NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 1...NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.展开更多
On September 10, 2015, unprecedented flood was occurred in Kinugawa River basin located on eastern Japan. It inundated 40 km2 of flood plain in Joso city, Ibaraki Prefecture, and more than 4000 people there called for...On September 10, 2015, unprecedented flood was occurred in Kinugawa River basin located on eastern Japan. It inundated 40 km2 of flood plain in Joso city, Ibaraki Prefecture, and more than 4000 people there called for help despite supposedly having sufficient time to evacuate. Some said that small initial flood before main severe flood arrived made them make a mistake in deciding whether to evacuate or stay there, despite having to actually evacuate in reality. This study focused on flood behaviour in this area, in particular, the effect of a small drainage channel lying on the flood plain which caused fast flood diffusion in case of occurring huge overflowing. Field investigations starting on time of the disaster with high-resolution positioning system were conducted to obtain spatial maps of flood depth and height. For appropriate modelling of the effect of small channel, we applied simulation model coupling 1-dimensional (1D) and 2-dimensional (2D) hydraulic scheme on the field and compared results from the 1D/2D coupled model and model without 1D scheme. The models provided information that the flood could reach 4 hours earlier to the city central of Joso city comparing in case of model without 1D scheme. The water depth rose irregularly and it was more confusing and difficult for the victims to make appropriate evacuation act.展开更多
The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional （l-D） mathematical mode...The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional （l-D） mathematical model for flood routing in the river network Of the Jingjiang River and Dongting Lake using the explicit finite volume method. Based on observed data during the flood periods in 1996 and 1998, the model was calibrated and validated, and the results show that the model is effective and has high accuracy. In addition, the one-dimensional mathematical model for the river network and the horizontal two-dimensional （2-D） mathematical model for the Jingjiang flood diversion area were coupled to simulate the flood process in the Jingjiang River, Dongting Lake, and the Jingjiang flood diversion area. The calculated results of the coupled model are consistent with the practical processes. Meanwhile, the results show that the flood diversion has significant effects on the decrease of the peak water level at the Shashi and Chenjiawan hydrological stations near the flood diversion gates, and the effect is more obvious in the downstream than in the upstream.展开更多
In recent years, the Cavally River has been subject to multiple activities, <span style="font-family:;" "="">including the construction of diversion channels and a bridge that makes it v...In recent years, the Cavally River has been subject to multiple activities, <span style="font-family:;" "="">including the construction of diversion channels and a bridge that makes it vulnerable to flooding. In order to assess the impact of these hydraulic structures on the <span>river hydrodynamic functioning, a 1D-2D model was realized. The</span> implementation of the 1D-2D model consisted </span><span style="font-family:;" "="">of </span><span style="font-family:;" "="">first </span><span style="font-family:;" "="">running</span><span style="font-family:;" "=""> </span><span style="font-family:;" "="">the 1D model, then the 2D model, and finally in coupling them. The 1D-2D model was designed with <span>the 1988 flood hydrograph, a Manning’s coefficient of 0.052 m<sup>1/3</sup>/s for the </span>minor bed and 0.06 m<sup>1/3</sup>/s for the major bed. The results of the hydraulic model show that the velocities are almost identical to those of the Cavally in natural operation. The values of the velocities are included between 0.4 m/s and 1.3 m/s at the level of the minor bed of the river and between 0.06 m/s and 0.71 m/s at the level of the floodplains. The average water level for flood propagation is 262.37 ± 0.44 m before construction of the structures and 262.23 ± <span>0.85 m after construction of the structures. The 0.41 m reduction in water</span> level due to the diversion canal and bridge is negligible compared to the total fluctuations of the Cavally River, which vary from 6 to 7 m over the year.</span>展开更多
基金National Natural Science Foundation of China(41275080)China Meteorological Administration Special Public Welfare Research Fund(GYHY201306022)Open Research Fund Program of Plateau Atmosphere and Environment Key Laboratory of Sichuan Province(PAEKL-2010-C3)
文摘NCEP/NCAR reanalysis data and a 30-year precipitation dataset of observed daily rainfall from 109 gauge stations are utilized in this paper.Using the REOF we analyzed the spatial distribution of precipitation in the 109 stations in the Yangtze River Basin in Meiyu periods from 1978 to 2007.The result showed that the spatial distribution of precipitation in the Yangtze River Basin can be divided into the south and north part.As a result,relationships between an atmospheric heating source(hereafter called <Q_1>) over the Asian region and the precipitation on the south and north side of Yangtze River in Meiyu periods were separately studied in this paper.The results are shown as follows.The flood/drought to the north of Yangtze River(NYR) was mainly related to the <Q_1> over the East Asia summer monsoon region:when the <Q_1> over the Philippines through Western Pacific and the south China was weakened(strengthened),it would probably result in the flood(drought) in NYR;and the precipitation on the south side of Yangtze River(SYR)was related to the <Q_1> over the east Asia and Indian summer monsoon region:when the <Q_1> over the areas from south China to the northern East China Sea and Yellow Sea and south-eastern Japan was strengthened(weakened),and the <Q_1> over the areas from the Bay of Bengal to south-eastern Tibetan Plateau was weakened(strengthened),it will lead to flood(drought) in SYR.
