Glossary: Definitions

Terms and Definitions

Term	Definition
A Zone	See Zone A.
Acquisition	A mitigation project where an asset, usually a building, is purchased by the Federal, State, or local government as a means to prevent future damages. Acquisition is often combined with demolition to eliminate future damages completely by removing the building from the flood hazard area.
Acre	Commonly used land area unit of measure (1 acre = 43,560 square feet, and 640 acres = 1 square mile).
Active Mitigation Measures	Requires human intervention to operate properly and are usually less effective than passive mitigation measures.
AE Zone	See Zone AE.
After-mitigation	The conditions that exist after a mitigation measure is implemented and the impacts of the targeted natural hazard are reduced or eliminated.
Aggregation	The process of combining two or more buildings and functions in a single BCA.
Approximate Studies	Floodplain mapping that contains the approximate delineation of the 100-year floodplain boundaries. There are no BFEs and floodway delineations. There are no computer modules associated with an approximate study.
Architectural Elements	Exterior elements on a building or structure, including cornices, corbels, decorative features, and lighting. These and other architectural elements are common among historic, unreinforced masonry buildings. Such elements are generally constructed of stone or other heavy, brittle materials, and often fail during an earthquake due to poor anchoring or bracing.
Assets	Physical elements (i.e., buildings, infrastructure, or utilities) that have potential for damage from natural hazard events.
Average Occupancy	Occupancy of a building or a room averaged over an entire year. The average occupancy of an office building will be higher over 1 year than the average occupancy of a public meeting room that is used only once per month.
B Zone	See Zone B.
Barrier	A man-made structure between an asset and the flood source that blocks floodwaters from coming into contact with the asset. Examples include earthen levees and concrete or masonry floodwalls. Levees or floodwalls may completely surround an asset or tie into high ground at each end.
Base Flood	A flood having a 1 percent (or 1 in 100) chance of occurring in any given year. It is also referred to as the 100-year flood and is the basis for the NFIP administered by FEMA.
Base Flood Elevation	See BFE.
BCA	Benefit-Cost Analysis. A method for determining the potential positive effects of a mitigation measure and comparing them to the cost of the measure. With the FEMA BCA modules, the positive effect is a reduction in future damages from natural hazards. This is the benefit of mitigation. The BCA can also be used to compare alternative projects to determine which is the best alternative from a fiscal standpoint.
BCA Module	The calculations, standard and default values, and methodologies that combine to determine the BCR of a proposed mitigation project in accordance with FEMA BCA requirements and guidelines. The modules are used to determine the required cost-effectiveness of proposed mitigation projects across multiple FEMA Mitigation Grant Programs.
BCAR	Benefit-Cost Analysis Re-engineering. The re-engineering of the FEMA BCA Program.
BCR	Benefit-Cost Ratio. This ratio is the present value of net project benefits divided by the project costs and is the result of a BCA. A ratio of 1.0 or greater indicates the project is cost effective; a ratio of less than 1.0 indicates the project is not cost effective.
Before-mitigation	The natural or current conditions existing prior to the implementation of a mitigation measure. Under this condition, the asset is unprotected from natural hazards.
Benchmark	Date when a building code began to contain lateral force resisting requirements sufficient for a life safety performance level. Knowing the building type, date of construction, date of the building code used, and a history of seismic upgrades, a building owner can determine if their building is pre- or post-benchmark.
Benefits	Future losses prevented or reduced by a mitigation project. The benefits counted in a BCA are the present value (in dollars) of the sum of the expected annual avoided damages over the project useful life.
BFE	The Base (100-year) Flood Elevation having a 1 percent chance of being exceeded in any given year. The BFE is determined by statistical analysis for each floodplain area and designated on FEMA FIRMs
Bounded Analyses	Methods for streamlined BCAs of hazard mitigation projects. See the Tutorial Section for more information.
Braced Frames	Braced building frames are generally constructed with steel diagonal braces that provide lateral load resistance, and are most commonly encountered in rigid steel frame buildings.
BRV	Building Replacement Value (i.e., the cost to replace the building with a functionally equivalent building of the same size, based on the current cost of labor and materials). The BRV is not the same as the current market value of the building.
Building	A structure that has walls and a roof and is occupied on a regular basis.
