The probability that a flood of a given magnitude or greater will occur within any given year, usually expressed as a percentage. The remaining area of flood-prone land after floodways and floodplains has been defined. Flood plans describe agreed roles, responsibilities, functions, strategies and management arrangements for the conduct of flood operations and for preparing for them.
Flood storage areas: those parts of the flood plain that are important for the temporary storage of flood waters during the passage of a flood. Indirect effects are one of the three main sources of risk in the context of flooding (the other two being inundation and inundation). Isolation is one of the three main sources of risk in the context of flooding (the other two being flooding and indirect effects).
Introduction
- Purpose
- Authority
- Area Covered by the Plan
- Description of Flooding and its Effects
- Responsibilities
Submit situation reports to SES Sydney Western Region headquarters and agencies assisting within the council area. Advise SES The Hills Local Controller of any need to disconnect the power supply or of any reconnection schedule. Close and reopen RTA roads affected by flooding and advise SES The Hills Local Controller.
Notify SES The Hills Local Controller of flood conditions and response needs in the RFS District and. Liaise with SES and arrange for the early release of students whose travel arrangements are likely to be disrupted by flooding and/or road closures. Provide Liaison Officer to SES The Hills Local Supervisor or SES Western Region Headquarters in Sydney as required.
Preparedness
- Maintenance of this Plan
- Floodplain Management
- Development of Flood Intelligence
- Development of Warning Systems
- Public Education
- Training
- Resources
An identification of potential customers of flood warning information at different flood levels (ie who would be affected by floods of different severity). Publicizing this plan and flood-oriented SES activities through local media, including articles in local newspapers about the flood threat and appropriate responses.
Response
Control Arrangements
Start of Response Operations
The Hills Local Emergency Management Officer (LEMO), for transmission to the appropriate council officials and departments, including the mayor, The Hills Shire Council.
Designation of Start Time
Strategies
The preventive movement of people away from areas that will be affected by floods. Minimize disruption to the community by resupplying villages and towns that have become isolated as a result of flooding. Ensure that supplies to property owners are maintained by coordinating the resupply of properties that have become isolated due to flooding.
The impact may vary from sector to sector, so it may be necessary to choose several different strategies and implement them across the entire area of operation. The impact can vary from sector to sector, so several different strategies can be chosen and implemented across the entire area of operation. The strategies available for each sector are explained in detail in Part 6 of the Hawkesbury Nepean Flood Emergency Sub-Plan.
Operations Centres
Operational Management
Sectors covering Cattai Creek catchment, Rouse Hill catchment and Upper Parramatta catchment with Hills LGA. The Gunderman South Sector Commander will operate from a mobile control center in Gunderman (as detailed in the Gosford Local Flood Plan) and will provide a. The Macdonald River sector will be controlled from SES local headquarters The Hills, as it will be the main means of deploying assets by air.
Liaison
All Clear
The appropriate supervisor will also advise on the details of recovery coordination arrangements, cleanup arrangements before evacuees are allowed to return to their homes, and resignation instructions for agencies not required for recovery.
Collating Situational Information
The Regional Headquarters provides information on flooding and its consequences, including in nearby municipal areas (this information is documented in Bulletins and Situation Reports). SES meter readers, RFS staff and other community members provide flood information.
Providing Flood Information
They may be given verbally in response to telephone enquiries, but will normally be included in regional SES flood bulletins. SES The Hills Local Controller provides road condition reports for roads in the SES Sydney West Region Headquarters Road Information area. The Road Information Cell obtains information from NSW Police, the Council and the RTA.
SES Sydney Western Region Headquarters distributes road information to SES units, media outlets and agencies as part of SES Flood Bulletins.
Communication Systems
Preliminary Deployments
Road Control
Traffic Control
Aircraft Management
Assistance for Animals
Stranded Travellers
Affected Communities
Properties along River Road can be isolated when River Road floods at various points. In Level 2 flood operations, the town of Wisemans Ferry will need to be progressively evacuated to an evacuation center at Castle Hill RSL Club. After leaving the Sector, these people will be moved in accordance with the traffic management arrangements (detailed in the Hawkesbury Nepean Flood Emergency Sub-Plan) to the evacuation centre.
