Technical Studies

Issues assouiated with climate change have been discussed in different countries around the world. The floods due to climate change can probably cause serious damage on lives and properties. United Nations (UN) Announces a statement that under the unpredictable extreme climate, huge damage loss will become a “new normal”. That is why we must comprehend the impact of extreme hydrologic events to existing flood early warning, and this will be helpful. Establishment of warning stage has its basic assumptions and limitations of physiography and hydrology. 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. Research results of this project in Chapter 3 include completion of warning stage revision of 25 central govermental rivers and 15 drainage systems. We take representative typhoons and heavy rain events (top ten hydrologic events in basin in recent ten years) into consideration to provide reference and comparison for warning stage in 2013. In Chapter 4, we assess the influence of rainfall characteristics under near future (from 2015 to 2039) and far future (from 2075 to 2099) climate change to warning stage, the rising rate trend of warning stage under climate change, and the probability of overflow and beyond the 1st warning stage. In Chapter 5, we discuss the influence of bed changes in central govermental rivers on warning stage. According to cross-section data over the years and the rising rate trend of floods, we can assess the applicability of existing warning stage, and then propose suggestion to adjust control elevation of stages stations if necessary. According to the analysis results from Chapter 3 to Chapter 5 shown as summary table 1, those are recommended warning stage values of past years and for 2013. Finally, we develop automation display system for warning rainfall which is used in Fifth River Management Office, WRA.