Study On The Effect Of Urbanization Process On Water Quality And Regularity Of Accidental Water Pollution

The Stage of rapid urbanization has come to Chinese cities, bringing seriousenvironmental problems,such as urban water quality deterioration, and accidentalwater pollution. These problems were valued by the government and society. And ithas been a realistic issue to solve or avoid the problems. To elaborate the waterpollution problems in urbanization process and to find effective countermeasure, therelationship between water quality and urbanziation, regulatity and self-organizedcriticality of accidental water pollution would be studied in this research.The effect of urbanization process on the urban water quality was studied firstly.A multi-index comprehensive evaluation system for characterizing the impact ofurbanization on the water quality was developed by an improved Analytic HierarchyProcess. The indices of the system included two parts: positive and negative,according to their effects on the water quality. In the system, the values of indicesfor the effects of economic growth and daily environmental protection investmenton water quality were obtained by two nonlinear functions which can reflect thepractical process. By developing an evaluation model of the system, the waterquality of a city could be estimated according to its urbanization characteristics. Theparameters in the model were estimated by the2001-2010data of Zunyi city’s urbandevelopment and water quality. The model was verified with the data of Harbin,with good accuracy of the model and the universality of the index system. Throughthe analysis of the factors in the model, the coordinated development route betweeneconomy and environment investment was proposed. And the growth of populationdid not often play a dominant role in the urban water quality deterioration.Another effect of urbanization on urban water system was the accidental waterpollution, so the growth pattern of accidental water pollution in the process ofurbanization was studied. Taking Guangdong Province as the research object, thenumber of accidental water pollution presented a Logistic growth pattern, with thedevelopment of driven factors for accidental water pollution in urbanization process.Then, the meanings of parameters in the Logistic equation were analyzed. With thechange of the environmental management factors, the accidental water pollution’sgrowth pattern would be changed. So the strength, efficiency and mechanism ofenvironmental management were very important to the accidental water pollutioncontrolling. And assessment of environmental management level should be takeninto consideration in the process of pollution risk assessment. Finally, traditionalrisk assessment process and risk management level assessment were united, and arelatively comprehensive risk assessment process was established. Finally, the self-organized criticality (SOC) of accidental water pollution inChina was discussed. With frequency-size analysis, power spectral analysis andrescaled range analysis of water cut-off time and the number of casualties in waterpollution events of China, spatial fractal structure,1/f noise and the long-rangecorrelation are found, suggesting the existence of self-organized criticality in theevents. Because of the characteristics of the SOC, without enough attention, minorwater pollution events could trigger the occurrence of high water pollution events bySOC behavior in social system. Making an analogy between water pollution eventsand the classic sand pile model in SOC, some similarity are found, but waterpollution events are associated with various social factors. So the sand pile modelcannot be simply applied to water pollution events. With rescaled range analysis, inthe time scale of year and month, the water pollution events have long-rangecorrelation and continuity. Taking the expanding scale of water pollution intoconsideration, it means that the dangerous degree of water pollution has the trend offurther improvement.