Managing Property Protection Operations
Managing Flood Rescue Operations
Managing Evacuation Operations
If the scale of evacuation operations is beyond the capabilities of local resources, control may be escalated to the SES Sydney Western Region Controller. However, the decision to evacuate will normally be made in consultation with the SES Sydney Western Region Operations Controller and the local Emergency Operations Controller. SES will issue an evacuation warning when the intent of an SES Operations Controller is to alert the community of the need to prepare for a possible evacuation.
The SES will issue an Evacuation Order when the intent of the SES Operations Controller is to direct a community to evacuate immediately in response to an imminent threat. Evacuees will be advised to go to the nearest accessible evacuation center or go to the nearest accessible evacuation centre, which may initially be established at the direction of the SES The Hills Local Controller, but managed by Welfare Services as soon as possible.
Managing Resupply Operations
Isolated properties can call their suppliers directly, place their orders through their own social networks or contact the SES. If an isolated household seeks re-provision from the SES and claims to be in, or perceived to be, dire circumstances, he/she should be referred to welfare services for assessment of eligibility. Where financial eligibility criteria are met, Welfare Services will assist with the purchase of essential grocery items.
Welfare Services will deliver essential food items to the loading point designated by SES for transport. Local suppliers will liaise with SES regarding delivery of supply items to the designated loading point. Please note that the flowchart describes the resupply process, but does not include all possible situations and/or outcomes.
If further SES resources are required from other regions, they will be deployed by the SES State Headquarters. Essential service providers must keep the SES Local Controller informed of their status and ongoing ability to provide their services. The functional areas will liaise with the SES Local Controller as per the Local DISPLAN.
Agriculture and Animal Services
However, in Level 2 flood operations, the provisions of the Hawkesbury Nepean Flood Emergency Sub Plan apply.
Communications Services
Energy and Utilities
Engineering Services
Health Services
Transport Services
Welfare Services
Recovery
Recovery Coordination at the Local Level
Recovery Coordination at the District and State Level
This is initially passed on to SEOCON for confirmation at SERCON.
Arrangements for Debriefs / After Action Reviews
The Hawkesbury River basin is one of the largest on the New South Wales coast, covering a total area of 22,000 square kilometers and extending south beyond Goulburn and west to the Great Dividing Range. The upper and middle parts of the Hawkesbury River watershed are home to a number of important water storage dams, the largest of which is the Warragamba Dam, which controls 41%. The main sources of flooding in the Baulkham Hills Shire are the main arm of the Hawkesbury River, which flows through Sackville, and the Colo and MacDonald rivers, which together drain the northernmost portion of the total Hawkesbury River basin.
Tsunamis can also cause flooding on the islands and in other low-lying areas in the mouth of the lower Hawkesbury River, but this flood-producing mechanism is very rare. The wettest part of the year is usually summer, but some of the worst floods seen on the river, including the record flood of 1867, occurred during the winter months. Referring to this table and the previous one, it appears that the 1961 flood at Wisemans Ferry was on the order of the 20% AEP flood.
A scientific estimate of the worst flood possible at a location is the Probable Maximum Flood (PMF). Heavy rain downstream of the dam or over the Colo or MacDonald River in the same event is likely to cause higher flood levels. In the lesser events, the main effect is that the Singleton Rd between Wisemans Ferry and Singletons Mill is cut at several low points, usually only for short periods, and low-lying parts of the Laughtondale and Veeponic Caravan Parks are flooded.
The RTA and SES are advising the Wisemans Ferry School Principal and the Wisemans Ferry Preschool Superintendent of the impending ferry closure. The entire Laughtondale caravan park is under threat as well as a number of dwellings east of Laughtondale and between Singleton Rd and the river. Flooding may also occur in and around low-lying parts of Brooklyn and on islands in the lower Hawkesbury River estuary.
Flooding approaching the severity of the record event of 1867 would inundate the entire Wisemans Ferry Country Retreat and the lower-lying shops and residences of the town. As a result of the flood level predicted by the Bureau of Meteorology for [ location ] on [date/time], State Emergency Services recommends that residents within the designated areas prepare to evacuate within the next [number of] hours. As a result of the flood level predicted by the Bureau of Meteorology for [ location ] on [date/time], the State Emergency Service is instructing residents in the nominated areas to evacuate within the next [number of] hours.
