危险品运输泄漏引发的河流污染事故模拟研究

Simulation of river pollution accidents caused by transportation leakage

针对农药运输过程中发生翻车泄漏事故造成的河流污染,结合SMS软件中的二维有限元水动力模块RMA2及美国环境保护署推出的WASP软件进行模拟研究。利用RMA2模拟水在河流系统中的物理运动,通过一定的转换规则将RMA2输出的结果转变为WASP所需要的形式,运行WASP得到污染物浓度在空间和时间上的变化规律并加以分析。模拟结果表明:在泄漏事故后不久,污染物还没有完全扩散到泄漏点对岸;在一段时间后,在横向扩散的作用下,污染物开始整个横断面上蔓延,断面横向浓度梯度不断减小,但还没有达到完全混合;断面浓度最大值开始从泄漏一侧向河流中心迁移。最后,针对研究案例提出与模拟结果相应的预警分析和应急措施。

In this paper, the authors have combined finite element hydrodynamic numerical module RMA2 of SMS and water quality simulation software WASP which launched by USEPA. The combination was applied to simulate a sudden river pollution incident caused by pesticide transportation accident happens in the rural area. First of all, the paper adopted the two-dimensional grid module GFGEN in SMS to create the geometry and finite element computational mesh files for use by means of hydrodynamic model RMA2. Then, RMA2 was used to describe the physical movement of water in the river system and the velocity components and water depth at each node were acquired as well. The RMA2 model was spatially defined by a set of nodes whereas the WASP model was spatially defined by a series of segments. By using some transformation methods, the RMA2 results have been transformed into input data form required by WASP. Finally, we have obtained the concentration of pollutants by running WASP and the concentration distribution regularities in space and time have been further analyzed. The simulation result shows that, shortly after the leak, the contaminants have not yet fully spread to the other side of leak point. After a period of time, the pollutions spread throughout the entire cross-section and lateral concentration gradient continually decreases, but not yet completely mixed. Under the effect of transverse dispersion, the location of maximum cross-section concentration changes from the side of spill to the river center. Lastly, we have proposed appropriate early stage warning and emergency measures in accordance with the corresponding simulation results.