考虑指标协调性的湖泊富营养化评价模型

湖泊富营养化程度评价标准中同一评价指标的分级界点值差异很大,近似地呈现指数变化.基于该认识,提出了1个基于指标协调性的湖泊富营养化综合评价模型.对评价标准及待评湖泊监测值进行对数变换,改善了评价指标值的协调性,降低了评价系统的非线性化程度;在定义待评湖泊各监测指标与富营养化标准各级别之间距离测度的基础上,按评价指标协调性要求构造评价函数;鉴于评价标准为区问教的实际情况,采用区间数计算待评湖泊与各级标准的相对距离测度,并按距离测度值的大小进行湖泊富营养化状态分类.该模型建模思路清晰,物理意义明确,计算过程简捷,一组由5个湖泊组成的富营养化综合评价案例计算结果表明,评价结果符合实际.

Model for comprehensive evaluation of lake eutrophication considering coordination among indicators

There are big differences among the boundary data of the same indicator in the control standards of lake eutrophication. Values of boundary data can increase nearly exponentially. Based on the above consideration, a novel model is proposed for comprehensive evaluation of lake eutrophication. Logarithmic transformations are taken on both the boundary data of the indicators and the monitoring data of the lake to be evaluated, which improves the coordination among the indicators and decreases the non-linearity of the evaluation system. On the basis of defining relative distance measures between the eutrophication standard's boundary values and the monitored data of the lake, one evaluation function is constructed by taking account of the coordination among the indicators. Considering the practical situation of the control standard, interval number calculations are taken to find the relative distance measures and classification is done according to the relative distance measures' values to define the degree of lake eutrophication. This model is recommended for its clear modeling, tangible physical significance and simple calculations. Results of calculations for five example lakes show that the proposed model is concise, stable and practical.