基于水动力-水质模型的湖库纳污能力量化

Quantization of Pollutants Bearing Capacity in Lakes or Reservoirs Based on Hydrodynamic-Water Quality Model

"湖库纳污红线的核定"是我国最严格水资源管理制度中三大核心内容之一,也是保障城市供水安全、水资源可持续利用的关键问题之一。我国现行纳污能力的计算往往采用对稳态水质模型的解析求解,但无法获得不同来水、排污和内源污染等多种因素影响下水体纳污能力的时空动态变化。水动力-水质模型能够反映湖库水质和外部营养负荷之间的定量关系,可精细模拟水质指标在库区内的时空变化过程。基于EFDC模型,以深圳市重要饮用水源地——石岩水库为例,构建了水库三维水动力-水质模型,动态模拟了水位和水质的时空变化;并按照水功能区目标要求,探讨了该水库典型年的纳污能力的季节性变化。结果表明:EFDC模型能够准确模拟石岩水库水动力和水质要素的变化过程,水位、COD_(Mn)和NH_3-N模拟的相关系数达到了0.97、0.60和0.90;基于构建的三维水动力-水质模型,考虑到排放口位置和条件、水质的时空分布特点、底泥释放等实际因素,计算得到石岩水库2011年COD_(Mn)和NH_3-N纳污能力分别为2 158、511 t/a;纳污能力的季节性差异很明显,夏季和秋季较大,春季和冬季较小。研究成果可为我国饮用水源地水质管理和污染控制提供科学依据,也可为我国最严格水资源管理制度的实施提供一定的参考和借鉴。

The approved of the red line of lakes and reservoirs pollutants bearing capacityis one of the three core elements of the most stringent water management system in China, and also one of the key issues of protecting the security of water supply in cities and the sustainable use of water resources. Hydrodynamic and water quality model can quantitatively reflect the response of water quality to nutrient loads, and simulate temporal and spatial variation of water quality. In this paper, based on EFDC model, taking Shiyan Reservoir, an important source of drinking water in Shenzhen City, for an example, a three-dimensional hydrodynamic and water quality model in the reservoir was built to dynamically simulate the temporal and spatial variation of its water level and water quality. Further-more ,in accordance with the objectives and requirements of water function area, the seasonal variation of pollutants bearing capacity of the reservoir in a typical year is discussed. The results showed： （ 1 ） EFDC model could accurately simulate the hydrodynamic and water quality process in Shiyan Reservoir, and the correlation coefficient of the simulated water level, C0DMn and NH3 - N indexes reached 0. 97 , 0. 60 and 0. 90; （2） Based on the three dimensional hydrodynamics and water quality model, considering some practical factors such as the outfall location and conditions, temporal and spatial distribution of water quality, sediment release and so on, the calculated security pollutants bearing capacities of C0DMn and NH3 - N in the Shiyan Reservoir were 2 158 tons and 511 tons in 2011. And the seasonal variation of pollutants bearing capacity was very obvious ; it was large in summer and autumn and small in spring and winter. The research results can provide a scientific basis for water quality management of drinking water sources and pollution control, as well as provide a certain reference for the implementation of the most strict water resources management system in China.