Building Area	The square footage of the enclosed building. This value includes heated and unheated, but excludes open porches, decks, and carports.
Building Envelope	The area that separates conditioned space from unconditioned space. In this picture, the "building envelope" is the area surrounded by the insulation. The code is only concerned with the "building envelope".
C Zone	See Zone C.
Calibration Point	In a BCA, a data point that is known to be accurate, and upon which other elements of the analysis may be based.
Code of Federal Regulations	A Federal government coding system to identify Federal agency regulations published in the Federal Register. 44 CFR includes all regulations regarding FEMA.
Community	A city, village, town, township, borough, parish, county, or other legal governmental entity with the statutory authority to enact floodplain regulations and participate in the NFIP.
Construction Date	The year construction of the building started.
Continuity Premium	A multiplier (or adjustment) that places a higher dollar value on critical services for BCAs. Non-essential services, such as a library, are valued at the daily cost of providing the services. However, services such as fire, police, and medical, which are essential to the post-disaster response and recovery, are worth more to the community in the immediate post-disaster period. Such services are valued more highly by adding a continuity premium or a multiple of the normal daily cost of services.
Cost effective	In the context of BCAs, when the benefits of a hazard mitigation project exceed the project costs (i.e., BCR > 1.0).
Critical Services	Services that either directly affect life safety or services which, if lost, would have a large economic impact on a community.
Cross-section	Surveyed information that describes the geometry of the watercourse and the floodplain at a particular point along the watercourse.
Datum	A common vertical elevation reference point, usually in relation to sea level.
DDF	Depth-Damage Function, also known as a Depth-Damage Curve. A way of expressing expected flood damages for various types of buildings, their contents, or their functions at different water depths. For floods, this relationship is expressed as depth versus percentage damage to the element being considered.
Demolition	The destruction and removal of an acquired property as a means to eliminate future damages from natural hazards.
Demolition Threshold	The amount of damage, expressed as a percentage of the BRV, at which a building is considered a total loss and would not be repaired. In general, buildings that are old or in poor condition have lower demolition thresholds than new or high-quality buildings.
Depth	For floods, the depth of flooding (in feet) above the first floor elevation. For earthquakes, the distance, in miles below sea level, to the point of origin (hypocenter) of an earthquake. A default depth for shallow earthquakes is 20 miles below sea level.
Detailed Studies	Floodplain mapping that contains detailed delineation of the 100-year floodplain boundaries. The mapping includes BFEs and floodway delineations, and is based on computer models and topographic (or elevation) data.
DFE	Design Flood Elevation.
Direct Benefits	The reduction or prevention of future losses to buildings, contents, or public facilities from natural hazards.
Discharge	Volume of water flow measured in cubic feet per second (cfs).
Discount Rate	Used in FEMA BCAs to determine the “Net Present Value” of benefits. Discounting facilitates accurate comparisons of benefits that may occur in the future to the costs of a project, which most often occur immediately or in the near term. For FEMA-funded projects, the rate is set by the Federal OMB.
Displacement Costs	The costs when occupants (of residential, commercial, or public buildings) are displaced to temporary quarters while damage is repaired. These costs include rent and other monthly costs, such as furniture rental and utilities, and one-time costs, such as moving and utility hook-up fees.
Displacement Time	The time during which occupants are displaced to temporary quarters while damage is repaired.
DMA 2000	The Disaster Mitigation Act of 2000, passed in October 2001, focuses on taking action to reduce the impact of hazards before disasters occur. The objective of DMA 2000 is to help Federal and State reviewers evaluate mitigation plans from different jurisdictions in a fair and consistent manner, and to help States and local jurisdictions develop new mitigation plans or modify existing plans.
Dry Floodproofing	Any combination of mitigation measures added to or incorporated into an asset below the BFE to prevent flood damages. This approach completely seals the interior of a building by making the exterior walls substantially impermeable to the passage of floodwater. Although floodwater may touch or surround the asset, there are no damages and the interior remains dry. For existing assets, this is also known as retrofitting. Dry floodproofing is typically used in areas subject to short-duration, low-level flooding.
Ductility	The physical property of certain construction elements, such as wood or steel, to withstand large deformations without failing.
Duration	The length, in time, of an earthquake, flood, or other natural hazard. This can affect the severity of damages to buildings and infrastructure. In general, shorter durations result in less damage.
