Taiwan's rivers with the period of 3-5 years suffer from the massive flood and result in significant river-bed changes. On the other hand, due to climate change in recent years, significant changes in rainfall characteristics and rising rate of the flood stage can be seen. Therefore, the Water Resources Agency (WRA) collects hydrological events of this year to assess the suitability of the river warning stage, as the reference of the river warning stage announcement in the next year.
Establishment of warning stage has its basic assumptions and limitations. As natural and human-induced environment change, it will result in the question of applicability of existing warning stage. Therefore, revise the warning stage timely can conform to the demand of flood prevention. This year project results are summarized as follows
1. In the existing warning stage stations, Soulik, Trami, Kong-rey, Usagi, Fitow typhoons and 0830 heavy rain etc. hydrological event data were used to review, calculate and check the warning stage of the central authority’s river applicable situations. According to the river warning stage analysis results are shown in summary Table 1. It can be served as the reference to the river warning stage next year. In addition, we also added 10 sets river warning stages. The results are also listed in summary Table 1.
2. In the warning stage of the central authority’s drainage, hydrological event data during this year's flood period were used to review, calculate and check the drainage warning stage applicable situations. According to the measurement data and the drainage warning stage analysis results of this year, the 1st degree warning stages are still applicable, and the relevant results and data are described in Chapter 4.
3. We use the SOBEK hydrologic and hydraulic models that have passed calibration and validation processes. Through WRA’s working group, the outputs of this project can be connected to the FEWS-TAIWAN forecasting platform. The forecasting platform can be used in flood forecasting during the next year.
4. To achieve the relevant technology transfer of review and establishment of warning stage for central authority’s river, we prepared the operation manual of hydrologic and hydraulic models for the 1st , 5th , 6th , 8th and 10th River Management Office of WRA. One or two engineers of above units were trained model installation and operation of the hydrologic and hydraulic model to achieve the purpose of technology transfer.