This report has been prepared following the flooding in the north east of England in early June 2000.
It comprises the following sections:
- Flood causes
- Key aspects of the Agency's response
- The extent to which effects of the floods were mitigated by Easter Floods actions
- Further lessons learned / key recommendations
2.THE IMPACT OF THE FLOODING
Over a three-day period, from the 3rd to the 5th June 2000, the north east of England experienced a flood of unusual severity and extent for the time of year. Weather throughout May had been much wetter than average, so that by the beginning of June the river catchments were already saturated. Throughout the evening of 3rd June, an active weather front tracking slowly north caused very high intensity localised rainfall which affected a number of locations from Newcastle in the north to Castleford in the south.
Just over a thousand properties were flooded, with the principal areas affected being South Church, and West Auckland in County Durham, Neasham in North Yorkshire, and Todmorden and Hebden Bridge in Calderdale. In many catchments the flood was of the order only to be expected every thirty years or so. In particular the River Gaunless in County Durham reached its highest ever recorded level, and is considered to have been a flood only to be expected once every hundred years. At York, the River Ouse reached its highest June level since records began in 1885.
The physical impact of the flooding described above is of course the forerunner of a social impact on people's lives and health. A significant proportion of people flooded in county Durham are yet to return to their homes. Qualitative research into the impact on people's lives and health from stress, stress related illnesses and physical health effects has been commissioned for areas in Calderdale and County Durham. These studies will be carried out by Middlesex University's Flood Hazard Research Centre, who conducted similar studies for the Agency following the Easter Floods of 1998. The research will take place throughout September, and a draft report issued to the Agency in November 2000.
3. FLOOD CAUSES
The principal cause was river channel capacities being overwhelmed by the volume of water running off saturated hillsides and roads, filling the natural floodplains. At one time it is estimated that over one million tonnes of water were falling on the Upper Calder catchment every hour. In many locations, surface water problems and the surcharging of road drains, rather than flooding from the main river channel caused flooding.
The current estimate is that just over a thousand properties were flooded. Only sixty-four of these were as a result of Agency flood defences being overwhelmed. Eight hundred and seventy properties were flooded where no Agency flood defences are currently provided, although schemes to protect some of these properties are at various stages of progression. One hundred and twenty eight properties were affected by floodwater from smaller watercourses on which the Agency has no power to provide flood defences.
Other contributory factors have been suggested, some proved to be relevant, others not:
In the Upper Calder valley, the depth and extent of the flooding was significantly exacerbated by the failure of two non-Agency owned riverside walls. These walls were not built as flood defences, however they have offered an element of flood protection in the past. They form part of a 'patchwork quilt' of individual defences, buildings, channel walls, training walls and garden walls, sometimes only a few metres long. These defence lengths have been subject to a visual inspection by the Agency, and considering these ad hoc collection of defences in the round, they have been assessed as being in 'fair' condition. However, this visual survey regime was not sufficiently detailed to address the structural integrity of the walls.
Local residents are blaming the river works associated with a recent supermarket development, for restricting the flood flow, but these works were designed to provide a net improvement in flood capacity.
Contrary to local opinion, flooding was not caused or exacerbated by the controlled release of water from reservoirs operated by North West Water and Yorkshire Water Services.
The maintenance regimes in place have ensured that the defences generally performed well. However, public perception, expressed at the open meetings at Todmorden, South Church and West Auckland, is that there has been a lack of maintenance in recent years on the Rivers Calder and Gaunless. This has been assessed using the Agency's standard methodology, but will be investigated more rigorously with a view to carrying out more extensive maintenance works as a matter of urgency if this is proved necessary.
4. KEY ASPECTS OF AGENCY RESPONSE
A total of fourteen red, thirty amber and thirty yellow flood warnings were issued, principally via over two and a half thousand calls made by the Automatic Voice Messaging (AVM) system, and the sounding of flood warning sirens in the Upper Calder valley. The areas flooded at South Church and West Auckland are not covered currently with a flood warning service.
It is estimated that Agency flood defences protected over five thousand properties that would otherwise almost certainly have been flooded. Agency defences successfully protected areas such as York, Yarm, Pateley Bridge and Boroughbridge. Agency assistance on the ground in deploying sandbags, assisting with pumping etc., also reduced damage to affected properties. In total, sixty five Agency personnel worked around the clock in shifts manning incident rooms and on-site at the floods, with an additional seventy eight Emergency Workforce staff deployed. In all one thousand four hundred sandbags were put into use with a further eight hundred available on stand-by.
Where flooding did occur, Agency staff assisted emergency services with evacuation, and provided further assistance to clear-up operations.
At Croft, on the River Tees in North Yorkshire, there were operational problems with the closure of a floodgate. A scheme to protect the village, comprising of earth banks and floodgates, has yet to be fully commissioned. Operations staff attended the site to close a gate but found water already flowing through it. The site supervisor assessed that an attempt to close the gate in the circumstances would present an unacceptably high safety risk to Agency staff and decided to leave it open. The flood room was informed and a senior flood response officer was sent to Croft to decide what action to take. On arriving at the site he found that a member of the public had accepted the risk personally and had waded through the water to close the gate.
