Taiwan faces many natural hazards, especially typhoons, earthquakes, and floods and landslides that are linked with typhoons.
According to Taiwan’s Central Weather Bureau (CWB), 408 typhoons in total, i.e. an average of 3.6 typhoons a year, had struck Taiwan from 1898 to 2010. And the UN Intergovernmental Panel on Climate Change predicted that although the number of typhoons likely to hit Taiwan in the years to come may not increase significantly, but their magnitude or intensity will most likely rise because of global warming and climate change.
Typhoons have destroyed human, social, and physical capital in Taiwan, and they have derailed national social and economic development. In the past 40 years, annual direct damages brought by typhoons and floods amounted to as much as NT$17.4 billion (US$600 million) equaling to 0.33% of the national GNP. And indirect and secondary impacts further increase this cost. In addition to this significant socio-economic cost, there are also substantial adverse environmental impacts.
In order to minimize the risk of typhoons and reduce and mitigate their effects, an operational typhoon forecasting and warning system is crucial. The precision prediction of the path and intensity of typhoon, rainfall distributions at landfall, etc. set the foundation for the effective early warning. And the successful application of early warning not only renders the most practical pre-event measure for avoiding the creation of disaster-prone conditions, but also facilitates the resilience in the stricken areas.
To advance the development of critical technologies for accurate predictions of typhoons and floods, the NARL, with the support of National Science Council, has recently instituted Taiwan Typhoon and Flood Research Institute (TTFRI). And to accomplish its mission, the NARL-TTFRI is partnering with the academia, CWB, the Water Resources Agency (WRA) of the Ministry of Economic Affairs, the Soil and Water Conservation Bureau (SWCB) of the Council of Agriculture, and the NARL’s National Science and Technology Center for Disaster Reduction (NCDR) and National Center for High-performance Computing (NCHC). Currently, the NARL-TTFRI is developing four core technologies including numerical weather modeling (ensemble forecast), quantitative precipitation estimate/forecast techniques, hydrological modeling (coupled with rainfall model), as well as integrated atmospheric and hydrologic observation techniques. These technologies are to improve forecast capabilities for typhoon and flood events under the complex terrain of Taiwan, and to maximize the efficacy of early warning systems for these weather hazards.
Most of the typhoon-incurred disasters are often caused by massive rainfall brought along with landfalling typhoons which could result in flash flooding, landslides and debris flows. In this connection, accurate forecasts and warnings on tropical cyclone rainfall will play an important role for disaster prevention and preparedness. And this makes quantitative precipitation estimates/forecasts imperative. Prior to the official launching of the NARL-TTFRI, its scientists, in collaboration with the NARL’s NCDR and NCHC, and CWB, have conducted the typhoon quantitative precipitation ensemble forecast experiment. The purpose of this experiment was to improve typhoon precipitation forecast techniques. And the results show that the ensemble forecast significantly improved the efficacy and accuracy of the typhoon precipitation forecast.
Moreover, the prediction of the rainfall distribution in Taiwan could be assessed as early as two to three days prior to the typhoon's arrival on land. Furthermore, quantitative precipitation data, when integrated with hydro-meteorological simulations, can predict river stage and flooding in vulnerable areas, serving the needs for preventive evacuation and disaster prevention operations.
To further improve forecasts and warnings for hazardous weather, the NARL-TTFRI plans to install a transportable polarimetric radar that gives information on the size, shape, and ice density of cloud and precipitation particles. Also the Institute is establishing an experimental river basin that gauges hydrological processes and provides information on real-time flood simulations.
By integrating with short-term computer forecast models, the obtained information can be used to extrapolate to precision 3-hour precipitation predictions. Equipped with these up-to-date equipment and technologies, the NARL-TTFRI is in the right position to provide real-time precipitation forecasts to CWB, WRA, SWCB, NCDR and other government authorities in support of emergency response operations.
