Project Brays Glossary

Project Brays Glossary


0.2% Floodplain
The area of land that has a 0.2% chance of being flooded from a bayou, stream, or creek in a given year. It is commonly referred to as a 500-year floodplain.
A combination of one or more components that provide a complete plan to reduce flood damages.
1% Floodplain
The area of land that has a 1% chance of being flooded from a bayou, stream, or creek in a given year. It is commonly referred to as a 100-year floodplain.
0.2% Rainfall
An amount of rain having a 0.2% chance of being equaled or exceeded in any given year. Also known as a 500-year rainfall
1% Rainfall
An amount of rain having a 1% chance of being equaled or exceeded in any given year. Also known as a 100-year rainfall.
A written estimate of the value of an asset or property prepared by a qualified, independent party.
Base Flood
A flood that has a 1% chance of being equaled or exceeded in any given year. Also referred to as a 1% or 100-year flood.
Base Flood Elevation
The elevation above the average sea level that waters from a 100-year flood will reach along a creek or bayou. These elevations are mapped out to create floodplains.
Benefit-to-Cost Ratio
Represents the overall efficiency of a plan and is determined by dividing the value of the annual benefit by the annual cost.
Best Management Practices
Bridge Modification
The replacement, extension, or reinforcement of a bridge in order to remove an impediment to flow or accommodate a channel enlargement.
The elimination of potential flood damages to nearby structures by acquiring and removing them.
Bypass Channel
The construction of a new channel in order to convey stormwater runoff around the area.
The measure of water capable of flowing through a channel or how much water a detention facility holds.
Capital Improvement Program (CIP)
Shows the schedule and projected funding for flood damage reduction projects.
Cellular Concrete Mats
A mat of interlocking concrete puzzle-type blocks that are placed as a lining on the sides and bottom of a channel. These mats increase the efficiency of the stormwater flow in the channel, while allowing vegetation to still grow.
A generic term for a course or passage where stormwater may be directed.
Channel Flow
The amount of stormwater flowing through a channel.
Channel Modification
A man-made change to the channel’s characteristics, typically to reduce flood damages.
Citizens Advisory Committee
A group of stakeholders who meet regularly to discuss items of importance relative to Harris County Flood Control District activities, such as a study, design, construction project or maintenance practice.
Conditional Letter of Map Revision (CLOMR) is FEMA's comment on a proposed project that would affect the hydraulic characteristics of a flooding source.
The final phase of a transaction, specifically the execution of a contract for the sale of real estate.
Closing Costs
Feeds due at the closing of a real estate sale. These fees can include property insurance, taxes, attorneys’ fees, an origination fee, an amount placed in escrow, title insurance, mortgage insurance premium, points and filing fees associated with the sale of property.
A section of a detention basin designed to operate separately from other sections of the same detention basin.
Specific items used to reduce flood damage, such as a detention basin or channel enlargement, at a particular location.
The legal process for the taking of private property.
The intersection of two or more streams.
A line on a map that joins points of equal elevation. Each contour line will increase or decrease to illustrate the identified land elevation.
The ability of a channel or other drainage element to move stormwater.
Reference to the U.S. Army Corps of Engineers, the federal agency authorized to partner with local governments to conduct major water resources projects. For more information on the Corps, visit
An acronym for downstream.
Data Collection Form
A form used to compile information from a homeowner who wishes to participate in the home buyout program. It is sometimes called a "Voluntary Acquisition Form."
A legal document that evidences a person’s ownership of and right to possess a property.
Desired Capacity
A measure of which communities need an acceptable level of flood damage reduction. This capacity is based on the extent of flooding, available land and available funding.
Detention Basin
An area of land, usually adjacent to a channel, that is designed to hold stormwater and then slowly drain it over time.
Disaster Area
When a disaster is beyond the capabilities of the local and state government, the President may declare the affected region a "disaster area." Federal assistance is made available such as temporary housing, crisis counseling, legal assistance, or even monetary help. For more on the Disaster Declaration process, visit
Discrete Segment
Describes the pieces of a large project that can be submitted for Federal reimbursement to the local sponsor.
