Based on the natural disaster risk evaluation mode, a quantitative danger degree evaluation model was developed to evaluate the danger degree of earth dam reservoir staged operation in the flood season. A formula for ...Based on the natural disaster risk evaluation mode, a quantitative danger degree evaluation model was developed to evaluate the danger degree of earth dam reservoir staged operation in the flood season. A formula for the overtopping risk rate of the earth dam reservoir staged operation was established, with consideration of the joint effect of flood and wind waves in the flood sub-seasons with the Monte Carlo method, and the integrated overtopping risk rate for the whole flood season was obtained via the total probability approach. A composite normalized function was used to transform the dam overtopping risk rate into the danger degree, on a scale of 0-1. Danger degree gradating criteria were divided by four significant characteristic values of the dam overtopping rate, and corresponding guidelines for danger evaluation are explained in detail in this paper. Examples indicated that the dam overtopping danger degree of the Chengbihe Reservoir in China was 0.33-0.57, within the range of moderate danger level, and the flood-limiting water level （FLWL） can be adjusted to 185.00 m for the early and main flood seasons, and 185.00-187.50 m for the late flood season. The proposed quantitative model offers a theoretical basis for determination of the value of the danger degree of an earth dam reservoir under normal operation as well as the optimal scheduling scheme for the reservoir in each stage of the flood season.展开更多
Floodwater utilization is an important content in flood management. Controlling the limit water level of reservoir by stage is one of important contents in the management of multi-purpose reservoir’s floodwater utili...Floodwater utilization is an important content in flood management. Controlling the limit water level of reservoir by stage is one of important contents in the management of multi-purpose reservoir’s floodwater utilization for the sake of more benefits, and reasonable division of stage in flood season is precondition of controlling the limit water level by stage. On the background of Three Gorges Reservoir floodwater utilization management and on the foundation of self-similarity of hydrological series, determining the number of flood season staged in base of conventional statistical method, choosing the Db4 wavelet and Mallat algorithm, the computation mode of wavelet fractal dimension estimation method is proposed and each stage’s fractal dimension is computed, then the final flood season staged is obtained. The results demonstrate the stages of Three Gorges Reservoir determined by using wavelet fractal dimension method are consistent with that from conventional method, but the fractal dimension results by former method are easier, more stable and objective which ensures the feasibility of the wavelet fractal dimension method applying in flood season staged. The obtained results are the base of deep coping with floodwater utilization management, also are the decision-making gist for the flood forecast, flood control and water allocation reasonably of Three Gorges Reservoir.展开更多
基金supported by the National Natural Science Foundation of China(Grants No.51569003 and 51579059)the Natural Science Foundation of Guangxi Province(Grant No.2017GXNSFAA198361)the Innovation Project of Guangxi Graduate Education(Grant No.YCSW2017052)
文摘Based on the natural disaster risk evaluation mode, a quantitative danger degree evaluation model was developed to evaluate the danger degree of earth dam reservoir staged operation in the flood season. A formula for the overtopping risk rate of the earth dam reservoir staged operation was established, with consideration of the joint effect of flood and wind waves in the flood sub-seasons with the Monte Carlo method, and the integrated overtopping risk rate for the whole flood season was obtained via the total probability approach. A composite normalized function was used to transform the dam overtopping risk rate into the danger degree, on a scale of 0-1. Danger degree gradating criteria were divided by four significant characteristic values of the dam overtopping rate, and corresponding guidelines for danger evaluation are explained in detail in this paper. Examples indicated that the dam overtopping danger degree of the Chengbihe Reservoir in China was 0.33-0.57, within the range of moderate danger level, and the flood-limiting water level （FLWL） can be adjusted to 185.00 m for the early and main flood seasons, and 185.00-187.50 m for the late flood season. The proposed quantitative model offers a theoretical basis for determination of the value of the danger degree of an earth dam reservoir under normal operation as well as the optimal scheduling scheme for the reservoir in each stage of the flood season.
基金Project supported bythe National Nature Science Foundation of China(No.6057407)
文摘Floodwater utilization is an important content in flood management. Controlling the limit water level of reservoir by stage is one of important contents in the management of multi-purpose reservoir’s floodwater utilization for the sake of more benefits, and reasonable division of stage in flood season is precondition of controlling the limit water level by stage. On the background of Three Gorges Reservoir floodwater utilization management and on the foundation of self-similarity of hydrological series, determining the number of flood season staged in base of conventional statistical method, choosing the Db4 wavelet and Mallat algorithm, the computation mode of wavelet fractal dimension estimation method is proposed and each stage’s fractal dimension is computed, then the final flood season staged is obtained. The results demonstrate the stages of Three Gorges Reservoir determined by using wavelet fractal dimension method are consistent with that from conventional method, but the fractal dimension results by former method are easier, more stable and objective which ensures the feasibility of the wavelet fractal dimension method applying in flood season staged. The obtained results are the base of deep coping with floodwater utilization management, also are the decision-making gist for the flood forecast, flood control and water allocation reasonably of Three Gorges Reservoir.