5. THE EXTENT TO WHICH EFFECTS OF THE FLOODS WERE MITIGATED BY EASTER FLOODS ACTIONS
As a result of actions taken following the Bye Report into the Easter Floods of 1998, significant procedural and organisational changes have been made within the Agency. More than half of the actions taken contributed to an improved response by the Agency and our partners during this particular flood. For example:
- Completion of the first phase of the telemetry works resulted in one new rainfall station being used to monitor this flood.
- A review of flood warning dissemination systems and triggers had been carried out pursuant to an Easter Floods Action. As a result, flood warnings were issued using the most appropriate alert systems. In particular, in the Upper Calder valley the established alert system of sirens had been supplemented with an AVM service. This proved of great benefit, as the sirens were not heard by all those affected. In addition, procedures had been amended to ensure that warnings could be triggered as a result of observed river levels and/or forecast levels. Again, this proved invaluable as warnings were still triggered despite difficulties with the forecasting system.
- A regular documented testing programme for the various flood alert systems helped to ensure these worked successfully during the flood.
- Liaison with local authorities and emergency services was helped as a result of a rigorous regime of checking contact details, an improved understanding of our relative roles and statutory powers, and an ongoing programme of multi-agency major flood incident exercises (three such exercises have been held to date in the North East Region). These actions have moved us closer to 'the seamless and integrated service we are striving for. The availability of Indicative Floodplain Maps to Agency and emergency services' officers contributed to an improved understanding of possible flood risk areas.
- Programmes of regular training of duty staff, through participation in weekly handover sessions and flood exercises, have raised skill and competence levels which helped in the management and response to this flood.
- Public awareness in many areas affected is believed to have been higher as a result of the national and regional campaign of autumn 1999. These campaigns were built upon research as suggested by the Bye Report. The regional campaign, managed by a dedicated Flood Warning Public Awareness officer in the region, included specific events at Neasham and in the Upper Calder valley.
Whilst there have been significant improvements to the Agency's service already, further improvements will be achieved as the organisational changes and structures implemented as a result of the Bye Report bed down.
6. FURTHER LESSONS LEARNED/KEY RECOMMENDATIONS FOR THE FUTURE
The failure of two non-Agency riverside walls during this flood has highlighted a key issue concerning the flood warning service for locations where non-Agency walls provide an element of flood protection. In such locations, the triggers for flood warnings effectively assume structural integrity of defences which have been subject only to a visual (not structural) inspection. It is therefore important that where structural assessments have not been made, flood warning triggers must be reviewed and lowered.
Furthermore, the Agency's policy in respect of the inspection of third party defences will be reviewed by the National Flood Warning Centre, with a view to developing a risk-based approach that would facilitate a prioritised programme of structural surveys. Such surveys are not currently undertaken and resources to complete the work will need to be identified.
The catchment characteristics of the Upper Calder valley mean that it is not possible for the Agency to issue accurate flood warnings with two hour lead times in accordance with our Customer Charter. The forecasting system used was enhanced in 1996 in order to improve the lead time and accuracy of warnings, through the use of weather radar data input to forecasting models. Radar data allows a much improved representation of rainfall in terms of its extent and duration, than is provided by isolated rain gauges. Unfortunately, the communications network via which radar data is received by the Agency failed on 3rd June, so that this data was not available to the forecasting model. The forecasts therefore were able to use rain gauge data only, which did not provide adequate representation of the rainfall. This meant that the forecasts were less accurate than might have been the case had weather radar data been available. Warnings were therefore triggered by observed levels only. This was compounded by the fact that many properties were flooded as a result of surface water and drainage problems, which occurred earlier than the onset of flooding from the River Calder. This led to a perception that the Agency's flood warnings, for flooding from the river were not given with sufficient lead time. It is considered that introduction of the earlier Floodwatch warning stage as part of the revised Flood Warning Codes is likely to be of significant benefit in this respect. However, it must be recognised that the emphasis for action will be on the residents themselves. Options for advancing the flood forecasting system even further through improved use of weather radar and thunderstorm forecasting are being examined. We will determine the maximum lead time we can provide and will publish this to make clear the standard of service offered.
We will renew efforts aimed at educating the public about flood defence schemes. The fact that the schemes provide alleviation from flooding and not complete protection should be emphasised as part of the ongoing public education activity, both nationally and regionally.
We should continue to press at senior and officer-level within local authorities for the production of Major Flood Incident Plans and the testing of these Plans through flood emergency exercises, pursuant to MAFF high level targets.
In accordance with standard procedure, the collection of new data and information about this flood will be used to re-assess the standards of service (for both flood defences and flood warnings) offered to the flood risk areas affected. Where the re-assessed standards are below the target standard
a prioritised programme of improvements and extensions to the service will be made, in accordance with MAFF high level targets.
With rerefence to the areas most severly affected during this flood, the following key actions will be taken:
Consultants will be appointed to carry out a strategic appraisal of the River Gaunless flood risk areas to determine options for technically and economically feasible flood defence works. Draft recommendations will be available by September 2000
A new flood warning service will be introduced by September 2000.
A pre-feasibility study to examine options for reducing flood risk will be carried out. Various local drainage problems are being reviewed with the Highways Agency and the water undertaker
Consultants have been appointed to prepare an Improvement Strategy for the Upper Calder valley. This will identify any technically and economically feasible works that would improve flood protection. A draft strategy will be prepared for October 2000.
A full list of recommended actions will be presented to both the Northumbria and Yorkshire Regional Flood Defence Committees at their next meetings.