The main goal of low-impact design strategies is to distribute or scatter stormwater and urban runoff across developed sites. Therefore, decreasing the adverse impact on water quality and to allowing for the replenishment of groundwater supplies through percolation. Although not all developers currently use LID strategies and practices, it is rapidly becoming the design approach required in many areas of the United States. LIDs basic principle is to model stormwater management after the measures which innately take place in the natural environment, finding and implementing methods to manage precipitation and its associated runoff at its source. This is made possible through a sequenced implementation of strategies to prevent runoff, lessen runoff, and remove pollutants from any runoff that does occur.
These strategies can be accomplished and met by taking steps to implement the following:
- preserving and conserving existing natural areas, i.e. only hardscape the areas that need to be covered with impermeable materials, allowing as much of the area to remain in as natural a state as possible
- minimizing the development’s impact on the area’s natural hydrology
- controlling the runoff rate; keeping the water onsite and at its source for as long as possible
- decentralizing and scattering LID strategies/practices across the development site, setting up methods or controls for infiltrating, storing, allowing evaporation, and/or detaining runoff as close to its original source as possible
- implementing pollution control and prevention as well as appropriate maintenance procedures
Benefits of Low-Impact Design for Stormwater Management
Many benefits can be derived from the implementation of LID strategies to prevent or lesson runoff and to also remove contaminants from it.
Improves the Environment
LID strategies improve the environment in the following ways:
- Quality vegetation and trees improve air quality by absorbing air pollutants, trapping airborne particulates and producing oxygen. Incorporating LID features, instead of implementing turf grass into the design, reduces the need for mowing. Thereby, reducing emissions of equipment needed to mow and trim turf grasses.
- By reducing the velocity and volume of runoff, flooding is reduced and often eliminated. Water allowed to flow through natural waterways and through LID features is better quality when it reaches its final destination.
- With the use of plenty of native vegetation in the LID feature, a natural habitat is preserved or implemented.
- A well-designed LID strategy can assist in relinking a fragmented ecosystem.
Improves Quality of Life and Public Health
LID strategies improve the quality of life and public health in the following ways:
- When attractive vegetation is used in the implementation of LID, property aesthetics are improved which can lead to increased property values.
- LID features such as vegetated medians, vegetated traffic islands and curb bump-outs at pedestrian crossings, decreases the distance pedestrians must travel in a traffic lane and slows traffic, thereby improving public safety.
- Noise pollution is reduced because vegetation buffers the sound.
- Sport and recreation courts can be paved with porous materials.
- People can engage with mother nature and outdoor activities in vegetated public rights-of-way, taking part in activities such as walking/hiking, birdwatching, gardening, etc.
Improves Climate Resiliency
According to the Center for Climate and Energy Solutions, climate resilience is “the ability to anticipate, prepare for, and respond to hazardous events, trends, or disturbances related to climate. Improving climate resilience involves assessing how climate change will create new, or alter current, climate-related risks, and taking steps to better cope with these risks.” LID strategies improve climate resiliency in the following ways:
- Through the provision of shade, the reduction of ambient temperatures, and the absorption of solar radiation, LID strategies that include vegetation and trees reduce the threat of excessive heat exposure impacts.
- Trees, larger vegetation and green roofs provide shade, decreasing the severity and incidence of heat-related illnesses and reduces energy use/costs.
- More carbon is trapped in soil and vegetation using LID strategies, helping to reduce greenhouse gas emissions.
- The capture of rainwater, using cisterns and rain barrels, may reduce the need for potable/recycled water, thereby decreasing water treatment costs.
- Using native and locally adapted plants as dictated by LID strategies results in less need for irrigation, reducing the need for potable/recycled water, also decreasing water treatment costs.