KNOWING WHEN TO GET THEM OUT - IMPROVING FLOOD EVACUATION PLANNING THROUGH FLOOD MODELLING AND STAKEHOLDER INVOLVEMENT

T Anderson1, M Stubbs2, K McAndrew1

1 , NSW 2 State Emergency Service, NSW

Abstract

Floods are not new to Grafton, nor to the Clarence River. But the approach to planning and responding to floods has changed significantly in recent years. This paper discusses these changes, particularly how these changes have already and will continue to result in improved flood management and security for the City of Grafton. Specific reference will be made to the different approach taken in the 2013 flood compared to other recent flood events like in 2001 and 2009.

In 2012 Council’s consultants completed a levee overtopping assessment for Grafton. The objectives of the assessment were to identify the locations where the levee is likely to initially overtop, evaluate the flood risk within Grafton following overtopping, provide detailed emergency response information for levee overtopping events, and assess potential measures which may reduce the flood risks within Grafton.

On the 29th of January 2013, the Bureau of Meteorology (BOM) forecast flood levels at the Prince St gauge in Grafton would reach 8.1m, the highest recording since installation of the river gauge. The recently completed flood modelling suggested that a flood of that level would result in minor overtopping of parts of the Grafton levee, and levels over this reach had the potential to inundate up to 1/3 of Grafton, being over 900 properties.

This BOM prediction proved quite accurate, with the flood level in the Clarence River reaching 8.08m. But in a rare good news story coming out of the January 2013 floods, the planning foresight by Clarence Valley Council, accurate flood prediction by the Bureau of Meteorology, accurate flood modelling by consultants, and careful flood evacuation planning by the NSW SES all combined so that no unnecessary evacuations occurred. This event demonstrated the benefits of flood modelling and stakeholder involvement in flood planning and response.

Key Words:

Floods, evacuation, Clarence River, Flood Modelling, Stakeholder Consultation, Grafton.

Introduction

The Clarence River is called the ‘big river’ city somewhat takes in its stride as the rains and this is for good reason. The Clarence’s fall. Generally Grafton is not affected by catchment is a huge 22,716 km2 and mainstream flooding from local rainfall; rather stretches from the Queensland border to the its flooding is triggered from weather events Doughboy Range in the south – some 250 that occur a considerable distance away. km. The river itself is greater than 430km in Since flood records commenced in 1839, length with 10 rivers flowing into it. Grafton has been subject to over 120 floods - the highest being in January 2013 at 8.08m. Flooding is something that is a common In Grafton the most important gauge for occurrence in Grafton and something that the recording river height is the Prince Street gauge. See Figure 1.

Figure 1. Historic Flood Peak Heights at Grafton since 1839 (2013 event highlighted in red)

Grafton and South Grafton are currently Evacuation routines and flood procedures of protected by a series of levees that, in Grafton have been refined as its flood plans addition to naturally high ground and an have been reviewed, however up until the elevated railway line, surround the town development of the Grafton Annexure of the (Huxley and Beaman, 2014). The levee Clarence Valley Local Flood Plan (2012), system has evolved progressively over time hereafter referred to as ‘the 2012 Plan’ the from 1890 in response to previous floods in evacuation priorities and procedures did not the region (Huxley and Beaman, 2014). have any ‘buy in’ from the community. It was These constant augmentations have meant after the 2001 and 2009 flood events that it that there is no overall master design of the was realised that ‘participation’ in the levee system. evacuation of the city was low. Despite the significant height of the 2001 event, Pfister With significant improvements in technology (2001) acknowledges that the evacuation did and with major studies and modelling not proceed optimally and less than 10% of undertaken across the catchment, the the 12,000 residents of the flood prone areas forecast accuracy of an event is now able to left the city during the 9 hour evacuation be rather precise and hence allows for period. detailed evacuation planning. Current event forecasting and subsequent evacuation is It was following the 2001 flood event that the much different to that which is described by NSW SES started to seriously analyse what the Clarence River Historical Society (2011) had occurred so that improvements could be of days gone by where the forecast depended made for the future. Community view was upon telegrams being received from the sought, Grafton participated in a large study Copmanhurst Post Office. It is stated that regarding flood perception, risk and warning when the water level had reached the across 4 Australian towns. Past research and dispatching desk at Copmanhurst, papers have focussed on the problems of communications stopped and business getting people to follow the SES evacuation people in Grafton starting packing up goods warnings (see Pfister 2001, Becker et al beyond flood level. 2007, Molino et al 2011). But these past papers have not critically examined the SES’s Whilst having data regarding the thoughts flood plan arrangements for the Grafton area. and movement of the town’s people, it took a Important inputs into flood plans are essential few more years for good flood modelling to for the plans to be effective. become available, which combined led to the development of the integrated and improved 2012 Plan.

