基于Matlab软件的突发事故水质解析模型与应用

为快速分析突发性水污染事故可能造成的水环境影响,建立了基于Matlab软件的突发事故水质解析模型。以浙江省某河流为例,分析了上游突发水污染事故形成的污染团在河流中的迁移扩散规律、影响范围、事故下游各断面水质变化过程以及取水口等敏感点的超标时间及超标程度。同时详细分析了近岸和远岸边界对污染物反射所造成的浓度叠加影响、合理的边界反射次数,以及水流流速、扩散系数、降解系数等主要水文水质参数对污染团扩散的影响。

A water quality analytic model and its application to unexpected accidents based on the Matlab software

The given paper is aimed at introducing a water quality analytic model for analyzing and determining the unexpected accidents based on the Matlab software,while considering necessary random factors,such as the migrating and transient loads,diffusion and boundary reflections involving the proposed model.Taking a river in Zhejiang as a case study sample,we have analyzed the regularity of its water change and pollution mass features,as well as the dumping situation at its upper-reach streams.In addition,we have also worked out its substandard pollutant range,on-spot concentration distribution,the process of its water-pollutant concentration change,for example,its water intakes.Besides,we have discussed the influential factors of the river boundaries and its water receiving seasonal change features,too.Mention has also been made of the water current velocity,diffusion coefficient and degradation coefficient of the pollution mass spreading.As the result of our investigation and statistics,we have gained the following basic parameters of the above listed items,such as: the sum-total of leakage mass of the river pollutants is about 15 tons;the distance of a given leakage point to the nearest boundary is within a 100 meters: the degradation coefficient—0.10 d-1,the velocity of x direction—0.5 m/s,river width—500 m;water depth—at about 3 m;and the background concentration—4 mg/L.In addition,2 hours later,when an unexpected accident took place,the highest concentration of pollutant mass would be rising as high as 10.82 mg/L,with a substandard area getting to 0.24 km2.Furthermore,we have worked out the concentration process of the water intake at a 10 km downstream leakage point.In conclusion, it can be said that the accidental harm to the water intake can last about 2 hours,with the highest concentration being 7.92 mg/L in the whole process.Moreover,if there were more than twice reflection took place from the two boundaries, the concentration effects of the upper places would become insignificant.Therefore,it is not difficult to find the precision of the concentration computation tends to be acceptable when the nearest boundary reflection is beyond 12 times,though the other boundary reflection can be neglected.The results of our analysis can thus be used to provide useful reference for the methods in building warning models for any urgent or unexpected water pollution accidents.