以北京密云水库上游曹家路小流域为实例，建立了水环境模型，采用实测数据进行参数率定和模型验证；通过敏感性分析，选择上层出流系数，分析了该参数不确定性对流量（Q）和总无机氮（TIN）模拟结果的影响，并建立了联合隶属度函数。最后采用α-剪切方法，研究了不同剪切水平下Q和删模拟结果的综合安全度和综合不确定性区间的变化，结果表明：当a在O．45附近时，时间序列模拟结果和峰值模拟结果的综合安全度与可靠度达到最优，并给出了最优情况下Q和删的模拟结果及安全区间。%Uncertainty in model results is crucial to management and decision making. The study focused on parameter-induced uncertainty in a water quality model for the Caojialu catchment of the Miyun reser- voir in Beijing. The modeled variables were discharge （Q） and total inorganic nitrogen （TIN）. The model was calibrated and validated by field observations, Through sensitivity analyses, the upper zone drainage co- efficient （UZK） was selected for uncertainty analyses. By using fuzzy logic theory, the membership degree of UZK was defined. The a-Cut method combined with Monte Carlo simulation was used to investigate the relationship between uncertainty interval and safety degree of the model results under different a-Cut level. It was found that when a increased from 0.15 to 0.65, the effect on safety degree was slight. When ct Cut at 0.45, the safety degree and uncertainty interval of the model results reached to a ioint optimal.
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