Script 2026/2027 | Exam Preparation Guide
| A+ Rated
• Base Flood -✓✓The 1% chance/year flood. The base or min. flood elevation standard
that communities must adopt in their local programs.
• Floodplain -✓✓Floodway + floodway fringe; area subject to 1% chance flood
• floodway -✓✓Channel of river and the adjacent area that must be reserved open
space; an engineering construct; provides for discharge of base flood
• flood fringe -✓✓the fringe or backwater areas of a flood that store nearly still water
during a flood and gradually release it downstream after the flood; development may be
allowed here
• 44 CFR -✓✓Parts 59, 60, 65, and 70 relate to the NFIP. "Emergency Management &
Assistance" Title 44 of the Code of Federal Regulations.
• alluvial fan (flooding) -✓✓A fan-shaped deposit of sediment formed when a stream's
slope is abruptly reduced (hence flow path of stream becomes unpredictable, resulting
in flooding **characterized by:** 1) high velocity flows; 2) active erosion and
sedimentation; 3) unpredictable flow paths
• FIS -✓✓Flood Insurance Study
• FHBM -✓✓Flood Hazard Boundary Map. An official map of a community published by
FEMA that delineates the approximate boundary of the floodplain. An FHBM is
generally the initial map provided the community and is eventually superceded by a
FIRM
• FBFM -✓✓Flood Boundary Floodway Map. An official map of a community, on which
FEMA has delineated the regulatory floodway. Recent FISs show the floodway on the
FIRM and do not include an FBFM.
• Levees -✓✓An embankment designed to manage a certain amount of floodwater and
can be overtopped or fail during flood events exceeding the level for which they were
designed; typically built parallel to a waterway to reduce the risk of flooding on the
landward side.
• Special Flood Hazards -✓✓Closed basin lakes, uncertain flow paths, dam breaks, ice
jams, and mudflows are the most common types found in the US.
, • Closed basin lakes -✓✓Two types: no outlets like Great Salt Lake, or irregular outlets
like the Great Lakes; either way == large fluctuations in water surface elevation & low
drainage rates. Septic fields are unusable. Waves may be experienced. A type of
special flood hazard.
• Uncertain flow paths -✓✓Ex: *alluvial fan* = a fan-shaped area at the base of a valley
where the slope of a mountain flattens out, the high-velocity floodwater decreases in
speed and spreads out like in a **sheet flow** dropping sediment and rock. May have
multiple, undefined channels. Common in mountainous areas with less ground cover
and more opportunity for erosion. *Poses 3 hazards: (1) velocity of water/debris, (2)
sedimentation, (3) migrating channels
Ex: *moveable stream bed* = when high velocity flood runs through an area with loose
sand or soil, the erosion and sedimentation can occur rapidly and cause channel
degradation, aggravation, and/or migration.
• Channel degradation -✓✓When a channel is lowered/flattened. Caused by erosion
and sedimentation.
• Channel aggradation -✓✓When a channel is filled in
• Channel migration -✓✓When a channel moves due to erosion, sedimentation, and/or
man-made efforts
• Dam breaks -✓✓Causes: high velocity and large volumes of water released.
Caused by: (1) foundation failure due to seepage, settling, or earthquake; (2) deficient
design, construction, materials, maintenance or operation; (3) flooding exceeds capacity
of dam's spillway.
Proper design can prevent dam failures.
May have no warning.
A type of special flood hazard.
• Ice jams -✓✓Caused when warm weather and rain break up from frozen rivers, or
anytime there is a rapid cycle of freezing and thawing, which will == broken ice gets
stopped by an obstruction like a bridge or shallow area = = = ice *dam* forms.
Areas prone to it: (1) where river slope naturally decreases (2) culverts that can freeze
solid (3) channel constriction (4) headwaters of reservoirs (5) shallows where channels
can freeze.
Three hazards: (1) sudden flooding upstream, (2) movement of *floes*, (3) sudden
flooding downstream when the ice dam breaks which acts like a *dam break*
A type of special flood hazard.
• Floes -✓✓Ice chunks that can push over trees and crush buildings