随机误差对海水水质环境评价影响探讨

Influence of stochastic error on seawater environment evaluation

海水环境评价既存在自然的随机性,又有评价的模糊性。以往评价大多只考虑实测指标的物理权重的影响,很少考虑各指标在实测过程中不可避免的随机误差的影响。本文应用最大熵原理配合对应的约束条件推导出水环境评价实测指标的概率分布为正态分布,以蒙特卡罗随机模拟法构造算例,讨论随机误差对海水环境评价的影响,结果表明:随机误差的影响不容忽视,有时能直接改变海水环境的评价结果;当各指标的实测值精度有差异,尤其是差异较大时,随机误差权重对于海水的评价结果的影响也随之加大,此时,评价结果主要决定于某(几)项浓度相对较大的评价指标和随机误差较小的评价指标。

There are the natural randomness and fuzzy in the environmental evaluation of sea water. The appraised influence of physical weights was mostly considered for the surveying index in the past, the influence of the unavoidable random error was seldom considered in the course of every surveying index. The principle of maximum entropy and Monte Carlo method are applied to study the influence of stochastic error on the seawater environment evaluation. First, the least biased prior probability distribution of observed index under the given constraint condition is derived using the principle of maximum entropy. Then the influence of stochastic error the on seawater environment evaluation is investigated by Monte Carlo method. The result shows that the influence of stochastic error on the seawater environment evaluation can not be neglected, on the evaluation grade sometimes. Furthermore, if the observation error is remarkable, the influence would be increased correspondingly. In that case the evaluation result mainly depends on some indexes with minimum stochastic error and relatively bigger content.