Figure 2. Locality Map - Grafton and Surrounding areas Digital Terrain Model

Before the 2012 Plan

Flood Plans are traditionally written with the  Sectorisation of Evacuation Warnings – best information available at the time. As there was no sectorisation of Grafton, better information has become available, the meaning that all properties were 2012 Plan is significantly different from SES evacuated at once rather than in stages. evacuation plans in the past.  Local Mass Evacuation Centres – there were no large scale evacuation centres Previous flood plans (e.g. Grafton City Local locally based. Flood Plan, 2001) for Grafton have had the  Level of Flood Protection – former plans below general evacuation strategies: were based on the commonly held belief in Grafton that the levee provided a 1%  Evacuation Direction – The evacuation AEP level of protection. strategy in 1996 was to direct people  Flood Impacts on Critical Infrastructure – north of Grafton to a higher ground these impacts were unknown and locality called ‘Junction Hill’. This strategy undocumented. There was no changed in 2001 and 2009, where information about the Grafton Hospital, evacuees were transported to Coffs electricity, water, or sewer infrastructure. Harbour, a city approximately 80kms to the south of Grafton. The 2012 Plan  Trigger Heights – up until the 2012 Plan there was one single trigger height for The 2012 Plan was produced in line with the the evacuation of Grafton. This trigger 5 yearly review structure, required by the height was 7.5m (7.8m less 0.3m NSW SES, as part of the legislative freeboard). requirements of the State Emergency Service Act (1989). This plan was produced following AEP levee as had been previously significant changes in the philosophy and believed by much of the Grafton methodology in local emergency community. management practices. The inputs to inform  Informing appropriate trigger heights for the 2012 Plan included data obtained from evacuation. This is essential for a leveed flood modelling, stakeholder consultation and city like Grafton. Until this information observations from previous observations. was obtained there had been great uncertainty in the community about when Flood Modelling Inputs the levees will actually overtop. Some It is difficult to have an effective flood plan believed it was 8.00m, others thought without good technical engineering or 8.23m. There had been no real test, and modelling information and improvements in as there was no overall levee design this technology were a corner-stone to the current was an unknown. Grafton residents have arrangements prescribed in the 2012 Plan. in the past viewed the SES’s triggers The previous flood plans in Grafton have not heights as low, causing “unnecessary” had this and as such been difficult to evacuations and have chosen to delay implement. action until the last moment.  Detailing which areas of Grafton flooded Over the years there has been much earlier by levee overtopping, allowing for confusion regarding the overtopping height staged evacuations. This meant that and impacts of the Grafton and South Grafton depending on the predicated flood peak, levees. In response to the uncertainty, the SES now had the opportunity to limit Council engaged a hydraulic modelling the evacuation warnings to areas consultant (BMT WBM, 2011) to prepare impacted by a 5% AEP flood (e.g. as per several reports under a collective project title Figure 3) and perhaps only door-knock of “Grafton and Maclean Flood Levee small number of properties. In the event Overtopping: Hydraulic Assessment (2011), of a 100 year flood, the SES could now hereafter referred to as ‘the Study’. sequence evacuations meaning some areas of Ryan Street (South Grafton) The model used in the Study was built based would require evacuation prior to some on the best information currently available areas of North Grafton. (e.g. LiDAR data, recent levee height survey  Listing the theoretical times inundation data and historical river flow rating curves). would reach certain areas, which allowed The modelling in the Study was intended to the SES to get a good idea of times need be used by a variety of stakeholders for a to undertake evacuations. The report range of purposes (e.g. planning purposes, provided an assessment of critical capital works purposes and evacuation evacuation routes (e.g. Fitzroy Street, purposes). As evacuation is the focus of this , Bent/Ryan paper only this area will be discussed. The intersection, North Coast Railway), and Study was required to provide Council and provided detail on how long after levee SES with information specifically for overtopping the floodwater will reach a emergency management purposes, including depth of 100mm over roads. information about evacuation route closures  Provided flood information for the Grafton (depths and timings) and significant Base Hospital, Grafton’s most vulnerable community resources such as the Grafton facility, explaining how certain floods Base Hospital. impact the Hospital. For example, the over floor inundation timings, with The production of the Study contributed references to the Prince Street gauge significantly to the production of the revised and the final depths of water expected in 2012 Plan. In brief, the new modelling the hospital in certain design floods. This provided significant benefits for evacuation allow for the SES and NSW Health to planning, including: undertake an informed risk assessment before attempting patient relocation prior  Clarifying Grafton’s flood interval level of to or during flood events. protection – a 5% AEP levee, not a 1%

