In 2016, Council adopted the Overland Flow Flood Study for the Hurstville, Mortdale and Peakhurst Wards.  Following that, Council engaged a consultant to prepare the Floodplain Risk Management Study and Plan in 2019 to identify floodplain risk mitigation options.

In October 2023, Council endorsed the Overland Flow Floodplain Risk Management Study and Plan for the Hurstville, Mortdale and Peakhurst Wards catchment.

Download links:

• Overland Flow Floodplain Risk Management Study and Plan - Volume 1 (PDF 7.19 MB) (Report).
• Overland Flow Floodplain Risk Management Study and Plan - Volume 2 (PDF 222 MB) (Figures and Appendices).

Flood maps:

• 1% AEP Flood Depth and Level Contours (PDF 74.7 MB).
• PMF Flood Depth and Level Contours (PDF 78.8 MB).
• Flood Planning Area Map (PDF 2.37 MB).

Kogarah Bay Creek Floodplain Risk Management Study and Plan was completed in 2009.

Download links:

• Kogarah Bay Creek Floodplain Risk Management Study (PDF 12.4 MB). 
• Kogarah Bay Creek Floodplain Risk Management Plan (PDF 5.84 MB).
• Kogarah Bay Creek and Overland Flow Study. Supplementary Report on Tuflow Modelling October 2009 (PDF 5.45 MB).

Download links:

• ​Beverley Park Overland Flow Flood Study (PDF 29.4 MB) was completed in 2004.
• Beverley Park Overland Flow Risk Management Study and Plan (PDF 46.5 MB) was completed in 2007.
• Beverley Park Overland Flood Flood Hazard Mapping (PDF 4.41 MB) was completed in 2020.

Download links:

• Poulton Park Overland Flow Study (PDF 7.74 MB) (2005).
• Poulton Park Overland Flow Risk Management Study and Plan (PDF 57.1 MB) - Volume 1 and 2 (2011).

Middle Bays Flood Study (Draft) was completed in 2011.

Note: This study is currently being reviewed as part of the Blakehurst & Kogarah Bay wards Flood Study. 

Moore Reserve Catchment Overland Flow Study (Draft) was completed in 2011. 

Note: This study is currently being reviewed as part of the Blakehurst & Kogarah Bay wards Flood Study. 

Severe flooding, triggered by intense rainfall, leads to overland or flash flooding. Floodwaters can cause significant damage to homes, businesses, and human life.

Flood Studies help us understand floods better. Providing tools for planning land use, responding to emergencies, and prioritising infrastructure.

The NSW State Government's Flood Prone Land Policy requires councils to find and deal with areas prone to flooding. They work to reduce risks to people and property from floods and must share this information with the community.

Local Governments must act under the NSW Flood Prone Land Policy. This aims to lessen flooding impact and liability on property owners and occupants. Increasing awareness about flooding helps people understand and plan for flood risks better.

An overland flood study is a comprehensive technical investigation of flood behaviour.

It tells us how much flooding happens in an area. Giving details about where floods go, how much water there is, and how fast it moves during floods.

This study is the first step of the NSW State Government's Flood Prone Land Policy. It happens before a Floodplain Risk Management Study & Plan, which looks into flood risks and ways to reduce them.

The study will find out which properties might flood and help plan how to stop it from happening.

The Floodplain Management Process has four main steps in the Floodplain Management Process:

1. Flood Study. This aims to find out how floods happen. Including where they flood, how deep the water is, the danger, and how likely flooding is in the area.

2. Floodplain Risk Management Study. This builds on the flood study to look at how flooding will affect the community. Identifying ways to reduce the impact of flooding.

3. Floodplain Risk Management Plan. Includes preferred flood mitigation options to manage flood risk across the catchment. Council adopts these options.

4. Plan Implementation. After planning and availability of funds, we implement the selected options. These options may include fixing problems, improving drains, setting rules for building, raising awareness, and getting ready for emergencies.

The primary aim of a Flood Study is to assess the characteristics and risk of flooding in a specific area. Through a Flood Study, Council prepares flood mapping across the study area including the number of lots that are “Flood Tagged”. Flood Tagging identifies properties at risk of flooding. It helps enforce development controls to protect against floods.

The next step involves conducting a Floodplain Risk Management Study and Plan. This study aims to find ways to reduce flooding risks for people and properties in the area. It includes options like building things to lower flood levels, making rules for development, teaching people, and improving how we handle emergencies. We share flood information with the public after we're sure our flood models are reliable.

The Flood Study is a technical investigation of flood behaviour.

The Floodplain Risk Management Study and Plan investigates strategies to manage flood risk and lessen flooding impacts on the community. These impacts may cause property damage, financial loss, inconvenience, and personal danger.

A 1% AEP (1 in 100 year) flood is a flood event that has the probability of occurring on average once every 100 years. For example: there is a 1% chance of a flood of this size occurring at a particular location in any given year.

Some parts of Australia have experienced more than one ‘1 in 100 year’ floods within a decade of each other. Within the Floodplain Risk Management Study and Plan the ‘1 in 100 year’ flood is referred to as the 1% AEP flood event.

The Flood Planning Area (FPA) is the area of land below the Flood Planning Level (FPL). 

