浅水海湾排污扩散器初始稀释度的计算

流速和水深是影响浅水型海湾扩散器初始稀释能力的主要环境因素，其长时间序列的实测资料在现实中通常很难得到，而平面二维水动力模型的引入可为初始稀释度的计算提供必要和准确的水动力要素。通过建立二维水动力模型模拟受纳海域的流场，利用实测水文资料进行模型的率定和验证，模拟设计水文条件下附近水域的流场，然后提取排污口处的水深、流速和流向的时间序列，再利用近区模型计算任一时刻的初始稀释度，最后进行累积频率分析得到设计保证率下的初始稀释度。将该方法应用于杭州湾某排污扩散器初始稀释能力的评估，研究表明，利用远区模型为扩散器近区模拟提供环境水文要素，弥补了实际工程计算中缺乏实测水文资料的不足，并大大提高了近区模拟的计算精度。

Numerical computation of initial dilution ability for diffuser in shallow bay

Velocity and water deep are the main factors that determine the initial dilution ability of diffuser in shallow bay. The long period measured data is often impossible to get, and the 2-D hydrodynamic model can provide necessary and accurate data for the initial dilution ability computation. 2-D model including the wastewater disposal area is established and then are calibrated and verified using the measured hydrodynamic data of surrounding stations. Then flow field under designed hydrological condition is simulated, then the water deep, flow velocity and direction of disposal point are abstracted from the simulation results to compute the initial dilution ability. Then the designed dilution ability can be got by accumulation frequency analysis. This method is used in a dilution ability evaluation of a diffuser in Hangzhou Bay. The results showed that hydrodynamic simulation can provide hydrological data for near field simulation and can improve its accuracy.