Figure 3. 5% AEP Flood Depth Grafton, note, minor overtopping of levees in South East Corner of Grafton (BMT WBM, 2011)

Stakeholder Consultation and Observations from Previous Floods Grafton’s levee and flooding situation is complex – and it must be emphasised the  The SES door knock was very importance of stakeholder collaboration in determined, and there appeared to be no solving complex situations. The 2012 Plan is delineation of ‘low- lying’ areas i.e. most a result of numerous stakeholder inputs. vulnerable areas.  For evacuations Grafton should be Significant flood events were experienced in divided into low, moderate and high risk the Clarence Valley in 2009 and 2011. As the levels and commence with the highest community is the largest stakeholder in risk. floods, community focus groups were  There should be ongoing dialogue conducted following the floods which offered between community, the NSW SES, some very important analysis of what Bureau of Meteorology, NSW Police and happened in the event at the coal face and the local Clarence Valley Council to views on where improvements could be better prepare the district and improve made. Example of some focus group warnings and response. comments (SES Focus Group, 2009):

In the formation of the 2012 Plan, a Working and predictions of 8.2m evacuation Group was established consisting of Clarence orders for the remaining low-lying Valley Council members, Emergency Service areas of Grafton. Agencies (LEMC), Flood Engineers, NSW  Sectorisation of Evacuation Warnings SES State HQ planners, Local SES – this was considered essential, was Controller, and Flood Consultants. This group desired by the community and made met in April 2011 setting agreed triggers possible by flood modelling. The 2012 informed by modelling that had previously Plan schedules evacuations using the been the cause of considerable confusion for order of Sector A, Sector B, Sector C, emergency management personnel and and finally Sector D. contention for the community. This provided  Local Mass Evacuation Centres – it more realistic heights for commencement of was deemed essential to have a evacuations. locally based large scale evacuation centres. The 2012 Plan nominated The 2009 and 2011 floods allowed for the assembly area is the South Grafton collection of enhanced flood intelligence. The High School Auditorium. This large lessons learnt from previous events provided facility can be used as an assembly opportunities so past mistakes are not point in the short term, but could also continued into the future. The opportunity to double as an evacuation centre enact parts of the earlier plan and the revision should the need arise. of procedures was invaluable. The general  Flood Impacts on Critical evacuation strategies discussed earlier were Infrastructure – knowing these able to be critiqued: impacts was deemed essential to inform evacuation decision. As such  Evacuation Direction: The problem these impacts were revealed through with the Junction Hill strategy is that it stakeholder consultation and flood is likely to be isolated during a major modelling. The 2012 Plan provided flood event and also there is no information on sewer, drinking water, potential evacuation centre located in electricity and communications. The Junction Hill of sufficient capacity to modelling stated that the Grafton house the evacuated residents. hospital will only be inundated in Additionally, the problem with the floods that exceed 9.0m (a rarer than Coffs Harbour strategy is that the SES the 0.1% AEP flood). obtained feedback that evacuees  Notification of Warnings – January were more likely to move to an 2011 was the first occasion where evacuation centre if it was locally emergency alert telecommunications based. People were not happy moving technology was ultilised. Community to locations 80km away from their feedback enabled determination of homes. The 2012 Plan states the better messaging for the future. priorities of self-evacuation to friends/family outside of the impact The 2013 Flood Event area or to an appropriate facility located on high ground in South The flood event in January 2013 provided an Grafton. occasion to test the changes implemented in  Trigger Heights – clearly the existing the plan and the benefits they provided to single trigger height was too low, as emergency response and community. floods had reached that level without any inundation of Grafton. It was On the 29th of January 2013, the BOM realized that multiple triggers would forecast flood levels at the Prince St gauge be beneficial. The 2012 Plan states would reach 8.1m. At this flood level the that prediction of floods to reach or modelling predicted minor overtopping of exceed 7.8m would result in targeted parts of the levee and under the 2012 Plan, evacuation warnings of Sector A, 7.9- the targeted evacuation of Section A was 8.0m floods evacuation order for undertaken. The BOM prediction proved Sector A and warning for other areas, quite accurate, with the flood level reaching 8.08m. The flood modelling proved accurate either in terms of inputs to it or outputs in terms of defining the area which would be from it. inundated from the minor overtopping.  The SES has found it useful to maintain effective liaison with councils This new refined 2012 Plan allowed the by, for example, keeping council community to access specific data from either engineers briefed on the planning the NSW SES or Clarence Valley Council work and presenting papers at website, on their local area, detailing all conferences on flood themes. trigger alert mechanisms which will be used  Keep the plans alive. A failing of much and the evacuation routes to the established emergency management planning is Assembly Areas. The Clarence Valley Flood that too many plans are allowed to Plan was also supported by Flood Safe gather dust after they have been Guides which are provided to community written. members prior to operational times, and  Response organisations must be mirrors the information held by the Incident encouraged to keep their plans under Controller but in a simple, easily review so as to recognise changes in understandable format. the flood environment (which will alter the nature of the flood problem) or The operational sectoring of the high risk changes in the community (which may areas into fourteen response components alter the required management allowed the operational planners quick arrangements outlined in the access to important information needed for document). enacting the evacuation of residents through various alert systems and relocation to pre- Conclusion established assembly areas, through a road network system that should not be affected This paper described recent changes to the by closures or inundation. Timeframes Grafton Annexure of the Clarence Valley allowed for the issuing of warnings via, radio, Local Flood Plan and how these changes television, social media and emergency alert came about. This paper does not claim that mechanisms nominated in the sectors. the 2012 Plan is perfect and that it will not be updated again in the future. There is no such The success of the 2013 flood in Grafton and thing as a perfect plan, and with changes the good management practices that were such as a new Grafton Bridge a major followed and put into action resulted from all highway bypass, and technology of the above stakeholder contributors. During developments the 2012 Plan will certainly this event warning orders were issued to high need to be updated again in the near future. risk areas rather than all residents and a new evacuation centre, outside of the flood zone, was implemented. Other key indicators of the success of the 2013 event was the fact that After Action Reviews revealed very little need to change any aspect of the 2012 Plan, there was only positive media coverage of the SES’s performance in the event, and the Grafton community seemed to have good ‘buy-in’ of the 2012 Plan.

