As the implications of climate change become more apparent, we need to find innovative alternates to create sustainable cities. One such alternative is the use of decomposed granite in pathways and open areas.
Urban Heat Island (UHI) Effect
Asphalt and concrete, while widely used by landscape architects, intensifies the urban heat island (UHI) effect. The presence of concrete and asphalt in modern cities contributes to the urban heat island effect. Asphalt and concrete react to the warm weather by absorbing and holding the energy from the sun during the day and releasing it when it is cooler at night. At least 50% of urban hardscapes use concrete and asphalt while some regions in the mid-west use up to 94% of these materials.
Understanding this effect, and its implications, and finding alternatives to alleviate this problem is becoming more important all the time. For urban areas, use of decomposed granite for pathways, open areas and green roofs allows for surfaces which absorb less heat and contribute less to the UHI effect.
Asphalt and concrete are also impervious surfaces. In other words, they do not allow rainfall and water from urban usage to pass through to the groundwater table. Instead, water runs along these surfaces, picking up pollution and contaminants, including high amounts of inorganic nitrogen and phosphorus, along the way. These contaminants are then washed into storm drain systems and eventually back into rivers, lakes, and oceans.
Using decomposed granite rather than concrete or asphalt allows water to pass through. The porous texture of the decomposed granite allows absorption of water, allowing water to return more easily to the groundwater table, filtering out harmful pollution and contaminants are along the way.
As climate change continues, reactions to climate change in urban environments will continue to increase. Solutions that use innovative materials to mitigate harm is of the utmost importance. Using permeable decomposed granite surfaces with stabilizers such as Organic-Lock is one important way we can increase sustainability in urban areas.