Elevation	The raising of a building to place the lowest floor at or above the designated DFE on an extended support building or fill.
EMA	Emergency Management Agency.
EOC	Emergency Operations Center.
Epicenter	The point on the earth’s surface directly above the focus (or hypocenter) of an earthquake.
Exposure	The quantity, value, and vulnerability of the built environment (i.e., inventory of buildings and infrastructure) in a particular location subject to one or more hazards.
FBFM	Flood Boundary and Floodway Map. An official map of a community that contains the delineations of the regulatory floodway.
FEMA BCA Program	The methodologies, modules (i.e., software), module standard and default values, guidance documents, user guides, analyst tools, and FEMA policy memorandum that provide specific requirements and guidance for preparing FEMA BCAs.
FEMA Mitigation Grant Programs	Grants provided to States and local governments to implement long-term hazard mitigation measures. The purpose of the programs is to reduce the loss of life and property due to natural disasters. These programs include Flood Mitigation Assistance (FMA), Hazard Mitigation Grant Program (HMGP), Pre-Disaster Mitigation Program (PDM), Repetitive Flood Claim (RFC), and Severe Repetitive Loss (SRL).
FFE	First Floor Elevation or Zero Flood Depth. This is the elevation of the top of the lowest finished floor in a building. The relationship between the FFE and the BFE at a site determines the extent of flood risk. This elevation does not consider basements or crawl spaces.
FHBM	Flood Hazard Boundary Map. An official map of a community, on which FEMA has delineated the approximate boundary of the 100-year floodplain.
FIRM	Flood Insurance Rate Map. An official map of a community, on which FEMA has delineated the 100-year (1 percent annual chance) floodplain and insurance risk premium zones. Newer FIRMs include floodway boundaries.
FIS	Flood Insurance Study. The FIS consists of three parts: FIRM, FBFM, and the FIS report. The FIS provides background on the study, estimated flood discharges (in cubic feet/second) for various frequencies (e.g., 10-year, 50-year, 100-year, 500-year), and the flood profiles for each of the flood frequencies.
Flash Flood	A flood in hilly areas that arrives at a location very quickly (minutes instead of hours) after a heavy rain. This can also occur in urban areas where pavement and drainage improvements speed rainfall runoff to a stream.
Flood	For NFIP purposes, a partial or complete inundation of normally dry land areas from: Overland flow of a lake, river, stream, creek, slough, or ditch. The unusual and rapid accumulation of rainfall runoff or snowmelt. Mudflows or the collapse of shoreline land.
Flood Fringe (or Floodway Fringe)	The portion of the floodplain located between the floodway and floodplain boundaries.
Flood of Record	The highest known recorded flood elevation for a location.
Flood Profile	A graph showing the plots of water surface elevations vs. stream distances for each flood frequency published in an FIS report.
Floodplain	The area of water and land inundated during the highest point of the base, or 100-year, flood.
Floodwall	A barrier constructed of flood-damage-resistant material, such as concrete or masonry block, designed to keep floodwaters away from a building.
Floodway	The stream channel and that portion of the adjacent floodplain that must remain open (i.e., free of development) to allow conveyance of the 100-year flood.
Floodway Data Table	The table in an FIS that provides detailed information for each mapped cross-section studied in detail.
FMA	Flood Mitigation Assistance. A mitigation grant program (FEMA). http://www.fema.gov/government/grant/fma/index.shtm
FPE	Flood Protection Elevation. The elevation to which a building must be protected from flood damage through elevation or floodproofing. The FPE is usually the BFE plus 1 to 3 feet of freeboard.
Fragility Curves	Detailed seismic vulnerability analyses of buildings, non-structural components, or infrastructure. Fragility curves define the probabilities of damage for specified damage states at various levels of ground acceleration.
Freeboard	Additional height, above and beyond what is required by a building code or the NFIP, to account for flood heights above the BFE due to wave action or the limitations used in determining flood elevations.
Frequency	The interval at which a particular event occurs. For example, the frequency of a flood that has a 2 percent chance of occurring each year is 1 in 50 years (1.0 / 50 years = .02), or a 50-year event.
Fujita Scale	The Fujita Scale (F-scale) is an empirical scale that measures tornado intensity based on the estimated magnitude of damages caused by the tornado.