Lessons from the Experience

The lessons from this project are similar to the lessons noted in Keys (1995/96):

 Develop networks to support the planning activity. Emergency planning cannot be carried out in isolation, References Molino, S., Dufty, N., Crapper, G., and Becker, J., Coomer, M.A., Johnston, D., Karwaj, A. 2011. Are Warnings Working? Ronan, K., 2007. GNS Science Report Achievements and Challenges in Getting 2008/31 Flood risk perceptions, education Communities to Respond. Accessed online: and warning in four communities in New floods.org.au/wp- South Wales, Australia: Data report for a content/.../Thu_MOLINO_Are-Warnings- follow-up questionnaire, September 2007 Working.pdf

BMT WBM. 2011. Grafton and Maclean Flood NSW State Emergency Service. Grafton City Levee Overtopping: Hydraulic Assessment. Local Flood Plan. A Sub-Plan of the Grafton Later complemented by further reports titled Local Disaster Plan (Displan) .October 2001 ‘Lower Clarence Flood Model Update (2013) edition. and Grafton, South Grafton and Maclean Emergency Management Report (2014). NSW State Emergency Service. 2009. Grafton Community Focus Group. Prepared Clarence River Historical Society Inc – When as part of the Clarence Nambucca SES After the rains come down and the floods come up Action Review. – Grafton Floods to 2011. NSW State Emergency Service. Clarence Huxley, C. and Beaman, F. 2014. Additional Valley Local Flood Plan. A Sub-Plan of the Crossing of the Clarence River at Grafton: Clarence Valley Local Disaster Plan Flood Impact, Levee Upgrade, and Structural (DISPLAN). June 2012. Considerations. 5th International Symposium on Hydraulic Structures (Brisbane, Australia, Pfister, N., 2001. Community Response to 25-27 June 2014). Hydraulic Structures and Flood Evacuation Warnings: The Case of an Society: Engineering Challenges and Evacuation from Grafton, March 2001, NSW Extremes. State Emergency Service.

Keys, C. 1995/96. Planning for Floods in . The Australian Journal of Emergency Management. Vol.10 No.4 Author Biographies and Photographs

Troy Anderson – [email protected]

Troy is the Director (Works & Civil) at Clarence Valley Council. Whilst yet to experience flooding of the Clarence, Troy is involved with floodplain management and planning for the valley. Troy played key roles in the flood clean-up and reconstruction of Ipswich, Queensland, following the 2011 and 2013 flooding events.

Michael Stubbs - [email protected]

Michael is the Deputy Region Controller at NSW SES - Clarence Nambucca Region. Michael was the Level 2 Incident Controller during the 2013 Clarence River record flood and has been operational decision-maker in other major Clarence Valley floods. Michael coordinated the development of the Clarence Valley Local Flood Plan.

Kieran McAndrew – [email protected]

Kieran is employed by the Clarence Valley Council in two distinct roles – Water Cycle Engineer and Emergency Management Officer. In the emergency management role, Kieran assists emergency agencies with planning, and provides operational support to the NSW Police Controller during multi-agency emergencies, such as the 2013 Grafton flood of record.