Research Of Flood Control Level Of Fengjiashan Reservoir In Flood Season Based On Fuzzy Theory

Reservoir plays an important role in flood control and disaster mitigation. The flood control level of reservoir is an important index in reservoir flood control and operation. Flood control level not only affects the safety of the reservoir in flood season, but also the reservoir benefit of the reservoir in the non-flood season. Therefore it is necessary to research the flood control level of reservoir in flood season in the premise of the safety of reservoir. Through more than 30 years'operation Fengjiashan reservoir has created huge economic benefits and social benefits for Baoji City. However with the economic and social development of Baoji City, the conflict between flood control and reservoir benefit of Fengjiashan reservoir is becoming more and more intensified. In this case, the author used relative methods of fuzzy theory to research the flood control level of Fengjiashan reservoir in flood season. The content and the conclusions are as follows:(1)In this paper, the flood control level of Fengjiashan reservoir was analyzed using overtopping fuzzy risk model and fuzzy set analysis method.(2) The analysis of Fengjiashan reservoir using overtopping fuzzy risk model showed overtopping risk of Fengjiashan reservoir increased as its flood control level increased.(3) The results of overtopping fuzzy risk model of Fengjiashan reservoir showed that when the flood control level increased from 707m to 708.80m the maximum fuzzy risk mean was 6.107×10-5, which is lower than the criterion fuzzy risk of 7.12×10-5; when the flood control level was708.90m the fuzzy risk mean was higher than the criterion fuzzy risk.Therefore the overtopping risk of Fengjiashan reservoir is acceptable when the flood control level increased from 707m to 708.80m and the water storage capacity of Fengjiashan Reservoir increased by 26 million m3.(4) Compared with the current division of flood season of Fengjiashan Reservoir, regarding the fuzzy division of flood season using fuzzy set analysis method, the date of the end July 1st of the pre-flood season was postponed to July 14th, latter flood season was advanced from October 1st to September 5th, and the flood control level is higher than the current flood control level; the date of start and end of the main flood season changed, and the flood control level is the same as the current flood control level. Compared to the current operation program, the abandoned water in flood season, especially in the main flood season was decreased, and the utilization efficiency of water resources was improved.(5)Compared to the current running programs of Fengjiashan Reservoir, the calculated flood control level curve had no sudden change as the current flood control level did.The flood control level of Fengjiashan Reservoir obtained by the fuzzy set analysis was feasible in the actual operation, although it was changing in operational process.Particularly with the application of automatic management system Fengjiashan reservoir, the efficiency of water utilization is highly improved. Once the calculated flood control level curve using fuzzy set analysis method was adopted, the volume of abandoned water decreased, and thereby the water hennessy of Fengjiashan reservoir increased.