三峡水库整体一维水质数学模拟研究

Numerical simulation of water quality for the Three Gorges Project Reservoir

以三峡整个库区作为研究对象体,根据三峡水库河道型特点,开发了一维非恒定水流水质数学模型,利用稳定性比较好的四点隐格式有限差分法进行模型数值求解。以主要污染指标BOD5、DO为例,介绍了三峡水库一维水流水质数学模型的开发、研制过程。模型中充分考虑了三峡水库建成前后水流条件巨大变化对库区水流水质的影响,对主要水质模型参数,如污染物纵向离散系数、有机污染物衰减系数和大气复氧系数等建立了与水流条件相关的经验关系式,建立的数学模型经过三峡库区江段长河段水文水质和污染源同步观测资料验证,具有较高的模拟精度,可为预测三峡水库水流水质总体变化趋势提供技术支持。

The 1-D unsteady model based on finite difference method with fourpoint implicit scheme simulating the water flow and water quality in the reservoir of Three Gorges Project is established. The major indices of water quality including 14 items are investigated. The effects of significant change of flow condition in the reservoir due to impounding are taken into account. The coefficients of the model including the longitudinal dispersion coefficient, decay rate of BOD5 and atmospheric reaeration rate of DO etc. are established empirically. The model is applied to predict the variation trend of water quality in the reservoir.