Full Data Module	The FEMA Full Data (or FD) BCA module utilizes FIS data to establish risk while providing the most accurate BCA results. The FD module (also referred to as the Engineering Method) is used primarily to conduct a best data analysis.
Functional Downtime	The time period during which services are lost.
GIS	Geographic Information System. Electronic mapping based on latitude and longitude coordinates.
Hazard	In the context of BCA, a naturally occurring phenomenon (flood, wind, earthquake, etc.) that poses a risk of asset damages, economic losses, or casualties. The impact (low vs. high) of a hazard is determined by its probability and severity.
Hazard Mitigation	Reduction of the risk of natural hazards through the implementation of projects or procedures that reduce or prevent future damages.
HAZMAT	Hazardous materials.
HAZUS	Hazards-United States. FEMA software for hazard analyses based on GIS mapping.
H&H	Hydrology (the study of rainfall runoff) and Hydraulics (the study of moving water and flood elevations).
High Water Mark	Peak elevation of a flood, as noted by water lines, mud lines, or debris lines on the outside (and in some cases, the inside) of buildings and structures, trees, bushes, lawns, floodwalls, culverts, or bridges.
HMGP	Hazard Mitigation Grant Program (FEMA). http://www.fema.gov/plan/mitplanning/index.shtm
HVAC	Heating, ventilation, and air-conditioning.
Hydraulics	The study of moving water and flood elevations. A hydraulic analysis within an FIS calculates how high and how fast a flood discharge flows.
Hydrology	The study of rainfall runoff, groundwater recharge, and snow melt, which determines the quantity of water in a watercourse.
Hypocenter	The point of origin of an earthquake (the location at which rupture begins).
Indirect Benefits	In the context of hazard mitigation, the reduction in damages from natural hazard events that are not directly caused by the event itself.
Inelastic Deformation	Deformation of a structural element where the element does not return to the original shape after the force is removed. This may be the result of large forces during and earthquake that are far in excess of normal structural loading conditions.
Inflation	In the context of BCAs, the process of converting past damages to present-day values by using a factor such as the Consumer Price Index. Usually used to compare past, present, and future values on a common basis.
Intensity	Intensity measures the strength of shaking produced by an earthquake at a given location. It varies depending on not only the magnitude of the earthquake, but on local soil conditions and the distance from the epicenter.
Inundation	Flooding due to the failure of dams, levees, reservoirs, water transmission lines, or large water tanks.
Levees	A man-made barrier of constructed and compacted soil designed to keep floodwaters away from a building or structure.
Level of Protection	The recurrence interval (such as a flood frequency risk) or physical extent to which a mitigation project offers protection.
Life Safety	Avoidance of potential casualties by mitigation that prohibits or reduces the potential for structural failure and falling building elements or contents.
Limited Data Module	The FEMA Limited Data (or LD) BCA module requires historical damage data for two or more events, and provides results that are less accurate than those of the Full Data (FD) module. The LD module (also referred to as the frequency damage method) may be used to conduct bounded or best data analysis when FIS or other hazard frequency data are not available, and is applicable to most hazards (e.g., floods, landslides, ice storms, snow, etc.).
Liquefaction	Occurs when loose, wet, granular soil is shaken by an earthquake and becomes so unstable that the soil is transformed into a nearly fluid mass.
LOMC	A Letter of Map Change is an official document issued by FEMA in response to a request to revise or amend the effective FIRM or FHBM (and occasionally, the FIS report) to remove a property from the 100-year floodplain, or reflect changed flood conditions.
Loss of Function Damages	Costs and direct economic impacts that occur when physical damages are severe enough to interrupt the function of a building or other facility.
Loss of Public Services	Costs valued at the cost of providing services, plus a continuity premium, for services that are critical to immediate disaster response and recovery.
Lower Bound Analysis	A BCA screening technique that counts only the most direct or clearly documented benefits. This includes the lowest reasonable estimate of benefits associated with a proposed mitigation measure, and is generally used to indicate that a mitigation measure is cost effective.
Magnitude	Measure of the strength or the amount of energy released at the source of an earthquake, which can be expressed as a single number for each earthquake.
