基于水环境改善的城市湖泊群河湖连通方案研究

Interconnected river system network scheme of urban lake group based on water environment improvement

河湖水系连通作为水资源调配、水生态修复与改善的重要手段,已成为江河湖泊治理工作的重点之一。河湖水系连通方案的选择和连通效应的评估直接关系到连通工程对湖泊水动力和水环境的改善效果,但目前缺乏对水系连通后河湖水动力和水质的综合评估体系。以汤逊湖湖泊群为研究对象,构建二维水动力水质数学模型,选取NH3-N、TN和TP作为水质指标,模拟不同连通方案下汤逊湖湖泊群的流场及水质变化情况,结合水动力、水质和经济社会三个方面的评价指标建立综合评价体系,对各连通方案下湖泊群的改善效果进行评估。研究结果表明:引水后湖泊水体流动性有了很大的改善,河湖连通工程能够在短时间内达到改善湖泊水质的目的,但随着引水时间的增长,改善率逐渐减小。通过对比五种连通方案发现,方案五对水动力和水质的改善都取得了最显著的效果,且能够带来最大的引水效益。

The Interconnected River System Network（IRSN）, which plays a significant role in water resource allocation, water ecological restoration and water quality improvement, has become a key part of the urban lake management. The optimization of IRSN scheme and the evaluation of IRSN effects have a direct influence on the improvement of hydrodynamics and water quality. However, no comprehensive evaluation system has been built up to evaluate the hydrodynamics and water quality of the connected lakes. In this paper, a two-dimensional mathematical hydrodynamics and water quality model was built, and indexes including NH3-N,TN and TP were chosen as the water quality indexes to simulate the flow field and water quality of the Tangxun Lake group under different IRSN schemes. In addition, a comprehensive evaluation system based on evaluation indexes from the aspects of water hydrodynamics, water quality and socioeconomics was established to evaluate the IRSN effects of the Tangxun Lake group. The results showed that the fluidity of lakes improved greatly after the water diversion.The IRSN project can improve water quality of the lakes in a short time, while the improvement rate decreased gradually as the water diversion time increased. The comparison of these five schemes mentioned in this paper indicated that the fifth scheme（concurrent diversion from Donghu Lake and Liangzi Lake） can achieve the most obvious improvement in both hydrodynamics and water quality and generate the most economic benefits.