The Hydrological (Water) Cycle And Drainage Basin Systems Practice Test

Understanding how the moisture already present in the soil before rainfall influences the hydrologic response. The term for that pre-existing moisture state is antecedent soil moisture. It matters because the soil’s ability to absorb new rainfall depends on how wet it is at the start. If the soil is dry, infiltration is higher, so more water soaks in and less runs off. If the soil is already moist or near saturation, infiltration slows and a larger portion of rainfall becomes surface runoff. This concept helps explain why the same rainfall can produce different runoff amounts depending on prior soil moisture. Other terms don’t describe the soil’s moisture state before rain: clouds relate to atmospheric moisture, sheetwash is a runoff process, and a watershed is the drainage basin as a whole.