关键词: 水生态功能分区, 区间灰数, 多目标, 管控措施, 灰色NSGA-II

Abstract: With the implementation of a series of national ecological environment strategies such as the Yangtze River protection strategy, the Yellow River Basin ecological protection and high-quality development, it has become a hot spot to carry out systematic and comprehensive research on the management of water ecological environment from the river basin level. The water ecological function zoning management is a new management and control mode to implement the comprehensive management, system management and source management of mountains, rivers, forests, fields, lakes, grasses and sands. With the deepening of the management and control of water ecological function zoning, the management and control measures have gradually changed to the direction of comprehensive management, system management and source management. How to take into account multiple objectives such as environmental governance, economic development, and social equity, and optimize the combination of various engineering and non-engineering measures such as source control and pollution interception, water quality purification, and endogenous treatment to form a control plan has gradually become an important issue in the management and control of water ecological function zoning.
The water ecological function zoning is defined according to the hydrological and geographical characteristics, which is inconsistent with the administrative division, and the basic data of the economic, social and ecological environment of the zoning are incomplete. Therefore, it is difficult to accurately measure the cost and benefit of the zoning control measures. They can only rely on some existing data and expert experience, as well as information obtained through various channels to estimate the range of relevant parameters. However, in the actual governance process, the cost, benefit and other parameter values of various control measures have a unique and determined value. This is consistent with the characteristics of the gray number, that is, the true value of the data is unique, but there is a certain gray range in the information background dependent on the true value.
In view of the above problems, firstly, the expression forms of parameter uncertainty in the process of management and control are analyzed. Based on the characteristics of grey number, an optimal management and control model including two kinds of objectives and six kinds of management and control measures is constructed with the constraint of zoning management and control assessment objectives. Then, based on the NSGA-II algorithm framework, the comparison rules based on the interval grey number kernel are combined with the non-dominated sorting to establish the grey non-dominated sorting method. When the individuals at the same level cannot be compared, the comparison rules of the interval grey number gray level are combined with the crowding distance operator to establish the gray crowding sorting method. The two-stage sorting method is combined to obtain the solution method of the grey parameter multi-objective programming model, namely the grey NSGA-II algorithm. Finally, this model and algorithm are applied to the typical zoning of water ecological function in Taihu Lake Basin of Jiangsu Province, and the control scheme is optimized and analyzed in combination with social and economic conditions to solve the problem of optimal control of regional water ecological environment under uncertain conditions, so as to provide reference for multi-objective control decision-making of related zoning.

Key words: water ecological function zoning; interval grey number; multi-objective; control measures; grey NSGA-II