Maintenance Cost	The long-term costs of maintaining the effectiveness of a given mitigation measure. Maintenance costs are especially important in determining the true value of a non-structural earthquake mitigation project.
Mitigation	Measures taken to reduce or eliminate the risk of damages, economic losses, or casualties.
MMI Scale	The Modified Mercalli Intensity scale, which is a qualitative, descriptive scale that measures earthquake intensity.
Monetize	To express in terms of money, usually done to compare actions or results of actions that are not comparable in other terms.
MSC	The Map Service Center (FEMA) provides flood hazard mapping information to the public at: http://www.msc.fema.gov/
Net Benefits	The total benefits of a mitigation project minus the total project costs.
Net Present Value	The benefits of a mitigation measure that are counted into the future (for the duration of the project useful life) and then discountedusing an OMB-established discount rate.
Net Social Benefits	A term used to describe the kind of benefits that may be counted legitimately in BCAs for federally funded projects.
NFIP	National Flood Insurance Program. A voluntary program created by Congress in 1968 and administered by FEMA to reduce the loss of life, property damage, and rising disaster relief costs due to flooding.
NGVD 1929	National Geodetic Vertical Datum of 1929, which is a national elevation datum used by the NFIP.
NOAA SPC	The National Oceanic and Atmospheric Administration Storm Prediction Center monitors and forecasts severe and non-severe thunderstorms, tornadoes, and other hazardous weather phenomena across the contiguous United States.
Non-Recurring Event	A one-time hazard with no calculable recurrence interval.
Non-Structural Building Elements	Building or structure elements that will not cause the building or structure to collapse if the elements fail. These include exterior or interior elements, such as electrical, mechanical, plumbing systems, decorative features, and contents.
Non-Structural Flood Protection Measures	Administrative means of controlling flood damages, such as applying development regulations, enforcing building codes, land planning, property acquisition, building relocation, and minor modifications to existing buildings.
Non-Structural Seismic Hazard Mitigation Projects	Projects that improve, strengthen, or brace non-structural elements of a building or a structure to reduce damages, losses, and casualties during an earthquake. This includes retrofitting, bracing, or reinforcing the non-structural elements of a building or structure.
OMB Circular No. A-94	The OMB guidance document for Federal agencies that addresses cost-effectiveness and BCAs.
Ordinary Services	Services or functions that could be interrupted without resulting in significant life safety or economic impacts on a community.
PA	The FEMA Public Assistance Program provides a source of funds for States and local governments to implement hazard mitigation measures after a major disaster declaration. The use of these funds is limited to public facilities that have been damaged by the declared disaster event. The PA Program is authorized under Section 406 of the Stafford Act.
Parapets	The vertical extension of a wall above a roof. Brick or masonry parapets, typically mounted along the tops of unreinforced masonry buildings. Parapets can provide a firebreak between adjacent buildings and ornamentation. They are heavy, brittle, and typically collapse near the centers of long walls or at corners.
Passive Mitigation Measures	Mitigation measures that require no human intervention to be effective and are usually more effective than active mitigation measures.
P-Delta Effect	Excess building or structure horizontal displacement during an earthquake that can bring the building out of plumb and allow the force of gravity to deform the building or structure further. The P-Delta Effect tends to increase structural damage.
PDM	Pre-Disaster Mitigation. A grant program (FEMA). http://www.fema.gov/government/grant/pdm/index.shtm
PGA	Peak Ground Acceleration during an earthquake.
Ponding	Rainfall or snowmelt runoff that collects in natural ground depressions, creating a temporary pond.
Primary Effects	Ground motion due to seismic shaking and soil effects (settlement, displacement, or liquefaction).
Probability	The likelihood that an event will happen. In BCAs, probability is often expressed either as the annual percentage chance that an event will occur, or as the number of years required to “accumulate” a 100 percent chance of occurring.
Project Cost	The total cost of a mitigation project, including an applicant’s share. These costs include such items as land or right-of-way acquisitions, construction and materials, design, testing, permits, project management, and equipment. In most BCAs, all future benefits are counted, so all project costs should be counted as well.
Project Useful Life	The estimated amount of time (in years) that the mitigation action will be effective.
Proximity	The distance from the epicenter of the earthquake and nearby earthquake faults to a specific location. In general, the closer the location is to the epicenter, the greater the damage.
