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 soil hydrologic group has the highest runoff potential and lowest infiltration rate when thoroughly wet?
Answer: Group D
Hydrologic Soil Group D consists of soils with very slow infiltration rates (clay soils or soils with a high water table) and produces the highest runoff.
The concept of 'bankfull discharge' is significant in watershed management because it:
Answer: Is the flow that does the most geomorphic work and shapes the channel
Bankfull discharge, typically corresponding to the 1.5- to 2-year return interval, is responsible for transporting the most sediment and maintaining channel form over time.
What is the primary purpose of a unit hydrograph in stormwater hydrology?
Answer: To relate a unit depth of excess rainfall to a direct runoff hydrograph for a watershed
A unit hydrograph represents the direct runoff response of a watershed to one unit (1 inch or 1 cm) of excess rainfall uniformly distributed over the watershed for a specified duration.
Which of the following best describes the 'baseflow recession' portion of a streamflow hydrograph?
Answer: The slow drainage of groundwater into the stream after storm runoff has ceased
Baseflow recession represents the gradual depletion of groundwater storage that sustains streamflow between storm events, typically following an exponential decay pattern.
A developer proposes to fill a wetland that provides 50 acre-feet of floodwater storage. Under the watershed management perspective, this action would most likely:
Answer: Increase downstream flood peaks by eliminating natural detention storage
Wetlands attenuate flood peaks by temporarily storing floodwater; eliminating this storage increases and accelerates downstream runoff, raising peak flows.
The dimensionless unit hydrograph developed by the NRCS is characterized by:
Answer: A recession limb that is longer than the rising limb
The NRCS dimensionless unit hydrograph has a skewed shape where the recession limb extends approximately 1.67 times longer than the rising limb, reflecting slower groundwater drainage.
In watershed delineation, a 'pour point' refers to:
Answer: The outlet or lowest point through which all watershed runoff exits
The pour point (or watershed outlet) is the single point at the lowest elevation through which all surface water within the delineated watershed drains.