The FPA is generally developed based on the FPL for typical residential development. Different types of development may have different FPLs applied within the FPA. In addition, development controls may vary across the FPA due to varying flood constraints.

The Flood Planning Level (FPL) is the height used to set floor levels for houses in flood prone areas. It is generally defined as the "1% AEP flood level" plus and appropriate freeboard. See the explanation of 'freeboard' below.

The FPL can be calculated as:

FPL = 1% AEP flood level + freeboard.

A freeboard is an extra height above the flood level during floods. It is included in the Flood Planning Level. This extra height helps deal with wind, waves, unforeseen blockages, and other local water effects.

Council’s flood modelling determines the extent of flooding in the catchment and the properties affected. Section 10.7 Planning Certificates identify if flood related development controls apply to the land. 

If the situation is life threatening you should call 000.

Contact NSW State Emergency Service (SES) at 132 500 or visit the SES website for help during floods, storms, or tsunamis.

Being prepared for any flood is crucial. The State Emergency Service provides advice on how to manage your flood risk.

Councils prepare Flood Studies and Floodplain Risk Management Studies and Plans based on the NSW Government's Floodplain Development Manual (2005) guidelines. We use technical and financial help from the NSW Department of Planning Industry and Environment. These plans include suggestions to reduce flooding impacts on residents and businesses in the study area.

The council implements top-priority options from the Floodplain Risk Management Plans. This is to lower flood risks. It's based on detailed feasibility studies and available funding.

There are three main ways of managing flood risk:

1. Flood modification – this approach looks at changing the flood behaviour using structures such as detention basins or drainage system improvements. 

2. Property modification – this approach includes modification to existing properties and seeks to better manage future development through land use planning.

3. Response modification – this approach focuses on increasing our resilience through better preparedness, improved warning and recovery planning. 

Most people don't need to do anything about this Floodplain Risk Management Study and Plan. Yet, property owners planning redevelopment should think about how floods might affect their project.

This might mean setting the floor levels of the development at or above the Flood Planning Level. This helps reduce the impacts of flooding.

It's unlikely that development controls will prohibit all development on flood prone land. Yet, some things need thinking about to keep people and property safe. For instance, you might have to build on a specific area of your land, raise your building to a certain height, or avoid building where flood risk is high.

Our Development Engineering team can help you understand these considerations. You can lodge an application for a flood advice letter to get the details of the flood risk of a property.

House prices vary with changes in the real estate market and are based on a large range of criteria. Such as location, size and age, and are not under the control of Council. It is the market that determines the value. This study does not prevent the sale or purchase of property. 

Studies show that an actual flood event, rather than a flood planning notation on a Planning Certificate, is more likely to have an effect on property values.

Council doesn’t put together flood studies or floodplain risk management plans for, or on behalf of insurance companies. Flood Studies are a legal requirement for Council to complete and part of our responsibilities to help manage flood risk in the community. Insurance companies may rely on their own assessment of risk and can use their own methods to identify flood risk.

Individual insurance companies possess extensive data on flood risk obtained through their own flood studies and analyses which is already reflected in the cost of premiums, irrespective of whether Council has undertaken a flood study.

Further information on flood insurance is available from Flood Management Australia.

The Probable Maximum Flood (PMF) calculates the biggest possible flood in an area by considering extreme conditions and probabilities.

It's rare and helps understand flood risks fully. It helps design critical and sensitive facilities. Such as hospitals, childcares, nursing homes, schools and emergency service facilities.

When it rains a lot at the top of a hill, the water flows downhill through low spots like gullies and channels. Even if it's slower and less deep at the top, it can still cause floods and erosion downstream.

Floods do not occur in a regular pattern. There may be a period of no floods and a period of several floods. For example, the last time the Brisbane River flooded before the 2011 disaster was in 1974. Residents who moved there in more recent times may never considered flooding an issue until the floods in January 2011.

In 1949 and 1950 Kempsey experienced the two worst floods ever recorded, within eight months of each other. Following extensive rain every water course will flood.

Members of the public can make a written submission to Council to raise flood related issues. You can provide your valuable feedback and comments by emailing Council.

Properties can be marked as being flood affected, under the Council’s policy. Regardless of the building's floor levels. This ensures that future developments match the Flood Planning Area and aren't constructed below the flood level.

Property owners or developers can seek flood level information from Council. For more details about applying for a flood advice letter, contact customer service at (02) 9330 6400 or email mail@georgesriver.nsw.gov.au.

Council designs the piped stormwater system to handle frequent minor storms. This is to reduce everyday flooding.

During major storms, overland flow paths are used to protect life and property. Building piped drainage systems for major storms is impractical and costly.

Property owners need to look after stormwater pipes, gutters, downpipes, and gully pits on their property. These must be in good condition and follow Council rules. If there's a stormwater easement on your property, keep it clear of blockages so water can flow freely.

Property owners must maintain the stormwater system on their property up to the kerb and gutter. If maintenance is needed within the footpath area, you need to apply for permission to work within the road reserve.

You can get applications at Council’s Customer Service Centre or on our Online Forms webpage.

During rainfall, water will flow along the lowest points of the land. Allowing natural overland flow from neighboring properties or public land is crucial. This water flow should not be diverted onto other properties.

Downstream property owners cannot block the flow of stormwater. If your property is downstream, you must accept the natural runoff onto your property.