用Markov模型预测长江水质

由于长江水质的污染程度日益严重，为了说明治理长江对长江水质进行了简单的评价,保护长江迫在眉睫，首先，根据长江流域的17个观测站近两年多的水质检测数据统计，说明了近两年多来长江的防污治理工作有一定的效果。然后，根据1995~2004年长江流域水质的数据报告，考虑各类水之间的相互转化，构造了马尔柯夫(Markov)转移矩阵，建立了马尔柯夫预测模型，通过已有的观测数据验证了该模型的正确性及有效性。运用该马尔柯夫模型预测未来10年水质的变化趋势，即Ⅰ、Ⅱ、Ⅲ、Ⅳ类水逐年减少,而Ⅴ、劣Ⅴ类水逐年增加。到2014年，长江的第Ⅰ类水只有0.4 059%，劣Ⅴ类水达到26.2 714%，不可饮用水（即第Ⅳ,Ⅴ,劣Ⅴ类水）将达到47.468%，为此应采取更加有效的治理措施，控制长江水质的恶化。最后，通过计算，得到了每年需要处理污水的最小百分比，才能杜绝劣Ⅴ类水，将第Ⅳ、Ⅴ类水控制在20%内，从而才能保证我们有足够的饮用水

FORECASTING WATER QUALITY OF THE YANGTZE RIVER USING MARKOV MODEL

The water quality in the Yangtze River has become worse from time to time,and thus to control the water quality and to protect the river have been a major issue for sustainable development in the region.In this paper,a model for the prediction of water quality in the river has been established,and this will provide reference values for any control measures to be taken for the protection of the water quality.First,by using the water quality data in 17 observation stations obtained within recent two years in the Yangtze River,a simple evaluation of the water quality in the river was conducted,and it is shown that the recent measures taken for the control of the water quality in the Yangtze River had some positive effect for improving the water quality.Second,the water quality data obtained from 1995 to 2004 in the Yangtze River were used,and the Markov transferred matrix is structured,with the Markov model established.The accuracy and the validity of the model were confirmed by the observed data.The water quality in the Yangtze River in the next ten years is then forecasted by the Markov model.That is,the standards I,II,III,IV water will reduce year by year,and the V,the poor standard V water will increase gradualy.To 2014,the kind I water in the Yangtze River only has 0.405 9 percent,the poor kind V water will be 26.2714 percent,the undrinkable water(namely IV,V and the poor V water) will reach 47.468 percent.Therefore,we must find a much more effective way to control deterioration of the water quality in the Yangtze River.Finally,through the computation,the smallest percentages of sewage water to be processed each year were obtained.The poor kind V water might be prohibited,and the kinds IV and the poor V water might be controlled in 20%,thus guaranteeing that we have enough drinking-water source.