There was moderate to high reported awareness of the MetService Heavy Rain Warnings that had been issued prior to the Weather Bomb event. This ranged from 81 % in the low impact Coromandel area to 46 % in South Waikato (Table 6).
MetService issues Heavy Rain and other Warnings according to specific criteria (see Appendix 1); territorial authorities decide on the basis of this and other information if flood and other warnings are necessary within their jurisdiction. Along the western Coromandel the catchments are small and have short response times, and no flood warning system exists. To explore the public's perception of warnings and see if people make any link between the Heavy Rain Warning and the subsequent flooding, two questions were asked (Tables 7 and 8). Only a minority reported receiving a specific warning of the forthcoming flood itself (the highest being 32 % in the high impact area) (Table 7). Of those who received a warning, a range of sources were reported, with MetService and the media (TV and radio) being the most common in all areas (Table 8). The largest percentage of warned respondents in the South Waikato and Coromandel low impact areas received their warning more than six hours prior to the flooding. The highest percentage of bach owners were warned of possible flooding one to six hours ahead, but in the Coromandel high impact area people had less than 10 minutes warning before being flooded (Table 7).
The questions asked in this survey do not fully address what is a complex issue and further work is need to explore the links (real or perceived) between weather and flood warnings, the public's understanding of them and how best to improve the effectiveness of both. The need for improved tools for responding to floods in New Zealand has also been identified in recent research on the Waikanae floodplain (Johnston et al. 2002).
Some residents suggested that they did not fully realise the potential impacts of the forecast heavy rain. One resident stated (Appendix 11) "We took no special action as we were not warned the 'weather bomb' would be any threat - we just thought we would have heavy rain. No way did we realise how much & what impact it would have". One TCDC staff member suggested that they get a lot of Severe Weather Warnings and didn't necessarily expect this to be different to any of the others (i.e. expect it to cause flooding). This raises the possibility of 'warning saturation' due to regular warnings reducing the impact of, and response to, individual warnings. The effects of 'warning saturation' require further research.
There is considerable research pointing to the value of simple alert schemes to help individuals, organisations and communities responding to developing crises (Mileti, 1999, Sorensen, 2000, Hander, 2002). A number of alert schemes have been developed in New Zealand for a range of hazards, notably drought, rural fire and volcanic hazards. Other overseas schemes have also been developed for tornado, hurricanes and recently terrorism in the USA. Recent flood events in New Zealand and the USA have lead a number of groups to raise the idea of developing alert level scheme to provide a tool for managing local flood events. In the USA Congress has ordered the National Oceanic and Atmospheric Administration (NOAA), through the United States Weather Research Program to develop an index to assist in this effort (Natural Hazards Observer 2002). On October 2002, the Inland Flood Forecasting and Warning System Act of 2002 (Public Law 107-253) was signed into law to provide for research, training, and outreach activities relating to improving inland flood forecasting and awareness. Under the legislation NOAA is required to develop, test, and deploy a new flood warning index to give the public and emergency management officials more detailed, understandable, and accurate information about the risks and dangers posed by expected floods.
Despite the above suggestions it is still not clear, given the short flood response time in the catchments and the lack of flood warnings systems how a system would work but it is an issue worth exploring. Environment Waikato does operate an automated flood warning system for the region in other, larger catchment, watercourses. Even if the capacity to disseminate a flood warning alert existed, possibly following an alert scheme, the MetService may not have been able to forecast the full magnitude of this event compared to other Heavy Rain Warning events.