PVC	Present Value Coefficient. This combines the effect of the discount rate and the useful lifetime of a mitigation project to determine the net present value of benefits.
QWTP Model	The Quasi-Willingness to Pay Model is the primary economic model used in determining the value of lost public function in BCA. The model is based on the idea that the value of public functions can be approximated by what a community pays for the services.
Reconstruction	The construction of a new building on an old foundation or the slab of a building that was moved to a new location, destroyed, damaged, or demolished on its original site.
Recurrence Interval	The average or mean time in years between the expected occurrence of an event of specified intensity. See also return period.
Regulatory Floodway	See Floodway.
Rehabilitation	An improvement to an existing building that does not affect the external dimensions.
Relevant Occupancy	The average occupancy of a potential fall area within a building during an earthquake. (This is not peak occupancy or the occupancy of the entire building.)
Relocation	A mitigation measure designed to physically move a building to a new location outside of an identified floodplain.
Relocation Costs	The costs incurred for moving to temporary quarters while the mitigation project is being implemented or constructed.
REO	Regional Environmental Officer (FEMA).
Replacement Value	The cost to build or repair a building of a given size, type, and amenity, including both materials and labor. Several standard sources provide this information, including the Marshall & Swift Residential Cost Handbook, the R.S. Means Square Foot Residential Costs, and local building officials, among others.
Residual Risk	The expected future damages that remain after a mitigation project is in place. Some kinds of mitigation projects, such as elevation or floodproofing, do not eliminate all flood damages.
Retrofitting	Rehabilitation or reconstruction of an existing building to provide damage protection from natural hazards such as floods or earthquakes.
Return Period	The average or mean time in years between the expected occurrence of an event of specified intensity. The mean recurrence interval.
RFC	Repetitive Flood Claims. A mitigation grant program (FEMA). http://www.fema.gov/government/grant/rfc/index.shtm
Richter Scale	Charles Richter invented the original scale used to measure earthquake magnitude. The Richter Scale is a logarithmic scale, meaning that an increase of one unit of magnitude represents a 10‑fold increase in wave amplitude on a seismogram, or approximately a 30-fold increase in the energy released.
Risk	The potential for damages, losses, and casualties arising from hazards. Risk results from the combination of hazard and exposure.
Riverine Flood	Flooding that occurs along a river, stream, or other non-coastal watercourses.
Secondary Effects	Additional (after primary) indirect earthquake effects that include landslides, tsunamis, fire, hazardous material incidents, and inundation.
Seismic Damage Functions	Defines the percentage of damage from an earthquake relative to the replacement value.
Seismic Hazard	The frequency and severity of damaging earthquakes.
Seismic Risk	The threat to the built environment, in the form of damage, economic losses, and casualties, caused by earthquakes.
Seismograph	Equipment used to measure the magnitude of an earthquake.
Severity	The relative strength of a negative event, such as a flood, hurricane, earthquake, or wildfire. There is nearly always a measure of severity associated with probability calculations.
SFHA	Special Flood Hazard Area. The base or 100-year floodplain shown on a FEMA FBFM, FHBM, or FIRM.
Shear Walls	Large structural walls that carry forces from floor and roof systems across the building and down to the foundation and the supporting soils. Shear walls are typically constructed of reinforced concrete, but may also be constructed of reinforced masonry or even wood framing. Braced frames consist of beams and columns with stiff diagonal braces that perform the same job as shear walls, but with less material.
Soft First Story	The lowest floor of a building containing large open spaces, (for parking or interior storage), that are used to support one or more heavier upper floors.
Soil Displacement	Lateral (horizontal) spreading of soil due to earthquake ground motion.
Soil Settlement	Vertical (downward) spreading of soil due to earthquake ground motion.
SPC	See NOAA SPC.
Spectral Acceleration	Earthquake-induced acceleration that, at specified frequencies or periods, accounts for energy dissipating (damping) characteristics of buildings.
SRL	Severe Repetitive Loss. A mitigation grant program (FEMA). http://www.fema.gov/government/grant/srl/index.shtm
Stafford Act	This act established several of FEMA’s programs, including the Hazard Mitigation Grant Program and PA Program. Among other requirements set out in the Stafford Act is one mandating that projects funded with HMGP grants must be cost effective.
