Characteristic Analysis and Loss Accounting for Water Pollution in Plain River Network Region - A Case Study of the Yangtze Delta

Because there are many water systems, severe human activities, increasingly serious water pollution problems and great economic loss in the plain river network region, the establishment of scientific and reasonable economic loss function is necessary to guide the protection and management of water resources. Taking the Yangtze Delta as an example, the characteristics of water pollution in the same period are that the flood season is stronger than the non-flood season. The analysis based on the physical mechanism shows that the process of economic loss of water pollution not only accords with S-type curve but also gives a reason for the S-type curve from the aspect of mechanism. The water pollution loss rate function which is constructed on the basis of hyperbolic tangent function divides the development stage into such three stages as non-enrichment, enrichment and saturation of pollutants, gives turning points of each stage as well as the solution and significance of parameters and enriches the physical process of models. The results of living samples show that the comprehensive water grades can be obtained easily and quickly through the river length failure rate. Their good correlation has certain promotion significance. The total water pollution economic loss is bigger. The average economic loss in the flood period from May to July is bigger than that in the flood period from August to September and non-flood period. The living samples prove that there exists pollutant diffusion phenomenon in the flood period.