Duplication of Benefits
A situation in which benefits are derived from two federal government-sponsored programs for the same item. Regulations prohibit the duplication of benefits in a home buyout.
A right to cross or otherwise use someone else’s land for a specified purpose.
A major subdivision of an overall flood damage reduction plan based on scheduling, financial, or geographic criteria.
The vertical distance measured from a datum to a specific point of interest. See Base Flood Elevation.
Elevation Certificate
A detailed survey of a structure’s elevation to see if it is above or below the base flood elevation. This certificate can be used to reduce the cost of flood insurance or even remove a particular structure.
A situation where a property owner extends a construction, such as a wall, fence, building, etc., on another person’s property.
Environmental Protection Agency
A third-party account used to hold a homebuyer’s funds until all specified conditions have been fulfilled on both ends of the transaction.
Existing Capacity
The measure of how much water a channel can currently carry or how much stormwater the detention facility can currently hold.
Fair Market Value
The most probably price which a property should bring in a competitive and open market. This value is determined by a licensed appraiser.
Fee Simple
Full ownership of real property by an individual or entity.
Federal Emergency Management Agency (FEMA)
The federal agency responsible for providing leadership and support to reduce loss of life and property and to protect our institutions from all types of hazards. It is also responsible for administering the National Flood Insurance Program (NFIP).
Flood Insurance Rate Map (FIRM) Panel
A map that is broken out over the entire Harris County area and is commonly used in floodplain management.
Flap Gate
A mechanical device used to control the direction of flow of stormwater and is typically used at the end of a pipe draining into a channel.
Flood Bench
A design feature in a channel that creates flatter slopes and plateaus, giving completed segments a more natural appearance.
Flood Control District
A special purpose district responsible for devising flood damage reduction plans and maintaining the primary drainage infrastructure.
Flood Insurance
A policy that will assist in the event that your home has been damaged by a flood. It is often not included in a standard homeowner’s insurance and must be paid for separately.
Flood Insurance Rate Maps (FIRMs)
Maps that show the areas with the highest probability of flooding and illustrate the extent of flood hazards in these areas. These maps are used to determine flood insurance rates.
Flood Insurance Study
Studies conducted by FEMA on the hydraulic and/or hydrologic analysis for streams within a community. This data is then incorporated into the Flood Insurance Rate Maps (FIRMs).
An area of low-lying ground next to a body of water and is subject to flooding.
Floodplain Administrator
A person within a local government jurisdiction that administers their community’s floodplain management and development regulations in accordance with the National Flood Insurance Program (NFIP).
Floodplain Management
The operation of a community program that demonstrates preventive and corrective measures to reduce the risk of current and future flooding.
An area of the floodplain that is likely to be the deepest and fastest. This area should be kept free of obstructions to allow floodwaters to move downstream.
A line formed representing the lowest point in the bottom of and along a specified length of a channel.
Fluvial Geomorphology
The study of river behavior and river-related landforms, such as riverbeds, floodplains and stream forms.
An acronym for fiscal year
Rock-filled wire baskets that form a retaining wall used to support the banks and sides of the channels.
Geographic Information System (GIS)
A computer program or programs used to store a wide variety of information and link it to a specific geographic location.
Global Positioning System (GPS)
A system that uses satellites to accurately determine the location of any point on earth, helping create the most accurate floodplain maps possible.
Greens Bayou Wetlands Mitigation Bank
A permanently protected, man-made wetlands located along Greens and Garners bayous in northeast Harris County. Wetlands are among the most productive ecosystems and perform many important functions that benefit people and wildlife.
General Re-evaluation Report (GRR)
A report submitted to the United States Army Corps of Engineers for approval of a revised project plan.
Harris County Flood Control District (HCFCD)
The flood control district responsible for devising flood damage reduction plans and maintaining the primary drainage infrastructure within the boundaries of Harris County.
