LEVEE by Perennial
Some knowledge between you and known flood risk.
A free flood map for NSW property owners and industry professionals. LEVEE brings the flood studies your council has already published into one map and explains them in plain terms: how far a flood reaches, how deep it gets, and which planning rules follow.
The promise behind it, in Perennial's own words: “if you cannot understand our advice, we have not finished our job.”
What the map can and cannot tell you
Every piece of ground is in one of three states, and the difference between the last two is the most important thing on this site.
Mapped as flood affected
A published study covers this ground and maps flooding on it. The map draws the extent, and FreeBoard can say how the planning rules apply.
Studied, no flooding mapped
A published study covers this ground and maps no flooding at this spot. That is an answer: the modelling looked here and drew nothing.
No study covers this ground
Nothing has been published here under an open licence, so the map is silent. Silence is not an answer: an area being absent from the map does not mean it does not flood.
One colour language, statewide
Every council chooses its own colours, its own catchment names and its own platform, and none of them agree. A resident who moves thirty kilometres meets a different colour language for the same risk. LEVEE draws every council area in one ramp.
One council
High risk
Medium risk
Low risk
A neighbouring council
High risk
Medium risk
Low risk
LEVEE, statewide
Frequent
Uncommon
Benchmark
Rare
Maximum
The same three categories of risk, drawn by two neighbouring councils, can share no colour at all. Neither palette is wrong: there is no convention for councils to follow, and the point is the absence of one, not the choices any council made. LEVEE draws one ramp for every council area, one hue, darker for floods that happen more often, validated for colour vision deficiency.
Expression of interest for professionals
LEVEE is open for consultation with suitably qualified professionals while accounts are provisioned: flood and water engineers, councils, government agencies, and the insurance and finance sector. You would get the practitioner view of the map, and the ability to contribute to it.
What LEVEE asks of councils and of consultants, and what it never asks for, is set out on the contribution page. The short version: no model files, no reports.
Tell us who you are and what you work on, and we will be in touch about access.
What LEVEE stands for
Five things a flood study can tell you about a place. They are the five headings on the map, in this order, and they spell the name.
- Level
- How high
- Extent
- How far
- Velocity
- How fast
- Exposure
- How safe
- Events
- How often
Plain names for flood events
The industry describes floods by their chance of happening in any one year. That is accurate and widely misread, so the map pairs each probability with a plain name and with the chance that matters to a person: whether they will see that flood across a lifetime.
| Name | Chance in any year | Chance across 80 years | What it means |
|---|---|---|---|
| Frequent | 20% chance in any year | More than 99% | A flood most people will see more than once. The 20% AEP event. |
| Uncommon | 5% chance in any year | About 98% | A serious flood that is still likely within a lifetime. The 5% AEP event. |
| Benchmark | 1% chance in any year | About 55% | The 1% AEP event, which NSW flood planning is built on. Drawn on the map as the Benchmark Flood. |
| Rare | 0.2% chance in any year | About 15% | Beyond the planning benchmark, but still a real possibility. The 0.2% AEP event. |
| Maximum | Not given an annual chance | Not quantified | The largest flood that could conceivably occur. Drawn on the map as the Maximum Floodplain. |
Flood events do not take turns. A 1% chance in one year does not reduce the chance the following year, which is why the old habit of describing the planning benchmark as a once-a-century event is retired. The lifetime column is calculated from the annual chance compounded across an average 80 year lifespan.
What LEVEE offers
LEVEE Map
A simple map of the known flood risk at your property.
For people who are not flood engineers. Owners, buyers, planners and anyone assessing a site.
Plain terminology instead of technical labels. A small number of clear layers rather than everything at once. It answers whether flooding is mapped at an address, how serious it is, and where to go next.
Live for six council areas plus the Hawkesbury-Nepean valley, across greater Sydney, the Illawarra and the Hunter, growing study by study.
View
LEVEE Pro
Demo mode onlyA detailed map of adopted flood study data and the model parameters behind it.
For flood engineers and technical users.
Full results from adopted council studies: levels, depths, velocities, hazard classes and the full range of design events. Each study also carries the input parameters and assumptions behind it, cited to the report it came from.
View the demo
LEVEE Connect
A directory of consultants actively working in your area.
A visual and spatial directory, shown on the same map, in two forms.
Where an adopted council study covers the catchment, Connect shows the council's catchment and the consultants who have completed approved work there using that council data.
Where no adopted council study exists, Connect shows the study area of each approved site specific study. In those areas a consultant's own work is often the only flood information there is.
In preparation
FreeBoard
A per-lot summary of the flood planning controls that apply to your property, drawn from the mapping in plain terms.
In preparation
LEVEE Learn
Short, interactive explainers on how floods behave. See how high and how far a flood reaches, how likely it is over the time you own a place, and why the planning rules exist.
Teaching councils
Grown from staff education sessions for council development engineers, teaching planners the fundamentals of flood risk.
Teaching professionals
Presented to planning consultancies and industry committees, whose flood planning committees informed the platform's direction.
Teaching the public
Interactive tools translating flood levels, event probability and planning terms into plain language, with the same material that trained the professionals.
Know when your area is added
LEVEE Map is live for Newcastle, Wollongong, Hawkesbury, Sutherland Shire, Wollondilly and Penrith, and the Hawkesbury-Nepean valley study covers the floodplain upstream and downstream of those areas as well. We map catchment by catchment, so an area being absent from the map does not mean it does not flood. Leave your email and we will let you know when your area is covered.