Three-dimensional unstructured-mesh eutrophication model and its application to the Xiangxi River,China

作     者：Jian Li Danxun Li Xingkui Wang 

作者机构：State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University Beijing 100084 China 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2012年第24卷第9期

页      面：1569-1578页

核心收录：

学科分类：08[工学] 0815[工学-水利工程] 081502[工学-水力学及河流动力学] 

基　　金：supported by the National Natural Science Foundation of China (No. 50823005) 

主　　题：unstructured-mesh model algal bloom phytoplankton Xiangxi River 

摘      要：The Xiangxi River is one of the main tributaries in the Three Gorges reservoir, with the shortest distance to the Three Gorges Project Dam. Severe and frequent algal bloom events have occurred frequently in the Xiangxi River in recent years. Therefore, the current study develops a three-dimensional unstructured-mesh model to investigate the dynamic process of algal bloom. The developed model comprises three modules, namely, hydrodynamics, nutrient cycles, and phytoplankton ecological dynamics. A number of factors, including hydrodynamic condition, nutrient concentration, temperature, and light illumination, that would affect the evolution of phytoplankton were considered. Moreover, the wave equation was used to solve the free surface fluctuations and vertical Z-coordinates with adjustable layered thicknesses. These values, in turn, are suitable for solving the algal bloom problems that occurred in the fiver style reservoir that has a complex boundary and dramatically changing hydrodynamic conditions. The comparisons between the modeling results and field data of years 2007 and 2008 indicate that the developed model is capable of simulating the algal bloom process in the Xiangxi River with reasonable accuracy. However, hydrodynamic force and external pollution loads affect the concentrations of nutrients, which, along with the underwater light intensity, could consequently affect phytoplankton evolution. Thus, flow velocity cannot be ignored in the analysis of fiver algal bloom. Based on the modeling results, building an impounding reservoir and increasing the releasing discharge at appropriate times are effective ways for controlling algal bloom.