative cover. There are multiple products on the market that can be used to cover the earth’s surface without sealing it thus promoting low impact development. Parking lots, reinforced river banks, home drive ways, pedestrian zones and other areas requiring solid footing can be developed with permeable paving solutions. Permeable paving increases functional space because it reduces the need for the construction of conventional drainage systems.

The open cell concrete block is a basic example of permeable paving. Popular with driveways in residential areas, the open cell concrete block and other similar solutions available on the market are an effective measure for LID stormwater management that can be incorporated into urban landscapes.

Benefits:

  • Promotes infiltration and evapotranspiration
  • Reduce peak flow rate
  • Reduce heat island effect as it decreases the amount of sealed concrete and asphalt cover in urban areas
  • Aesthetically pleasing
  • Reduces need for conventional stormwater drainage systems
  • Customizable depending on requirements

 

There are numerous other great options for LID stormwater management being designed around the world. Encourage your local councilors and representatives to act and protect rainwater as it is the fastest way to improving the micro-climate of your city.

If you have suggestions of your own or would like to see more features, please email us at info@rainforclimate.com.