大宁水库库尾位于交通节点附近，存在交通事故引发突发性水污染事故的风险。从风险防范与管理角度，利用MIKE21FM模型，以5 t硝基苯泄露为例，考虑风、水库调度因素，设定5个情景开展突发事故污染物扩散规律研究。结果表明：(1)不同情景污染物扩散速度和超标水域面积相差较大。无风、不调度情景下，库区水体接近静止，污染物扩散速度最慢；水库向大宁调压池输水20m3/s，西北风12.3 m/s情景下，污染物扩散速度最快。(2）与常规调度相比，风速和风向对污染物的扩散影响更大。同样风速情况下，西北风较东北风更利于污染物的扩散。(3）正常情况下（即风速不超过2.56 km/s，调水不超过20 m3/s），5 t硝基苯泄露应急响应时间在15 h以上，最不利情况下（风速为20年最大平均风速12.3 m/s且调水20 m3/s），应急响应时间为4～9 h。根据研究结果，一方面建议加强库尾交通疏导，加固桥梁护栏，降低交通事故发生概率；另一方面，建议在现有监测站点规划基础上，新增库尾自动监测站一处。

There is risk of accidental water pollution caused by traffic accidents near the tail of Da’ning reservoir, which is located near the traffic node. In this paper, the leakage of 5 tons of nitrobenzene was used as an example and five scenarios considering the effects of wind and reservoir regulation were developed to investigate the dispersion characteristics of pollutants based on MIKE21FM. The results showed that: (1) the differences of pollutant dispersion speed and overstandard water area were significant under different scenarios. The reservoir water was almost static and the pollutant dispersion speed was the slowest under the scenario without wind speed and reservoir regulation, while the pollutant speed was the highest under the scenario that the northwest wind speed was 12.3 m/s and the conveyance water rate from the reservoir to Da’ning surge pool was 20 m3/s; (2) compared with reservoir regulation, wind speed and direction had higher impacts on the pollutant dispersion. Northwest wind was better for pollutant dispersion than northeast wind when both wind speeds were equal; and (3) the emergency response time for leakage of 5 tons of nitrobenzene was more than 15 hours under normal conditions (wind speed was no more than 2.56 m/s and conveyance water rate was no more than 20 m3/s), while for the emergency response time was about 4 to 9 hours under the worst conditions (northwest wind was 12.3 m/s and conveyance water rate was 20 m3/s). The results suggested that the traffic management near the tail of the reservoir needs to be strengthened and the bridge parapets should be reinforced in order to reduce the traffic accident probability, and an automatic monitoring station near the trail of reservoir may be better constructed besides the other monitoring stations determined by the former planning.

北京市科委南水北调来水生态风险应对关键技术研究课题（Z121100000312097）