Technology concerned with the conveyance of liquids through channels, pipes, and detention basins to determine properties such as stormwater depths and velocities.
The study of the properties, distribution, and circulation of the Earth’s water. Hydrological procedures are used to estimate the expected amount of water entering a drainage system.
The expected change in stormwater characteristics, velocities and depths caused by proposed changes in the watershed.
Land, buildings, and other assorted structures, such as drainage systems, that serve public use.
Insufficient Capacity
When a channel or a detention facility cannot carry or hold all of the stormwater that could potentially flow to it.
Joint Task Force (JTF)
Partnership between the Harris County Flood Control District, the City of Houston, Harris County, and the Texas Department of Transportation to address Phase 1 stormwater permit requirements.
A physical barrier constructed to protect areas from rising floodwaters.
Light Detection and Ranging (LiDAR)
A commercial technology that uses a laser mounted to an airplane to measure the elevation of the ground.
A legal claim that allows the right to keep possession of property belonging to another person until a debt owed by that person is settled.
Letter of Map Revision (LOMR)
A modification to a Flood Insurance Rate Map (FIRM), Flood Boundary and Floodway Map (FBFM), or the Flood Insurance Study (FIS) report.
An action that aims to reduce the severity of something.
A legal agreement by which a bank or other creditor lends money at interest in exchange for taking title of the debtor’s property, with the condition that the title becomes void upon the payment of the debt.
Moving Costs
Additional costs associated with moving such as packing, storage, transportation, insurance, etc.
Moving Expenses
Potentially tax-deductible expenses associated with moving due to needing to be relocated.
Municipal Separate Storm Sewer (MS4) Permit
A permit that allows stormwater control practices that will minimize the discharge of pollutants from the sewer systems.
The ability to provide more than one use, usually in reference to drainage facilities or detention basins that not only provide for flood damage reduction, but also accommodates hiking and biking trails, sports fields, and wildlife habitat.
National Flood Insurance Program (NFIP)
A program that provides low-cost flood insurance to property owners in flood-prone communities.
National Oceanic and Atmospheric Administration (NOAA)
An agency that focuses on the conditions of the oceans, major waterways, and the atmosphere.
Non-Point Sources
Indirect sources of stormwater runoff (such as roadways, yards, or agricultural areas) that can be the origins of stormwater pollution in the overall drainage infrastructure.
National Pollutant Discharge Elimination System (NPDES)
A federally-mandated permit program intended to control water pollution by regulating point sources that discharge pollutants into waters of the United States.
An acronym for Operation and Maintenance
Other Frequency Floods
There are several frequency floods that can occur. The 1% Floodplain is used as a standard for regulations, designs, and NFIP purposes.
The pipe, channel, or opening typically connected to the lowest point of the basin where water falls into another body of water, typically a drainage channel.
The condition in which the water level of a channel rises above the top of its banks and spills into the surrounding land area.
Generally a U-shaped bend or meander in a river or channel.
Refers to using current income instead of relying on debt as a way to fund projects.
Peak Flow
The maximum flow of stormwater flowing through a channel at a given location, based on a certain amount of rainfall falling in that area.
Physical Condition
A detailed listing of all of the physical aspects of a channel that can influence its effectiveness.
Point Sources
Specific conveyances such as pipes or man-made ditches that flow into, or are part of, the overall drainage infrastructure.
The process after a rainfall when water gathers in low-lying areas throughout a watershed and the capacity of the storm sewer has exceeded.
Pre-Flood Fair Market Value
The most probably price which a property should bring in a competitive and open market prior to recent flood damages.
Project Process
Includes the Feasibility Stage, Development Stage, Property Acquisition and Utility Relocation Stage, Design Stage and Construction Stage. Each of these stages require a funding allotment.
Relocation Assistance
Financial assistance and guidance provided to a qualified homeowner who needs to relocate to a comparable, safe home.
