Which land-use change typically increases runoff volume and pollutant loading?

Which land-use change typically increases runoff volume and pollutant loading?

• A. Urban Expansion
• B. Reforestation
• C. Conservation Tillage
• D. Permeable Pavement

Answer: (A)

When land is converted to built, impervious surfaces, runoff tends to rise and carry more pollutants. Urban expansion adds roofs, roads, and parking lots that prevent water from soaking into the soil, so rainfall becomes larger and faster surface runoff. That runoff picks up oils, metals, nutrients, sediments, and other urban pollutants as it flows to streams, increasing both the volume of water and the amount of pollutants delivered to waterways. In contrast, reforestation increases interception of rainfall and promotes infiltration and natural filtration by soil and roots, which reduces runoff and pollutant transport. Conservation tillage preserves soil structure and residue, which also helps water infiltrate and reduces erosion. Permeable pavement is designed to allow water to infiltrate through the surface, lowering both runoff and pollutant loading compared with traditional impervious surfaces.

When land is converted to built, impervious surfaces, runoff tends to rise and carry more pollutants. Urban expansion adds roofs, roads, and parking lots that prevent water from soaking into the soil, so rainfall becomes larger and faster surface runoff. That runoff picks up oils, metals, nutrients, sediments, and other urban pollutants as it flows to streams, increasing both the volume of water and the amount of pollutants delivered to waterways.

In contrast, reforestation increases interception of rainfall and promotes infiltration and natural filtration by soil and roots, which reduces runoff and pollutant transport. Conservation tillage preserves soil structure and residue, which also helps water infiltrate and reduces erosion. Permeable pavement is designed to allow water to infiltrate through the surface, lowering both runoff and pollutant loading compared with traditional impervious surfaces.