Study On Water Environment Assessment In Fuzhou River Basin Based On Grey Water Footprint

Since the implementation of the strictest water resources management system in China,"three red lines"and"four systems"have been strictly implemented in various regions,which has effectively improved China’s water environment.The 14th five-year plan further proposes to establish and improve the environmental governance system,promote accurate,scientific,legal and systematic pollution control,and continuously improve the quality of water environment.Scientific and reasonable evaluation of convective water environment is the premise of accurate prevention and control of water pollution.Based on the water footprint theory and SWAT model,this paper constructs and optimizes the accounting method of grey water footprint,analyzes the characteristics of grey water footprint and nitrogen and phosphorus pollution in Fuzhou River Basin,evaluates the water environmental pollution in the basin,and puts forward the countermeasures and management suggestions for water pollution control in Fuzhou River basin.The main contents of this paper are as follows:(1)Establish and optimize the grey water footprint calculation method of the basin.This paper has collected various pollution data in the Fuzhou River Basin through multiple field surveys and collected data.And based on water footprint theory and statistical data,this paper constructs a grey water footprint calculation method for the basin,solves the problem of one-sided and repetitive calculation of pollution sources in the grey water footprint calculation process of the basin,and clarifies the principles and norms for the selection of various parameters.In addition,this paper uses the SWAT model to further optimize the grey water footprint calculation method of the Fuzhou River Basin,and uses SWAT to simulate the hydrology and nutrient cycle of the river basin to obtain the pollution discharge value generated during the industrial and agricultural production process of the river basin,which is used to calculate the Grey water footprint of Fuzhou River Basin.To a certain extent,it solves the problem of grey water footprint accounting in the basin under the circumstances of fuzzy and missing pollution data,and at the same time gives grey water footprint accounting a hydrological cycle mechanism.(2)Evaluate the water environment and the characteristics of nitrogen and phosphorus pollution in the Fuzhou River Basin.We went to the Fuzhou River three times from August to September 2018 to conduct water sample collection and cross-sectional water quality measurement,so as to understand the pollution of the river’s water body.On this basis,this paper uses pollution statistics to analyze the value and spatial characteristics of the gray water footprint in the Fuzhou River Basin in 2016 from four pollution sources:industry,residents’life,livestock and poultry breeding,and planting.At the same time,the SWAT model output data is used to compare and analyze the gray water footprint value and temporal and spatial characteristics of the Fuzhou River Basin from 2013 to 2016.The results show that the grey water footprints of the two types of data calculated in 2016 are similar to 4.115 billion m~3 and4.374 billion m~3.Finally,the quantitative and spatial characteristics of nitrogen in the Fuzhou River basin were analyzed using the simulation results of the SWAT model,together with the changes of nitrogen and phosphorus loss in the Fuzhou River basin under different rainfall and fertilization scenarios.(3)Put forward countermeasures and management suggestions for water pollution prevention and control in the Fuzhou River Basin.Based on the results of the Fuzhou River water environment assessment,this paper uses the SWAT model to construct a back-calculation method for the upstream pollution load of the river basin,which in order to infer the pollution load thresholds of the upstream catchment areas on the basis of ensuring that the outlet of the Fuzhou River Basin is Grade III surface water.Based on the above research results,this article finally puts forward the prevention and control measures and management suggestions for the pollution problems of the Fuzhou River Basin industry,residents’lives,livestock and poultry breeding industry and planting industry,and provide reference for the pollution control of Fuzhou River in the later period.