文摘On September 10, 2015, unprecedented flood was occurred in Kinugawa River basin located on eastern Japan. It inundated 40 km2 of flood plain in Joso city, Ibaraki Prefecture, and more than 4000 people there called for help despite supposedly having sufficient time to evacuate. Some said that small initial flood before main severe flood arrived made them make a mistake in deciding whether to evacuate or stay there, despite having to actually evacuate in reality. This study focused on flood behaviour in this area, in particular, the effect of a small drainage channel lying on the flood plain which caused fast flood diffusion in case of occurring huge overflowing. Field investigations starting on time of the disaster with high-resolution positioning system were conducted to obtain spatial maps of flood depth and height. For appropriate modelling of the effect of small channel, we applied simulation model coupling 1-dimensional (1D) and 2-dimensional (2D) hydraulic scheme on the field and compared results from the 1D/2D coupled model and model without 1D scheme. The models provided information that the flood could reach 4 hours earlier to the city central of Joso city comparing in case of model without 1D scheme. The water depth rose irregularly and it was more confusing and difficult for the victims to make appropriate evacuation act.
基金supported by the National Key Technologies Research and Development Program (Grant No. 2006BAB05B02)
文摘The main stream of the Yangtze River, Dongting Lake, and the river network in the Jingjiang reach of the Yangtze River constitute a complex water system. This paper develops a one-dimensional （l-D） mathematical model for flood routing in the river network Of the Jingjiang River and Dongting Lake using the explicit finite volume method. Based on observed data during the flood periods in 1996 and 1998, the model was calibrated and validated, and the results show that the model is effective and has high accuracy. In addition, the one-dimensional mathematical model for the river network and the horizontal two-dimensional （2-D） mathematical model for the Jingjiang flood diversion area were coupled to simulate the flood process in the Jingjiang River, Dongting Lake, and the Jingjiang flood diversion area. The calculated results of the coupled model are consistent with the practical processes. Meanwhile, the results show that the flood diversion has significant effects on the decrease of the peak water level at the Shashi and Chenjiawan hydrological stations near the flood diversion gates, and the effect is more obvious in the downstream than in the upstream.
文摘In recent years, the Cavally River has been subject to multiple activities, <span style="font-family:;" "="">including the construction of diversion channels and a bridge that makes it vulnerable to flooding. In order to assess the impact of these hydraulic structures on the <span>river hydrodynamic functioning, a 1D-2D model was realized. The</span> implementation of the 1D-2D model consisted </span><span style="font-family:;" "="">of </span><span style="font-family:;" "="">first </span><span style="font-family:;" "="">running</span><span style="font-family:;" "=""> </span><span style="font-family:;" "="">the 1D model, then the 2D model, and finally in coupling them. The 1D-2D model was designed with <span>the 1988 flood hydrograph, a Manning’s coefficient of 0.052 m<sup>1/3</sup>/s for the </span>minor bed and 0.06 m<sup>1/3</sup>/s for the major bed. The results of the hydraulic model show that the velocities are almost identical to those of the Cavally in natural operation. The values of the velocities are included between 0.4 m/s and 1.3 m/s at the level of the minor bed of the river and between 0.06 m/s and 0.71 m/s at the level of the floodplains. The average water level for flood propagation is 262.37 ± 0.44 m before construction of the structures and 262.23 ± <span>0.85 m after construction of the structures. The 0.41 m reduction in water</span> level due to the diversion canal and bridge is negligible compared to the total fluctuations of the Cavally River, which vary from 6 to 7 m over the year.</span>
