滨江水体水环境容量计算研究

针对滨江水体感潮特性明显、水流运动复杂等特点,考虑污染物质输运过程平面分布的不均匀性,提出了基于非均匀分布系数的水环境容量计算方法;以镇江内江为研究区域,建立了二维水流水质耦合数学模型.通过对内江2004年4月及8月两个典型全日潮流场特征及相应污染物迁移扩散过程的数值模拟,建立了排污量与污染带响应关系曲线,求得内江洪、枯两季非均匀分布系数分别为0.18与0.25;对内江不同水位条件及不同典型年水环境容量进行计算.结果表明,内江维持水位对其水环境容量影响较大,洪季维持平均水位4m时的容量值约比1m时增加了33.5%;不同典型年,内江水环境容量相差也较大,丰水年容量值较平水年增加了110%,而枯水年则比平水年减少了32.8%;各年内总容量的84%主要分布在5月至10月.该方法运用非均匀分布系数综合体现了滨江水体水动力条件复杂及潮汐作用下污染物迁移扩散规律多变对水环境容量的影响.

Calculation of the water environment capacity for a waterfront body

Based on the tide fluctuations,complicated hydrodynamic structure and asymmetric pollutant migration,an asymmetrical coefficient-based calculation method was used to calculate the capacity of the water environment of a waterfront body.In this case,Neijiang of Zhenjiang city was taken as a research area and a 2-D hydrodynamic-water quality model was established.By using the typical daily data of April and August in 2004,the tidal current and the pollutant migration process were numerically simulated.The relationship between pollutants discharged and the pollution area was established,and asymmetrical coefficients for flood season and dry season were calculated(0.18 and 0.25,respectively).The data showed that the environmental capacity in Neijiang was significantly affected by the water level and the hydrological conditions.When the water level changed from 1 to 4 m,the capacity increased by 33.5%.Compared with a common-water year,the environmental capacity in a high-water year could be increased by 110% and in a low-water year,it could be reduced by 32.8%.At the same time,about 84% of the total capacity of the water environment in each year was mainly distributed in May to October.With the asymmetrical coefficient,the presented method reflects the effects of hydrodynamic conditions and the pollutant migration under the impact of tides,so it should be easily and widely useful.