基于不确定性分析框架的动态环状河网水质模型——以温州市温瑞塘河为例

Dynamic water quality model for looping river network based on the framework of uncertainty analysis:A case study of Wenruitang River Basin

以温州市温瑞塘河为背景,基于不确定性分析的框架,开发了动态环状河网水质模型。用HSY(Hornberger,SpearandYoung)算法作水质参数的不确定性分析,求得模型参数的空间分布,从而提高模型使用的可靠性、降低决策的风险度。模型由水量子模型及水质子模型两部分组成:水量子模型采用圣维南方程并用四级解法求解;水质子模型采用CSTR(ContinuouslyStirredTankReactor)模型的机理,并结合环状河网特征作了修正,由于只需解常微分方程,因而避免了矩阵求解,显著提高了计算效率,使得用HSY算法进行不确定性分析成为可能。模型选取温州市温瑞塘河流域的鹿城区河网进行了首次应用,用HSY算法率定水质参数并讨论了参数的不确定性。对参数率定结果进行验证,结果比较理想。最后简要讨论了参数不确定性传递。

Taking the Wenruitang river system as a case study, a dynamic water quality model for looping river networks is developed based on the framework of uncertainty analysis. The distribution of water quality parameters can be got by the HSY (Hornberger, Spear and Young) algorithm based on the uncertainty analysis, which can improve the credibility of the model simulation and reduce the risk of the decision making. The model consists of two sub-models, i.e., the hydrodynamic and the water-quality models. The hydrodynamic sub-model is based on the Saint Venant equations and the four-step numerical method is applied to their solutions. The water quality sub-model is established from the CSTR concept, yet with essential amendments in accordance with the requirements of looping river networks. Only ordinary differential equations need to be solved, and the matrix solving can be avoided so that the calculation efficiency is greatly improved, which makes HSY algorithm possible to be used. The model is firstly applied to Lucheng river network, which is the key part of Wenruitang river system in Wenzhou City. HSY algorithm is used to calibrate the model parameters, and the parameter's uncertainty is analyzed. The model is verified and the results are relatively ideal. Finally, the uncertainty transferred to the simulation results due to the parameter's uncertainty is briefly discussed.