A floodplain is an area of land near water bodies (rivers, lakes, etc.) that is flooded when the water body is too full. Examples of floodplains include low lying lands that are flooded/inundated with water when a river spills over its banks or when lake levels rise due to storm surge, or significant precipitation. Floodplains are natural features that allow flow to spread across the landscape, limiting flooding and erosion potential.

For more information, please visit https://npca.ca/watershed-health/floodplain-mapping.

Knowing which areas will be inundated by flood waters is an important tool for land use planning and emergency management. This knowledge helps guide sensitive land use away from high-risk areas, and for areas where historical development has already occurred, helps us identify ways to mitigate flood risk, all with the aim of better protecting people, property, and the resilience of our city for generations to come.

For more information, please visit https://npca.ca/watershed-health/floodplain-mapping.

The regulatory flood plain is the approved standard used in a particular watershed to define the limit of the flood plain for regulatory purposes. This standard is defined by the Ontario Ministry of Natural Resources and Forestry.

The NPCA defines the flood hazard as the 100-year flood event. The 100-year flood event is a frequency-based flood event that is determined through an analysis of precipitation, snow melt (or a combination thereof) having a return period of once every 100-year on average (or having a 1% chance of occurring in any given year). The 100-year flood event is the minimum acceptable standard in Ontario for defining the regulatory floodplain. In our area the amount of rainfall varies geographically, with the southern part of the peninsula generally experiencing a greater annual average amount of rainfall than the northern part. That being said, the 100-year storm produces approximately 100mm (4 inches) of rainfall over 12 hours. This amount varies slightly depending on where you are in the watershed.

There are three exceptions where the NPCA defines the flood hazard as the Hurricane Hazel event (also known as the Regional Flood). NPCA uses the Regional Flood to define the floodplain limits for Beaverdams Creek, Shriner’s Creek, and Ten Mile Creek all within the City of Niagara Falls. The Regional Flood is anticipated to produce approximately 275mm (11 inches) of rainfall over 12 hours.

A hydrology model simulates the effect of this amount of rainfall as if it were over each watershed, taking into account the topography, soil type, land-use, and other characteristics to determine how much water would end up in our rivers and streams. A hydraulic model then looks at where this water would go, and what areas would be inundated. The inundated area for the regulatory storm is called the regulatory flood plain.

For more information, please visit https://npca.ca/watershed-health/floodplain-mapping.

To check if your property is in the study area, please view the study area.

The Niagara Peninsula Conservation Authority’s goal is to produce accurate flood hazard maps using modern methods and up-to-date mapping of the study area all undertaken by experienced professional engineers. The NPCA uses these flood hazard maps to help direct new development away from areas that are flood prone. All of the NPCA’s flood hazard maps are posted on the NPCA’s website and the reports are freely available.

The NPCA has no control over how insurance companies implement their polices or set their rates. All insurance companies are different and some make wide assumptions regarding the location of a policy holder’s proximity to a flood hazard. The NPCA notes that flood insurance polices and premiums vary greatly between insurance companies. The NPCA would encourage landowners to speak to different insurance companies to find a policy that is right for their particular situation.

In order to accurately model the watershed, it is important that we do surveys to measure the watercourses, especially at stream crossings like bridges and culverts.

Most crossings that could impact the floodplain are on municipal road allowances (like culverts under roads or in roadside ditches). Some crossings, however, may be on private property.

If a culvert or other crossing is located on private property, surveyors will knock on your door to discuss the work and request permission to survey it. If you choose not to participate, surveyors will respect that decision and use alternative assumptions in the flood model. They will not do work on private property without consent.

NPCA works with property owners to understand how they intend to use their property within the floodplain and if development approvals are required, to suggest solutions that balance the request with the need for risk management.

The NPCA cannot control impacts on property value and appreciates the perception that land within the floodplain has a lower value than land outside the line. As such, careful attention is given to the technical process of defining where the line falls and to ensuring that the flood line is technically accurate and defensible in order to ensure that public risk related to flooding has been minimized.

The NPCA protects people and property by identifying where flood prone areas exist (i.e. floodplain mapping).

Consistent with the Conservation Authorities Act and the Planning Act, the NPCA is obligated to regulate development in flood prone areas.

In order to regulate development in a consistent manner, the NPCA has a series of policies that determine what can happen within the regulatory floodplain.

In some cases, development or use of property may be limited in order to ensure the safety of persons or property. NPCA works with property owners to understand how they intend to use their property within the floodplain and if development approvals are required, to suggest solutions that balance the request with the need for risk management.

It is acknowledged that the “solution” may be perceived as a restriction and that there may be impacts that affect property owners; however, the goal is to minimize impact by ensuring that the location of the floodline is technically accurate.

In most of the NPCA’s jurisdiction, the 100-year flood is the Regulatory event. The goal of this project is to understand the location of that 100-year flood line. The 200-year and 350-year will also be modeled to provide an understanding of the climate resiliency of the watershed.”

The NPCA through its new Strategic Plan 2021-2031, is committed to supporting evidence-based decision-making for climate-resilient watersheds and shorelines, and protecting people and properties from natural hazards and climate impacts.

NPCA’s floodplain models, reports and mapping are freely available and important information for NPCA and other public agencies, such as municipalities, to use when assessing the potential impacts of severe weather events as a result of climate change.

If a watercourse becomes blocked through natural processes, it is the responsibility of the property owner to fix the issue; however, the NPCA cannot compel the landowner to fix the problem.

If a landowner wants to alter a creek on their property, the works require NPCA review and approval. Please see our website for more information.

The NPCA recommends that any building openings be located at least 0.3m above the regulatory flood elevation. This accounts for extreme flood events, modeling uncertainly, local flow effects, wind effects, etc.

All floodplain maps require regular review. Land use changes in a watershed, new climatic data (rainfall, etc.), policy changes, and new modeling techniques can all impact the extent of the regulatory floodplain.

In order to ‘future proof’ our modeling and account for predictable changes in land use, NPCA bases models on the land uses outlined in municipal official plans. So, if development is planned in an area that is currently undeveloped, we will model this area as already developed.

Floodplain mapping will still need to be updated in the future as development occurs, and other information becomes available.

As floodplain mapping gets updated, it is possible that development that was previously outside the floodplain is now inside. These historical developments are considered to be in compliance with NPCA policies. Work approved by the NPCA under old floodplain mapping is not revisited when new mapping becomes available.

If new developments are planned in these areas (for ex. an addition to an existing house), NPCA review and approval will be required. NPCA planning staff will work with the property owner to facilitate works within the policy framework. NPCA will always work with the most accurate and new data available.

If there are culverts or other infrastructure creating a bottleneck and worsening flooding, the NPCA will make that information available to the appropriate municipality. The NPCA, however, cannot compel the municipality (or other landowner) to address the issue.

One or more surveyors will be positioned on the road, shoulder, or ditch to determine the size of the culvert and measure the exact elevation of its top and bottom. They will also survey the creek and surrounding land elevations to ensure the crossing is modeled as accurately as possible.

Not without your permission. Before any measurements are taken, the survey team will knock on your door to request authorization to enter your property. If you choose not to allow the survey, alternative assumptions will be used in the model.

Surveying the culvert helps identify potential flow restrictions, which could cause a backup of water during flooding. This information is crucial when modeling the floodplain to ensure accurate results.

Please note that the survey teams will only take measurement and will not clean, repair or otherwise maintain the structures.