Study On Coastal Water Environmental Capacity By Complex System Theory

With the rapid economic development and the population booming in coastal zone, the coastal water quality was deteriorated. In order to control the coastal water pollution effectively, its characters and regulations must be mastered, based on which the coastal water environmental capacity could be calculated. In this dissertation, through the integrated using of complex system theory and computer software, the analyzation, prediction and assessment of the water quality in Tianjin coastal marine were studied totally based on the environmental monitoring data. Furthermore, a new calculation method for coastal water environmental capacity was proposed, which could supply the decision support for coastal pollution total amount control and environmental management.Firstly, based on fractional theory, the rescaled range analysis was used to compute the Hurst exponents H of the COD and inorganic nitrogen time series.The results showed that the Hurst exponents of the two water quality indexes were around 0.80, it proved that the coastal water quality pollution presents fractional characteristics. Then, based on multi-fractal theory, a typical multi-fractal method, which called the method of moments, was applied to compute the multi-fractal dimension spectrum function f(α) of the 20 monitoring points. From the results, we could found the curve ofα( q ? f(α) was a continuous curve. The results indicated that the spatial distributing mode of coastal water pollution was a continuous multi-fractal distribution.Secondly, according to the fractional collage theory, the fractal interpolation which based on affine transform was used to find the iterated function systems of historical water quality. The weighted summation method was used to find the iterated function system of predicting period according to the above iterated function systems, which was based on periodicity. Then the fractal predicting model was established according to the iterated function system of predicting period. Finally, the random iterated algorithm was used to find the attractor of each predicting periods which could provide the predicting data according to the time values. The predicting results showed that the average predicting error was 24.4%. Thirdly, a new assessment model for coastal water quality was proposed through the study on the nonlinear mapping theory and DPS software. Firstly, the high-dimension water quality data were mapped to two-dimension plane by nonlinear mapping method. Secondly, the water quality assessment model was established according to location of the mapping points. So the water quality assessment could be simplified and improved.At last, based on the results obtained in the chapter 2 and fractal surface interpolated algorithm, a new method for estimation of organic substance concentration in coastal marine was proposed. The MATLAB program of the fractal surface interpolation algorithm was made to estimate the concentration of the organic substance in coastal marine. Then, the COD concentration of organic substance in the whole area was gotten. Finally, the water environmental capacity under the worst condition was calculated according to the conservation of mass.