河流水质模型及存在问题

介绍了河流水质模型的基本思想和建立方法,主要涉及控制方程、流体力学方程、迁移方程和转化方程等.论述了现有河流水质模型存在的问题,主要涉及模型的近似性、模型的调整和验证、以及模型的预测性等.一维流动的假定,使计算所得的污染物的浓度,往往远低于河流中的最高浓度.由于模型以BOD作为状态变量,以及对SOD的底栖生物需要量和对细菌降解系数的考虑方法等,因而它不能完全满足质量守恒.为了使模型适用于某一特定河流系统 ,必须根据具体条件对模型参数进行调整.缺乏必要的现场数据对模型进行可靠的调整和验证,是模型应用中的突出问题.在一些特殊情况下,模型的预测能力会变得很差.

River water quality models and the problems related to them

The basic approach to the river water quality models is introduced in this paper. The particular attention is paid to governing equations, hydrodynamics, transport processes and conversion processes. The problems related to the present river water quality models are pointed out. They exist mainly in approximations, calibration and verification, and predictive ability. The treatment of the river as an one-dimensional system makes the result as the prediction of average river concentrations that may be much less than those observed in the river. Mass balances cannot be closed for the use of BOD as a state variable, the treatment of SOD for benthic demands and the degradation coefficient for the pelagic bacteria. The calibration of the model to the specific river is a key step in model use, and the lack of adequate data for model calibration and verification is the main problem. The model has poor predictive ability in some particular cases.