COMHAIRLE CONTAE ÁTHA CLIATH THEAS
SOUTH DUBLIN COUNTY COUNCIL

south dublin county council crest

MEETING OF SOUTH DUBLIN COUNTY COUNCIL

Monday, January 11, 2010

MOTION NO.9

MOTION: Councillor E. Coburn

That the manager detail the flood management plan in place for county, how this compares to previous years and to guarantee that flood prevention work will continue.

REPORT:

The Liffey Catchment

Two meetings of the LIFFEY Catchment Flood Risk Assessment and Management (CFRAM) Study Steering Group have been held to date.

The main stakeholders attending the steering group meeting include officials from South Dublin County Council, Fingal County Council, Kildare County Council, Wicklow County Council, Dublin City Council, Office of Public Works and ESB. The OPW are currently carrying out cross sectional surveys of the Liffey and its tributaries.

Summary of Regional Liffey Flood Event of 29/11/09

Most of the Liffey River is controlled by the ESB through its dams at Pollaphuca and Leixlip with the quantity of water per second released through the tailraces regulated by the ESB. The ESB works very closely with Met Eireann and releases extra water in advance of heavy rainfall being forecast so that they have additional storage space at the dams to impound this water and they then release this water after the event thus avoiding property and land downstream of the dams being flooded. There is height storage capacity in the Blessington Lakes and to lesser extent at Leixlip. The ESB also works very closely with Dublin City Council (DCC) as part of the Liffey at its estuary is tidal. DCC had an innovative tidal surge early warning system installed some years ago as part of the Dublin Flood Initiative which was funded by DCC/OPW/EU Interreg. This sophisticated tide surge forecasting is accurate to + or -50mm.

Over the weekend, 21st/22nd November 2009, during the high of the rainfall contolled releases of 70 tonnes per second in pulsed 7 hour bursts were released from Leixlip dam to tie in to the tides in Dublin Bay. Over the weekend, 29th of November 2009, these releases had to be increased to 116 tonnes a second resulting in some flooding of the Strawberry Beds Road near Lucan in the Fingal County Council’s area but no flooding in Lucan Village.

A greater risk of flooding from the Liffey river in Lucan comes from the unregulated Rye Water Stream flowing through Leixlip Village downstream of the dam into the Liffey. During heavy rainfall it is possible to have a greater volume of water coming down the Rye Water than through the regulated dam on the Liffey at Leixlip. It is planned that the OPW will put weirs and gauges on the Rye Water shortly and this information can be relayed back to the ESB so that the Liffey flows can be regulated even more closely.

Since the flooding of Lucan Village and some of its suburbs, Old Forge and Grange Manor Estates, on the 5th and 6th of November 2000 by the Griffeen Stream major flood alleviation works were undertaken by SDCC in Lucan Village and through Griffeen Valley Park right up to the Grand Canal including widening and deepening the river channel, installing new culvert and bridges and lowering weirs and raising walls. This work was completed in 2004 and since then there has been no flooding in the Lucan area from the Griffeen Stream.

All Local Authorities along the Liffey, Kildare, SDCC, Fingal and Dublin City Council plus the Office of PublicWorks (OPW) work closely with the ESB with regard to regulating the flows in the Liffey and if there was a problem which required the deliberate discharge of additional water from either Pollaphuca or Leixlip dams the Local Authorities would be informed in advance so that Public Representatives, residents and businesses could be warned and advised as to the best course of action to undertake and what assistance was available and where. Sandbags would also be issued to potential vulnerable areas.  

During the high rainfall event of 29/11/09, which impacted on the whole of the Liffey Catchment, communication was ongoing throughout the day between South Dublin County Council’s flood management team and the other Liffey CFRAMS stakeholders. The steering group will use the experience gained from this event to inform the ongoing Liffey Study.

Lucan has been identified as an Area of Potential Significant Risk (ASPR) for additional focus. Nearest other ASPRs are Leixlip in Kildare and Chapelizod in Dublin City. Dublin City Council are proposing a new weir at Lucan for flow measurement. The Camac, Poddle and Griffeen are part of this overall study.

