In order to simulate the characteristics of hydrodynamic field and mass transport processes in the Yuqiao Reservoir （YQR）, a 2-D coupled model of hydrodynamics and water quality was developed, and the water-quality ...In order to simulate the characteristics of hydrodynamic field and mass transport processes in the Yuqiao Reservoir （YQR）, a 2-D coupled model of hydrodynamics and water quality was developed, and the water-quality related state variables in this model included CODMn, TN and TP. The hydrodynamic model was driven by employing observed winds and daily measured flow data to simulate the seasonal water cycle of the reservoir. The simulation of the mass transport and transformation processes of CODMn, TN and TP was based on the unsteady diffusion equations, driven by observed meteorological forcing and external loadings, with the fluxes form the bottom of reservoir and the plant photosynthesis and respiration as internal sources and sinks. A finite volume method and Alternating Direction Implicit （ADI） scheme were used to solve these equations. The model was calibrated and verified by using the data observed from YQR in two different years. The results showed that in YQR, the wind-driven current was an important style of lake current, while the concentration of water quality item was decreasing from east to west because of the external pollutant loadings. There was a good agreement between the simulated and measured values, with the minimal calculation error percent of 0.1% and 2.6% and the mean error percent of 44.0% and 51.2% for TN and TP separately. The simulation also showed that, in YQR, the convection was the main process in estuaries of inflow river, and diffusion and biochemical processes dominate in center of reservoir. So it was necessary to build a pre-pond to reduce the external loadings into the reservoir.展开更多
水生植被分布情况、结构和演变趋势对湿地生态环境变具有重要的指示意义和科学研究价值。基于Sentinel-2遥感数据,综合应用光谱信息、水体植被指数、最佳指数法(Optimal Index Factory,OIF)计算的纹理特征,结合随机森林分类法,构建特征...水生植被分布情况、结构和演变趋势对湿地生态环境变具有重要的指示意义和科学研究价值。基于Sentinel-2遥感数据,综合应用光谱信息、水体植被指数、最佳指数法(Optimal Index Factory,OIF)计算的纹理特征,结合随机森林分类法,构建特征优化后的随机森林水生植被提取模型,对于桥水库进行水生植被提取。结果显示:该方法能有效的提取出水生植被,总体精度为93.22%,Kappa系数为0.91。进一步与最大似然和支持向量机(SVM)方法进行对比分析,结果表明本算法的总体精度分别提高了19.96%、8.53%,Kappa系数分别提高了0.25、0.11。基于水生植被全年提取结果,分析了于桥水库的水生植被年内变化,发现于桥水库水生植被在五月份最繁盛,随后逐渐消减,直至十月份基本消亡。实验表明:特征优化后的随机森林分类法在Sentinel-2影像水生植被提取中具有较好的适用性。展开更多
基金the National Basic Research Program of China (973 Program, Grant No. 2006CB403400)the National Natural Science Foundation of China (Grant Nos. 50679088, 90610037).
文摘In order to simulate the characteristics of hydrodynamic field and mass transport processes in the Yuqiao Reservoir （YQR）, a 2-D coupled model of hydrodynamics and water quality was developed, and the water-quality related state variables in this model included CODMn, TN and TP. The hydrodynamic model was driven by employing observed winds and daily measured flow data to simulate the seasonal water cycle of the reservoir. The simulation of the mass transport and transformation processes of CODMn, TN and TP was based on the unsteady diffusion equations, driven by observed meteorological forcing and external loadings, with the fluxes form the bottom of reservoir and the plant photosynthesis and respiration as internal sources and sinks. A finite volume method and Alternating Direction Implicit （ADI） scheme were used to solve these equations. The model was calibrated and verified by using the data observed from YQR in two different years. The results showed that in YQR, the wind-driven current was an important style of lake current, while the concentration of water quality item was decreasing from east to west because of the external pollutant loadings. There was a good agreement between the simulated and measured values, with the minimal calculation error percent of 0.1% and 2.6% and the mean error percent of 44.0% and 51.2% for TN and TP separately. The simulation also showed that, in YQR, the convection was the main process in estuaries of inflow river, and diffusion and biochemical processes dominate in center of reservoir. So it was necessary to build a pre-pond to reduce the external loadings into the reservoir.
文摘水生植被分布情况、结构和演变趋势对湿地生态环境变具有重要的指示意义和科学研究价值。基于Sentinel-2遥感数据,综合应用光谱信息、水体植被指数、最佳指数法(Optimal Index Factory,OIF)计算的纹理特征,结合随机森林分类法,构建特征优化后的随机森林水生植被提取模型,对于桥水库进行水生植被提取。结果显示:该方法能有效的提取出水生植被,总体精度为93.22%,Kappa系数为0.91。进一步与最大似然和支持向量机(SVM)方法进行对比分析,结果表明本算法的总体精度分别提高了19.96%、8.53%,Kappa系数分别提高了0.25、0.11。基于水生植被全年提取结果,分析了于桥水库的水生植被年内变化,发现于桥水库水生植被在五月份最繁盛,随后逐渐消减,直至十月份基本消亡。实验表明:特征优化后的随机森林分类法在Sentinel-2影像水生植被提取中具有较好的适用性。
