Characteristics of precipitation and discharge using a pseudo global warming experiment result of the typhoon No.12, 2011 in the River Shingu,JAPAN

Abstract:

Mitigation countermeasures as the strategy to reduce risk of climate change have been promoted in Japan. The significant issue of the disaster mitigation was the increasing risk of the disaster in the future. It is necessary to predict the change of the basin average precipitation and river discharge in the future in order to execute the disaster mitigation.In this study, first, we summarized the data of the real precipitation and flooding brought by the typhoon No,12, Sep. 2011(Tales), which had set the Japanese highest discharge ever. The average basin rainfall duration 2days in the upstream area of the Aiga at the flood control reference point shown in Fig. 1 is 1,220 mm, and the peak discharge at the Aiga point is estimated to be approximately 24,000 m3/s, which exceeds the planned high water of 19,000 m3/s. Table 1 shows the rainfall in the upstream area of the Aiga region in the simulated warming experiment case. From these cases, rainfall characteristics are shown for Case110, which shows the maximum hourly precipitaion of basin average precipitaiton, and for Case120, whose runoff is equivalent to the peak discharge of 32,000 m3/s due to the assumed maximum-scale rainfall of the relevant water system announced in 2016. Second, we try to reproduce of the track and precipitation of the Tales. We had conducted the pseudo global warning experiment for the Tales in consideration of the conditions under which the seawater and atmosphere temperature in the Pacific Ocean was raised by 4℃. The prediction data which were provided by the Program for risk information on climate change were employed in this study. We compared the changes of the precipitation of the basin and sub-basin with the real ones. Furthermore, we evaluated the river discharge calculated by employing with the distribution cell runoff model. Furthermore, using these rainfalls as input conditions, we evaluated the changes in runoff characteristics due to typhoon tracks using a distributed runoff model. In the case of pseudo-warming experiment, the maximum is about 47,000 m3/s. This is about twice the actual value.The results of this study were shown below.1) As a result of comparison the predicted precipitation with the real one, precipitation during 2days were less than one of the real. On the other hands, precipitation during 24hr were more than one of the real. In Figure.2 This is because the typhoon's power becomes stronger and the northward velocity becomes faster. On the other hand, it was found that the total rainfall was smaller than the actual one, resulting in a large amount of rainfall in a short time.