18 August 2009

Some reflections on the Typhoon Morakot landslide disaster in Taiwan

Posted by Dave Petley

For landslide scientists Taiwan has an almost mythical status, effectively being the nearest thing to a landslide laboratory. To my great benefit I have been able to work on landslides in Taiwan since 1991. As well as being a country of great beauty (there are good reasons why the Portuguese named it Ilha Formasa – Beautiful Island – in 1544), the combination of high rates of tectonic uplift, weak rocks, steep slopes, frequent earthquakes and extreme rainfall events renders the landscape highly susceptible to landslides and debris flows. Indeed, Taiwan has almost every type of landslide, although as an aside the number of known ancient rock avalanches remains surprisingly low given the prevailing conditions.

Of course the reason why Taiwan is of interest to landslide scientists is also the reason why it can be a challenging place in which to live. When the World Bank reported in 2005 on its “Disaster Hotspots” study it noted that “Taiwan may be the place on Earth most vulnerable to natural hazards, with 73 percent of its land and population exposed to three or more hazards”. The last great disaster there, the Chi-Chi Earthquake, which happened almost exactly a decade ago, was a wake-up call to the hazards that mountain communities face in Taiwan. I think that a great deal has been achieved in Taiwan since this event, but the Typhoon Morakot disaster shows that there is so much more to do.

Inevitably, and frankly understandably, there is now a great deal of concern in Taiwan about the viability of its mountain communities. The issues are complex – many mountain villages are inhabited by indigenous populations that have strong ancestral links to their land. In other areas the communities were settled by retired soldiers who came to Taiwan with Chiang Kai-Shek in 1949. Both sets of mountain dwellers are poor, but they are often passionate in their desire to remain in their rural communities. There are high stakes here, with the possibility of a new wave of enviornmentally-damaging engineering works in the mountain areas.

Unfortunately, in Taiwan much of the development in mountain areas has been undertaken without fully considering the ways in which humans and natural processes interact in this sort of environment. In many cases this is quite understandable – the processes are so dynamic that our understanding of them is poor – but the consequences are tragic. The race of build mountain hotels is perhaps the most obvious case – as the typhoon so clearly showed – but there are many other examples. As roads, hydroelectric schemes, fruit farms, recreation areas and many other developments cause extensive environmental degradation, the landscape is responding with increased rates of erosion, mainly in the form of landslides, debris flows and floods, that puts the population at risk.

I should stress that I am not calling for a moratorium on development in the mountains in Taiwan, and nor am I advocating that the mountain populations are relocated. I do believe that development, including road construction and the building of hydroelectric power schemes, is viable. In addition, I also believe that it is possible for people to live, relax and work in the mountains with tolerable levels of risk, although as Shiaolin showed some of the existing communities are built in highly dangerous sites. I do think that some activities in the mountains probably cause too much environmental damage – in the highland areas fruit farming appears to me to be causing extreme levels of degradation for example, and the construction of “hot spring resorts” is often insensitive and poorly planned – but most mountain communities should be helped to change their way of life, not to be forced into relocating.

So here is my suggested manifesto for reducing (but not eliminating) the risk from landslides in Taiwan:

  • Develop and implement a comprehensive national plan for managing slopes, covering design standards, training, land use management, emergency response, etc. This effectively mirrors the very successful slope management programme developed in Hong Kong and, more recently, in Malaysia.
  • Develop a comprehensive research programme to understand the natural processes occurring in the mountain areas of Taiwan. The National Environmental Monitoring Center being proposed by National Taiwan University seems to me to be an essential element of this that could also provide world class science outputs. Operate in the network in a manner similar to GEONET in New Zealand, having both science and public understanding ofd science benefits, Ensure that the outcomes of the research are fed back into the planning and management process.
  • Undertake a properly coordinated and sensitive programme to evaluate the safety of all upland communities. Where risk is found to be high, identify the best mechanism to bring this to a tolerable level, through combination of well-designed engineering works, education programmes, warning systems and, in extremis, relocation to nearby safe sites. This will need to be accompanied by a programme to determine the level of tolerable risk in this environment, and to ensure that there is an understanding that the aim is not to elimate risk, but rather to manage it.
  • Constitute a national disaster management agency to coordinate disaster risk reduction and disaster response.

Templates for all of the above exist in other countries. To achieve this will take considerable political will, and both resource and time. However, management of risk is achievable without forced relocations or catastrophic environmental damage.