Research On Water Pollution Load Distribution Model Based On Basin Control Unit

The Minjiang River is an important tributary of the Yangtze River in China.The Meishan section of the Minjiang River Basin,as a river that inherits Chengdu and runs through the main areas of Meishan City,is responsible for drinking water for residents of Pengshan,Dongpo,Qingshen in Meishan City and some counties and districts of Renshou,Danling Source and pollution burden.The quality of its water has a vital impact on the residents’ drinking water and production water.In recent years,Sichuan Province has responded to the requirements of the State Council on the prevention and control of watershed pollution by printing and distributing the provincial level watershed prevention and control work plan,which has put forward specific tasks for the management and control of the water environment in the river basin.Based on the secondary pollution data,this study divides the control unit of the Minjiang River Basin,and then uses the control unit as the basis to calculate the water pollution load of the Meishan section of the Minjiang River Basin from the aspects of industrial pollution sources,agricultural pollution sources,domestic pollution sources,and urban runoff;Total amount control,using the entropy weight method and the Critic method combined weighting multi-criteria decision-making and multi-objective optimization model to distribute the pollution load of the towns in different control units,which is the pollution prevention and control target between the control unit basin management bureau and the township government Provide reference and provide suggestions for the formulation of policies and laws for governments at all levels.The main research content and conclusions of this article are as follows:1.Based on the control unit,calculate the water pollution load of the Meishan section of the Minjiang River Basin from the aspects of industrial pollution source,agricultural pollution source,domestic pollution source,urban runoff,etc.,and determine the total pollution discharge of each control unit.The results show that the largest contribution to pollution emissions in the basin is the control unit of the Jiangxi area of Dongpo District and the control unit of the Jiangdong area of Dongpo District.The emissions of COD,ammonia nitrogen,and total phosphorus accounted for 59.18%,55.84%,and 58.97% of the total respectively.Livestock and poultry breeding and planting are the main sources of pollution in the Meishan section of the Minjiang River Basin.2.Construct a pollution load distribution index system based on the total control perspective,adopt the combination of entropy weight method and Critic method to assign weights,and establish a multi-criteria distribution model of water pollution load based on the control unit watershed management bureau and the townships in the unit.The results show that some towns and villages in the control units of the Meishan section of the Minjiang River Basin need to be controlled.The control units with serious pollution discharge and uneven distribution ratio of pollution discharge are mainly the control sub-units of Jiangdong and Jiangxi in Dongpo District and the control sub-units of Heilongtan Reservoir.The government needs to carry out key pollution prevention and control;in addition,some towns and villages in other control units in the basin also have different levels of pollution reduction tasks.3.Taking the control sub-unit of the Jiangdong area of Dongpo District with uneven distribution of typical pollution emissions in the basin as an example,based on fairness and efficiency,a pollution optimization allocation model under multi-objective decision-making is established,using ideal point method and improvement based on elimination operator nondominated sorting genetic algorithm solves the optimal allocation amount.The results show that the Gini coefficient of the optimal allocation of pollution solved by the ideal point method is reduced by 0.04565 compared with the current situation,the overall reduction ratio of the control unit is 7801.83 tons,and the overall reduction ratio is 16.65%;the optimized allocation solved by the genetic algorithm shows that the pursuit of maximum environmental benefits,The overall pollution reduction task of the control unit is the lightest;when the pollution emission cost is the smallest,the overall pollution reduction task of the control unit is the heaviest;when the overall optimization is pursued,the overall pollution reduction ratio of the control unit is moderate,the overall reduction task is 5793.4 tons,and the reduction ratio is12.36% can be used as a phased pollution reduction target for towns and villages.