How do paved and cemented urban surfaces generally affect hydrological lag time?

Correct answer: The time decreases greatly

Correct answer: B, hydrological lag time decreases greatly. Hydrological lag time is the interval between the period of maximum rainfall and the peak discharge, or between rainfall and the strongest stream response, depending on the definition being used. Vegetated and permeable ground allows infiltration and temporary storage, which delays runoff. Concrete, asphalt, and other paved surfaces are relatively impermeable, so much less rain enters the soil. Water moves rapidly as surface runoff into drains and channels, causing a quicker and often sharper rise in discharge; therefore, the lag time is shortened. A is incorrect because increasing impermeable cover normally removes storage and delay rather than adding it. C is incorrect because land cover changes the response time. D is too absolute: runoff is faster, but it is not literally instantaneous in every storm or always zero lag. Other factors, including slope, drainage design, rainfall intensity, and basin size, also matter. Memory cue: pavement means less infiltration, faster runoff, shorter lag, and potentially greater flood peaks.