Hydrology & Watershed Management Flashcards
7 cards from real CSM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hydrology & Watershed Management flashcards as text
Which hydrologic process describes the movement of water from the soil surface into the soil profile?
Answer: Infiltration
Infiltration is the process by which water on the ground surface enters the soil, while percolation refers to downward movement through the saturated zone.
A watershed with a curve number (CN) of 90 compared to one with CN of 60 will produce:
Answer: More runoff for the same rainfall event
Higher curve numbers indicate less permeable, more developed or compacted land, resulting in greater direct runoff for the same precipitation event.
What is the term for the portion of precipitation that eventually reaches a stream channel through shallow subsurface flow?
Answer: Interflow
Interflow (also called subsurface stormflow or throughflow) moves laterally through the upper soil horizons and contributes to streamflow during and shortly after storms.
The rational method formula Q = CiA requires that the storm duration equal the time of concentration because:
Answer: The entire watershed contributes runoff simultaneously at peak flow
When storm duration equals time of concentration, all parts of the watershed are contributing simultaneously, producing the maximum peak discharge for that rainfall intensity.
Which factor most directly reduces the lag time between precipitation and peak streamflow in an urbanized watershed?
Answer: Increased impervious cover and storm sewer networks
Impervious surfaces and storm sewers speed overland and channel flow, shortening the time for water to travel from the watershed to the outlet.
In the SCS/NRCS runoff curve number method, which antecedent moisture condition (AMC) applies to soils that are close to their wilting point?
Answer: AMC I (dry)
AMC I represents dry antecedent soil moisture conditions near wilting point, which produces the least runoff for a given rainfall event.
A stage-discharge relationship (rating curve) for a stream gauging station is developed by:
Answer: Correlating measured water surface elevations with measured streamflow discharges
Rating curves are developed empirically by repeatedly measuring both stage (water surface elevation) and discharge at a station over a range of flow conditions.