中文摘要：

无论采用解析计算还是数学模拟对河流污染混合区开展分析，其计算参数的准确性比选择不同数学模型对预测结果的影响更大，应予以重视。基于宽阔河流污染混合区几何特征尺度的理论公式，分析并提出了采用多年平均枯水期流量确定环境设计流量的方法和考虑排污风-险修正系数的排污强度确定方法，给出了河流污染混合区各计算参数正、负误差分别引起的最大长度、最大宽度和面积误差的敏感性排序。结果表明，水深、流速和横向扩散系数的正误差会减小污染混合区范围，而排污强度的正误差则会增大污染范围，而且，污染混合区几何特征尺度的误差变化幅度远超过其计算参数的误差变化幅度，揭示了计算误差的放大效应。

英文摘要：

The accuracy of the parameters of the calculation condition influences the predicted results of pollutant mixing zone more than the selection of different mathematical models regardless of whether the analytic calculation or the mathematical simula- tion is used. Based on the theoretical formula of the geometric characteristic scale of the pollutant mixing zone in broad rivers, the methods to determine the environmental design flow with the average flow in dry seasons and the emission intensity of the pollutant discharge were analyzed and proposed by considering its risk correction factor, and then the ranks of the error sensitivity of the maximum length, maximum width and area caused by the positive and negative error of each calculation parameter in pollutant mixing zone are given. The results show that the positive error of water depth, flow velocity and transverse diffusion coefficient would decrease the calculated scope of the pollutant mixing zone while the positive error of the emission intensity would increase the calculated scope of the pollutant mixing zone, so the error variation range of the pollutant mixing zone is far larger than that of the calculation parameters, which reveals the amplification effect against the calculation error.