Repetitive Loss Property
Homes that have received more than $1,000 of flood insured damage two or more times in the last ten years. This results in higher priority for certain types of buyout.
Any dwellings in which people live, including single-family houses, apartment units, mobile homes and travel trailers.
Right of Way (ROW)
An interest in real property, either in fee or easement.
Land used by a public agency for public purposes, such as building roads or improving channels.
Riparian Zone
An area of land along a waterway that may be natural or engineered for soil stabilization or restoration.
Rocks or broken pieces of concrete that serve as an armor for a channel or detention basin to avoid erosion from stormwater.
Riverine Flooding
Flooding that is the result of creeks and bayous leaving their banks due to heavy rainfall.
Stormwater that has not been absorbed by the ground and flows into the local drainage system.
Section 211
See Water Resources Development Act of 1997.
Special Flood Hazard Area (SFHA)
An area on a Flood Insurance Rate Map that has been flagged as an associated risk of flooding.
Sheet Flow
A downslope movement of rainwater that forms a thin, continuous flow over relatively smooth soil or rock surfaces. Also known as Overland Flow Flooding.
Stormwater Detention Basins
An area of land that temporarily stores stormwater until it slowly drains out once the water levels recede. Detention basins are used extensively in Harris County.
Stormwater Retention Basin
An area of land that permanently stores stormwater and is often used to help replenish large underground water aquifers. Retention basins are less practical in Harris County, therefore are not common.
The gradual caving in or sinking of an area of land. As water is withdrawn from the aquifers, pressure decreases, and the clay particles begin to compress. The ultimate effect is the sinking of a land surface.
Substantially Damaged Property
Damage to a structure where the cost to repair equals or exceeds 50% of the value of the structure, excluding the land value.
The land area that drains to a smaller channel that eventually drains to the main channel. Also known as a Tributary Watershed.
Stormwater Management Program (SWMP)
A program that takes actions to reduce the discharge of pollutants in stormwater runoff.
Stormwater Pollution Prevention Plan (SWPPP)
A plan to prevent stormwater pollution by controlling sediment and avoiding erosion.
Topographic Data
Information about the various elevations of the Earth’s surface.
Texas Pollutant Discharge Elimination System (TPDES)
A state program for issuing, amending, terminating, monitoring, and enforcing permits, and imposing and enforcing pretreatment requirements.
Texas Parks and Wildlife Department (TPWD)
A state agency that oversees and protects wildlife and their habitats.
A channel through which water may move or be directed that ultimately flows into a larger channel, usually bayous and creeks.
Tributary Watershed
See Subwatershed.
Tropical Storm Allison Recovery Project (TSARP)
A joint-effort project between FEMA and the Harris County Flood Control District to gather information about Tropical Storm Allison and to create new flood hazard information for all of Harris County.
Texas Department of Transportation (TxDOT)
A government agency that is responsible for overseeing the construction and maintenance of state highways, aviation, railways, and public transportation systems.
An acronym for upstream.
Unincorporated Harris County
An area within Harris County that is not within jurisdiction of the Port of Houston Authority.
Wastewater Treatment Facility
A facility that serves the purpose of treating wastewater ranging from domestic, commercial or industrial sources.
Water Surface Elevation
The distance the water surface in a creek or bayou is above the average sea level.
Water Surface Elevation Profile
Shows the elevation above the average sea level of the 1% (100-year) or 0.2% (500-year) floodplain along all the studied stream miles in a particular watershed.
A geographical region of land that drains to a common channel or outlet, mostly creeks and bayous in Harris County.
A structure constructed to control the timing and amount of stormwater flowing into an adjacent detention basin.
Working Day
A calendar day, excluding weekends and County holidays, in which contractors are allowed to perform work on a project for a continuous period. Work cannot be performed on non-work days without District approval.
Water Resources Development Act of 1996 (WRDA), Section 211
A section of the act that gives authority to authorized non-federal agencies to take the lead on planning studies and construction of major flood damage reduction projects.