Storm Surge	An abnormal rise in sea level accompanying a hurricane or other intense storm, and whose height is the difference between the observed sea level and the level that would have occurred in the absence of the storm. Storm surge is usually estimated by subtracting the normal or astronomic high tide from the observed storm tide.
Storm Tide	The level of sea water resulting from the astronomic tide combined with the storm surge.
Structural Building Elements	Building or structure elements that act as a skeleton to support the rest of the building or structure. These include the foundation, load-bearing exterior and interior walls, beams, columns, floor systems, and roof systems. A failure of one or more structural elements may result in the collapse of the building or structure.
Structural Flood Control Measures	Projects that control floodwaters by construction of barriers (floodwalls or levees), flood storage areas (dams or detention and retention ponds), or channel improvements (widening, straightening, or stabilizing the banks).
Structural Seismic Hazard Mitigation Projects	Projects that improve, strengthen, or replace structural elements of a building or other structure to better resist earthquake forces. This includes retrofitting, bracing, or reinforcing the structural elements.
Structure	A building with sides and a roof, but generally not occupied on a regular basis, with the exception of maintenance activities. An example is a stormwater pump house.
Substantial Damage	Damage, of any origin, sustained by a building that results in damage equal to 50 percent or more of the pre-damaged building value.
Substantial Improvements	Any improvement, new construction, rehabilitation, or addition that equals or exceeds 50 percent of the pre-improvement building value. This includes buildings that have been repaired after suffering substantial damage.
Tilt-Up Structure	A building or structure constructed with pre-cast concrete walls that are tilted up into place.
Unit Cost	Cost per unit of measurement, such as dollars per square foot.
Upper Bound Analysis	A BCA screening technique that counts only the highest possible estimate of benefits associated with a proposed mitigation measure. This is generally used to indicate that a project is not cost effective.
V Zone	See Zone V.
Value	The monetary worth of a physical element or a community function. This is one of the three components of risk.
VE Zone	See Zone VE.
Vulnerability	The tendency of something to be damaged when it is affected by a natural hazard. This is one of the three components of risk.
Water Surface Elevation	The elevation, expressed in feet above sea level, of the surface of the water in flood events of various frequencies.
Wet Floodproofing	Modification of a building to allow short-duration, low-level floodwaters to enter the building in a way that minimizes damage to the building and its contents.
Wind-Damage Function (WDF)	The estimated building or contents damage, expressed as a percent of BRV or total contents value, for the range of storm classes from 0 to 5.
X Zone	See Zone X.
Zone A	The 100-year floodplains (except Zone V areas) shown on a community's FIRM. There are five types of Zone A areas: A: An approximate 100-year floodplain where no BFEs or 100-year flood elevations are provided. A#: Numbered Zone A areas (e.g., A7 or A14), where the FIRM shows a BFE in relation to the NGVD. AE: 100-year floodplain where BFEs are provided. Zone AE delineations are used on newer FIRMs instead of A# Zones. AO: 100-year floodplain with sheet flow,ponding, or shallow flooding. BFE depths (feet above grade) are provided on the FIRM.AH: 100-year floodplain with shallow flooding. BFEs in relation to NGVD are provided on the FIRM.
Zone A (Coastal)	Flooding in coastal areas that are affected by wave heights of 3 feet or less.
Zone B	Area of moderate flood hazard usually depicted on FIRMs as floodplain areas between the limits of the 100- and 500-year floods. Zone B areas are also used to designate base floodplains with modest hazard, such as those with average depths of less than 1 foot, or with drainage areas of less than 1 square mile.
Zone C	Area of minimal flood hazard usually depicted on FIRMs as areas above the 500-year flood level. Zones B and C may have flooding that does not meet the criteria to be mapped, and may include localized ponding or drainage problems.
Zone V	Flooding in coastal areas that are affected by wave heights greater than 3 feet. The 100-year floodplain subject to coastal high hazard flooding. This is mapped in the portion of a coastal floodplain subject to storm-driven velocity of 3 feet or more in height. There are three types of V Zones: V, V#, and VE, which correspond to the similar Zone A designations.
Zone X	Newer FIRMs contain shaded and unshaded Zone X floodplain areas. These designations replace the previous Zone B (shaded Zone X) and Zone C (unshaded Zone X).