Flood extent FAQs

Although flooding can happen anywhere, the “flood extent” is an estimate of areas prone to three types of flooding.

• For fluvial flooding, the flood extent represents areas of land near a water body that is expected to flood. This is called a floodplain.
• For pluvial flooding, this represents low-lying areas and places with limited capacity for drainage or absorption that are most flood prone.
• For coastal flooding, this represents areas along the coast that could be flooded in high water and storm surge events. 

Learn more about flooding.

A flood extent map is a tool to identify areas that are at a risk of flooding under certain conditions. This mapping is an important component of becoming more resilient to floods, including to help increase public awareness of flood risks. 

The municipality initiated a process to map three types of flooding (pluvial, fluvial, and coastal) at a high level for the entire municipality. Halifax has also done more detailed modelling for the Sackville and Little Sackville River Floodplains. Both layers are shown on the map. Explore the most up-to-date information about the Sackville and Little Sackville Rivers Floodplain.

The flood extent map is generated from the 2024 CBCL study (“Creation of Coastal, Pluvial, Fluvial Flood Hazard Maps”) and shows the 1-in-20 and 1-in-100 year events. Flood extent maps are developed to assist the municipality in making infrastructure and planning decisions, and also to provide information to residents to support flood preparedness planning. These high level maps are not the same as zoning maps.

Zoning maps are those maps contained within relevant land use by-laws that show the areas where specific floodplain zones apply.  Within these zoning lines regulations and policies are typically established to protect public safety, reduce the development of flood-vulnerable assets and infrastructure in high flood risk areas, mitigate damage from flooding, and to avoid increased flood waters. 

An area that looks within or near the flood extent layers does not change the zoning or land use by-laws in any way. In the future, if any changes to zoning is required, a comprehensive process will be completed that includes extensive community engagement and more accurate flood models.

These terms refer to the statistical probability of a flood event occurring in any given year.

The 1-in-20-year event is an event that has a 5 per cent chance of happening in any given year. The 1-in-100-year event has a 1 per cent chance of happening in any given year.

It is important to remember that:

• this does not mean that once an event has happened, it can’t happen again for another 20 or 100 years; and
• this does not mean that if you live somewhere for a long time, there is only a 1 per cent chance of a flood.

Changing weather patterns, projected climate change impacts, erosion and development that does not meet flood mitigation requirements can all affect flood risk areas.

The 2024 CBCL study (“Creation of Coastal, Pluvial, Fluvial Flood Hazard Maps”) was a multi-year initiative to model and map flood hazards. This process included:

• Data collection: including historical rainfall patterns, river flow dynamics, sea-level records, infrastructure, wave, and wind conditions, and detailed topobathymetric information. Topobathymetric models look at land, water, and submerged land together using sensors and lasers to create a more accurate understanding of flood behaviour.
• Precipitation analysis: assessment of rainfall data to understand the frequency and distribution of rainfall patterns that influence pluvial and fluvial flooding. This analysis included both historical records and climate change projections to generate future scenarios.
• Pluvial-fluvial analysis and modelling: models of HRM were built to understand the interaction of rainfall, flows, and flooding. These models were developed and calibrated against historical flood events.
• Coastal analysis and modelling: advanced numerical models were created to project coastal flood hazards now and in the future. The extreme water levels include contributions of tides, storm surge, and sea level rise.
• Flood mapping: Several flood scenarios, including a range of annual exceedance probabilities and future projections were developed. These results were presented spatially to assist with planning, emergency response, and infrastructure resilience.

The flood maps also show flood extents for the Sackville and LIttle Sackville River floodplains and the Shubenacadie floodplains. Learn more about these detailed studies, including the methods to create the flood lines.

In 2018, the world’s leading scientific body on climate change (Intergovernmental Panel on Climate Change (IPCC)) released a report that indicated that the risks of climate change can be reduced by limiting warming to 1.5 degrees Celsius (°C) above pre-industrial levels. If the world continues to emit its current level of greenhouse gases (GHGs), we will breach the limit of 1.5°C of warming in just ten years.

