What direct impact do concrete buildings constructed after clearing forests for urbanization have on surface runoff?

Correct answer: The speed and volume of surface runoff increase greatly

Correct answer: B. Natural forests contain vegetation, litter and porous soil. These features slow rainwater, encourage infiltration and temporarily store part of the rainfall. When forests are cleared and the ground is covered by concrete, the surface becomes largely impervious. Water cannot easily enter the soil, so a greater fraction moves over the surface. Drains and sloping paved surfaces can also convey this water rapidly, increasing runoff volume and often its speed. A is wrong because concrete does not stop runoff; it generally promotes it. C is wrong because reduced infiltration tends to reduce groundwater recharge rather than greatly raise groundwater levels. D is wrong because rainfall remains in the environment as runoff, evaporation or infiltrated water. Memory cue: less vegetation plus more impervious surface means more rapid runoff and greater flood risk.