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The Runoff Dilemma: The Environmental Impact of Impervious Surfaces

Andrew Hwang and Joshua Yoo

    From the bustling city streets to seemingly harmless parking lots, impervious surfaces, like concrete, asphalt, and rooftops - are ever present features of our urban landscapes. These surfaces are areas where water is not permeable to the ground; that is, surfaces that prevent groundwater from being absorbed by soil. Not to mention, with urban development, the area covered by impervious surfaces only increases. While they may serve our infrastructural needs, they also unwittingly contribute to a significant environmental challenge: water runoff.

   Water pollution is one of the primary issues associated with runoff from impervious surfaces. As rainwater moves across these hard surfaces, it collects various pollutants such as oil, grease, chemicals, and metals, which inevitably end up in water bodies. The increased concentration of pollutants in our water systems has detrimental effects on the health of aquatic life and the quality of drinking water.

   The impermeability of these surfaces also exacerbates the risks associated with flooding. Natural landscapes allow rainwater to percolate into the ground, replenishing groundwater resources. However, with impervious surfaces, rainwater has nowhere to go but directly into storm drains, significantly increasing surface water volume in a short period. This can overwhelm drainage systems, leading to urban flooding and associated property damage. 

   Impervious surfaces also contribute to the 'urban heat island' effect, where urban and suburban areas are significantly warmer than rural ones. This is primarily due to the heat absorbed and radiated by concrete and asphalt surfaces, leading to increased energy consumption for summer cooling and contributing to global warming. 

   Moreover, runoff from impervious surfaces disrupts the natural water cycle. In a healthy ecosystem, precipitation infiltrates the soil, replenishing groundwater and contributing to the moisture available to plants and trees. This infiltration also naturally filters the water, removing pollutants. Impervious surfaces interrupt this cycle by preventing absorption of water into soil, leading to reduced groundwater recharge and exacerbating the impacts of drought. As we grapple with the environmental issues caused by impervious surfaces, it's clear that innovative, sustainable urban planning solutions are needed. Practices such as using permeable pavements, green roofs, rain gardens, and other green infrastructure techniques can help mitigate the adverse effects of impervious surfaces. These methods help absorb and cleanse stormwater at its source, cool urban areas, promote biodiversity, and enhance urban aesthetics. 

   In conclusion, while impervious surfaces are integral to our urban infrastructure, their environmental consequences cannot be overlooked. As urbanization continues to increase, proactive measures to reduce runoff and promote more sustainable, water-wise communities are not just beneficial but absolutely necessary for our collective future.

"Progress is impossible without change, and those who cannot change their minds cannot change anything. "

- George Bernard Shaw

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