CFM Hydrology & Hydraulics Flashcards
6 cards from real CFM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CFM Hydrology & Hydraulics flashcards as text
A watershed with impervious surfaces increased from 10% to 40% will generally experience what change in peak runoff?
Answer: Peak runoff increases due to reduced infiltration and faster response time
Increased impervious cover reduces infiltration and shortens time of concentration, resulting in higher and faster peak runoff from the same storm event.
What is the primary purpose of a 'No-Rise Certification' in floodway encroachment analysis?
Answer: To demonstrate that proposed development will not increase the BFE in the floodway
A No-Rise Certification, sealed by a licensed engineer, verifies that proposed floodway encroachment will not cause any increase in BFE based on hydraulic modeling.
Which of the following best describes 'effective hydraulic connectivity' in floodplain management?
Answer: The ability of floodwaters to move freely across the floodplain without obstruction
Effective hydraulic connectivity refers to the unobstructed movement of floodwaters across the floodplain, which is critical for maintaining conveyance and reducing upstream flood levels.
In a Detailed Flood Insurance Study, cross-section data is used in hydraulic modeling to determine:
Answer: Water surface elevations at specific locations along a stream
Cross-sections represent channel and floodplain geometry at selected locations, enabling HEC-RAS or similar models to compute water surface elevations for the base flood discharge.
What does a Flood Insurance Rate Map (FIRM) show that an older Flood Hazard Boundary Map (FHBM) did not?
Answer: Base Flood Elevations and insurance risk zones
FIRMs include Base Flood Elevations and detailed flood insurance risk zones derived from engineering studies, providing quantitative data that FHBMs lacked.
The 'regulatory floodway fringe' (flood fringe) is defined as:
Answer: The portion of the 100-year floodplain outside the floodway that can accommodate limited development
The flood fringe is the area of the 100-year floodplain outside the designated floodway; it can be developed if structures are elevated to or above BFE.