Projections indicate Halifax will experience sea level rise, higher temperatures, more heat waves, more rain and snow, more severe storms, and more flooding events and wildfires. Extreme weather also drives other climate hazards such as, decreased snowpack and unpredictable runoff.

Climate hazards pose risks for people, the built environment, natural systems and resources, economies, livelihoods, and safety. Examples of increased risks for Halifax include:

• damage to physical infrastructure such as buildings, roads, communications equipment, and water and wastewater treatment plants;
• reduced water quality and quantity;
• stresses on agriculture and food systems;
• threats to biodiversity and ecosystem resilience;
• uncertainty for fisheries and forestry;
• physical adversity and mental health impacts;
• increased demands on emergency services;
• financial impacts on businesses and economies; and
• diminished capacity of government to effectively provide public services.

To learn more about climate change in Halifax, visit the HalifACT page.  

Flooding has many causes. The flood extents shown in this map are based on the best available data we have, but make assumptions about some flood behaviour. This may mean that some areas that have flooded in the past are not captured. The maps also show an extreme event (the "1-in-20 year"). This is different than smaller amounts of ponding that can occur in more frequent floods as water drains slowly. 

The Interactive Flood Extent Maps consider not only historical information, but also future climate projections related to climate change. In the future, the Halifax Regional Municipality is expected to experience more frequent and more intense storm events which is expected to lead to flooding beyond what we have seen in the past. This means that even though you may not have been affected by flooding in the past, you may be at risk in a changing climate. Because the expected life of many structures is often more than 100 years, the Interactive Maps include climate projections to the year 2100.

Provincial and municipal levels of government do not regulate insurance costs or coverage.

Please check with your individual insurance provider for information on coverage options. A suggested question to ask your insurance provider is: Does my insurance cover water, septic or sewer back-ups, flooding from an overland flow of a river, the accumulation of water from a heavy rainfall and extreme storms and other damage? 

Decisions concerning flood insurance are made by insurance companies through several sources of information. The Insurance Bureau of Canada (IBC) has confirmed that insurers purchase accurate, up-to-date flood mapping primarily from a private sector company that has flood maps for the entire country. This ensures a consistent set of data for insurers to price risk.

According to the Property Value Services Corporation in Nova Scotia:

“Every property in the province, regardless of its location, is assessed at market value as of a given date in accordance with section 42 of the Nova Scotia Assessment Act by Property Valuation Services Corporation (PVSC), the independent assessment authority for Nova Scotia. Property assessments are based on market evidence, e.g., sales or financial data, which indicate the annual market for different geographical areas and groupings of property. Additionally, PVSC takes into consideration the physical state of a property as of December 1 of each year to reflect any changes, such as renovations, demolitions, damage, etc. "

Questions about your property or assessment can be directed to PVSC at 1-800-380-7775 or inquiry@pvsc.ca.

Yes, this mapping is an initial step to better understanding our flood risk. For example, more comprehensive modelling has already been completed for the Sackville and Little Sackville Rivers. We will use the pluvial, fluvial, and coastal flood hazard mapping to identify areas where more investigation is needed. These maps will be continuously reviewed by municipal planning and engineering staff at regular intervals as new information and technologies become available and useable. Mapping will be updated as deemed necessary. 

Yes. Many cities in Canada and around the world are facing the same challenges. Changing weather patterns, erosion and new development can affect the flood risk areas and controls on new development are often implemented whenever financial, safety, and environmental impacts are a concern.

Open and accessible risk data is for everyone. These maps are an important tool for our municipality to prepare, mitigate, respond, and recover from floods. These maps will help residents understand flood hazards and plan for the future. These maps were funded by the municipality and other levels of government through taxes.

Researchers from the University of Waterloo surveyed 2,300 households and found that only 6 per cent know they live in a designated flood risk area. This research also found that over 90 per cent of homeowners think that floods maps should be made publicly available. Making these maps available to everyone helps with planning for future flood events and raise awareness for actions you can take.