What is the primary environmental consequence of urban expansion on stormwater?

What is the primary environmental consequence of urban expansion on stormwater?

• A. Increased Runoff and Pollutant Loading
• B. Decreased Runoff
• C. Increased Infiltration
• D. No Change in Runoff

Answer: (A)

Urban expansion introduces many impervious surfaces like roads, parking lots, and rooftops that prevent rain from soaking into the ground. With less infiltration, rainfall becomes surface runoff that arrives at streams more quickly and in greater amounts. This not only increases the total volume of water flowing through waterways but also carries pollutants—oil and metals from vehicles, sediments, nutrients from fertilizers, and litter—into rivers and lakes. So the primary environmental consequence is the combination of more runoff and higher pollutant loading into water bodies. Choices that talk about decreased runoff or increased infiltration don’t fit because the added impermeable surfaces block infiltration and boost runoff, and saying there’s no change ignores the hydrology shift urban development induces.

Urban expansion introduces many impervious surfaces like roads, parking lots, and rooftops that prevent rain from soaking into the ground. With less infiltration, rainfall becomes surface runoff that arrives at streams more quickly and in greater amounts. This not only increases the total volume of water flowing through waterways but also carries pollutants—oil and metals from vehicles, sediments, nutrients from fertilizers, and litter—into rivers and lakes. So the primary environmental consequence is the combination of more runoff and higher pollutant loading into water bodies. Choices that talk about decreased runoff or increased infiltration don’t fit because the added impermeable surfaces block infiltration and boost runoff, and saying there’s no change ignores the hydrology shift urban development induces.