三峡水库万州段岸边环境容量的计算与分析

岸边水环境容量特指在岸边侧向排污的方式下,污染混合区不超过允许污染范围情况下岸边水域所能容纳的最大污染物量。本文提出了一种计算岸边水环境容量的方法,该方法以数值模拟为基础,绘制出污染混合区范围与排污负荷的变化曲线;并根据江段岸边水域的控制目标,确定出该江段的岸边环境容量。本文将该方法应用于三峡水库万州段岸边水环境容量的计算,计算结果表明,随着三峡水库水位上升,流速变缓,岸边污染混合区的范围普遍增加,排污口的最大允许负荷量随之减小,同时,江段的岸边环境容量也会相应减小,为保证三峡水库的水质,应进一步控制三峡水库的污染来源。

Computation and analysis of environmental capacity in Wanzhou reach of Three Gorges reservoir

In this paper,a new method is presented for evaluating the water environmental capacity(WEC),which is defined as the maximum permitting mass loadings of the pollutant(MPMLP) from effluents around the received water body in the manner of side-discharge with no particularly harmful effect on beneficial uses.In this method,MPMLP is calculated via variation curves describing the relation of the scope of the mixing zone versus the mass loading of pollutant from the selected representative effluents,plotted based on the numerical results of the simulation of mixing zone by a non-horizontal multilayer model.The results of WEC are evaluated in the limit of satisfying the specified surface water criterion.The present method is applied to Three Gorges reservoir(TGR) for the evaluation of WEC in Wanzhou reach.The case study results show that Three Gorges Project will significantly expand the mixing zone and reduce both the value of NPMLP from the effluents and WEC because of the water surface leveling up and the water flow slowing down.Further measures are necessary for cutting down the mass loadings of pollutant for the protection of the water quality in TGR.