1998年の大洪水を想定した三峡ダムによる長江中流域の洪水抑止効果

抄録

To evaluate the protection effect of the Three Gorges Dam Project (TGP) on the flood in the middle region of the Changjiang River basin, we applied the integrated watershed hydrological model using gauged daily precipitation data of 1998 when the second largest flood occurred in the basin in the last century. From the results simulated by applying the discharge volume controlled by each upper limitation value from 40, 000 m³/s to 60, 000 m³/s, we could not find the clear effect on the reduction of the water level during flood period not only in the Dongting Lake but also in the Changjiang mainstream in the cases that the upper limitation discharge value were over 50, 000 m³/s. In the case that the upper limitation value was 40, 000m³/s, although the flood protection effect was clearly exerted in both the mainstream and the lake, the simulated storage volume of TGP remarkably exceeded the total flood control volume (221.5×10⁸ m³) at the peak of inflow to TGP. These results suggested that TGP flood control ability does not efficiently work for the decrease of flood damage in the middle region of the Changjiang basin in case of the occurrence of 1998 type flood phenomena.