 

The Dodder Catchment

In late 2005/early 2006 the three local authorities in whose functional areas the river Dodder flows i.e. South Dublin County Council (SDCC), Dun Laoghaire Rathdown County Council(DLRCC) and Dublin City Council (DCC) agreed that a study of the river would be commissioned in order to provide a comprehensive report on the Flood Risk Assessment and Management of the river. The Office of Public Works (OPW) is funding the study as it forms part of the national Catchment Flood Risk Assessment and Management Studies (CFRAMS). Dublin City Council is the Contracting Authority on behalf of the three local authorities.  Following the public tendering procedure in early 2006 Dublin City Council appointed consultants/service providers, R.P.S., to carry out the Risk Assessment and Management Report. The major stakeholders, DCC, OPW, SDCC, DLRCC and RPS meet at Steering Group level every three months to review the progress of the contract.  The final plan will require the agreement of all three Councils and the OPW.

The core purpose of this study was to assess the spatial extent and degree of flood hazard and risk within the Dodder catchment, to examine future pressures that could impact on that risk, and to develop a long-term strategy for managing the risk that is economically, socially and environmentally sustainable.

The Report will include measures for the development of a robust model representing the hydrological and hydraulic characteristics of the River Dodder catchment, such a model will provide for the mapping of the flood risk.  Using model output the technical and economic merit of various options for flood management, taking account of current and future land developments, will be presented within the report.

To achieve this aim the following study objectives have been identified:

The main tributaries of the Dodder River are included in the above Risk Assessment and Management Report viz. the Whitechurch, Owendoher and the Tallaght streams.

In June 2008, the consultants issued a strategic environmental assessment (SEA) scoping report on the River Dodder Catchment Flood Risk Management Plan.  This Report is available to download on the Dublin City Council website: www.dublincity.ie/waterwasteenvironment/pages/riverdoddercatchmentfloodriskassessmentmanagementstudy.aspx  Comments can be sent to the above website or doddersea@rpsgroup.com

The final SEA statement will:

Further plans for the Dodder River Risk Assessment and Management Strategy include public information days on the flood risk management, a draft CFRAMS and Environmental Report consultation and a final Strategic Environmental Assessment (SEA) statement.

R.P.S., were also asked to produce an interim modelling report on the Whitechurch River, a tributary of the Dodder, as a result of serious flooding experienced  in the catchment on 22 June 2007. The  Whitechurch River Interim Modelling Report issued from R.P.S. in July, 2008 with recommendations on reducing the flood risks along the Whitechurch River. Following the publication of the report, South Dublin County Council in conjunction with Whitechurch National School completed an emergency culvert upgrade on the Whitechurch Stream at the entrance to the school to prevent further flooding and property damage in the area. The cost of these work was approx. €150,000.

Floods Directive

Directive 2007/60/EC on the assessment and management of flood risks entered into force on 26 November 2007. This Directive now requires Member States to assess if all water courses and coast lines are at risk from flooding, to map the flood extent and assets and humans at risk in these areas and to take adequate and coordinated measures to reduce this flood risk.  This Directive also reinforces the rights of the public to access this information and to have a say in the planning process.

The Directive was proposed by the European Commission on 18/01/2006, and was finally published in the Official Journal on 6 November 2007. Its aim is to reduce and manage the risks that floods pose to human health, the environment, cultural heritage and economic activity. The Directive requires Member States to first carry out a preliminary assessment by 2011 to identify the river basins and associated coastal areas at risk of flooding. For such zones they would then need to draw up flood risk maps by 2013 and establish flood risk management plans focused on prevention, protection and preparedness by 2015. The Directive applies to inland waters as well as all coastal waters across the whole territory of the EU.

The Directive is carried out in coordination with the Water Framework Directive, notably by flood risk management plans and river basin management plans being coordinated, and through coordination of the public participation procedures in the preparation of these plans. All assessments, maps and plans prepared shall be made available to the public.

Member States shall furthermore coordinate their flood risk management practices in shared river basins, including with third counties, and shall in solidarity not undertake measures that would increase the flood risk in neighbouring countries. Member States shall take into consideration long term developments, including climate change, as well as sustainable land use practices in the flood risk management cycle addressed in this Directive.”

Draft Planning System and Flood Risk Management Guidelines

The Ministers published new Draft Planning System and Flood Risk Management Guidelines for Public Consultation in September which are aimed at ensuring a more consistent, rigorous and systematic approach to fully incorporate flood risk assessment and management into the planning system.

The implementation and coordination of WFD policies and Flood Risk policies is ongoing