突发性河流污染事故水质预警模型

An alarm model for unexpected river accidents

研究河流中污染物的输移扩散及其影响因素,引入死区预警模型及其解析解,模拟污染物在水体中的时空变化,进而预测污染物到达下游特定地点的浓度值及相应时间。实例模拟结果,尤其是对下游断面污染物最大浓度值及其出现时间的预测结果较好,表明建立的模型能够较准确地模拟河流中污染物的输移扩散规律。本研究可为环境风险管理及突发性环境污染应急预案的制定提供科学依据。

The paper is aimed to introduce an alarm model in hoping to assess the expected concentration of a pollution spot and its time of arrival at a partieular section of a river. First of all, a propagation model has been described on how the model has been developed. For the purpose, we have studied the influence of the dead zones（or ＂the transient storage zones＂ ） on the transition of dissolved matter in a river with an analytical solution method established. On the whole, the model is devised based on a one-dimensional approach for the migration or floating of dissolved matter, with different specific aspects described and discussed. The resultant effect of the transient storage in final analysis depends on the two aspects, i.e. the matter exchange rate coefficient and the volume or cross-sectional area of the transient storage zone. The said alarm model is in fact made of an adveetiondispersion equation for transition and migration of dissolved matter in the main channel with a first order matter exchange for describing the diffusive solutions transition to the transient storage zone. This system of equations is solved analytically for the case of an instantaneous injection of the pollution matter along the river with constant and uniform current. The solution helps to estimate the temporal and spatial evolution of the concentration at the lower reach injection point. The model has been tested in schematic scale, whose results prove its rationality in comparison with the monitoring data, especially for the peak concentration of the pollution and the time when the peak concentration occurs. And, finally, the simulating data and the monitoring data prove in close conformity with each other. Thus, it can be made to provide decision-makers with quantitative and qualitative reference information so as to improve the environmental hazard management and give timely emergency response to the accidents that take place unexpectedly with water pollution.