珠江三角洲典型复杂河网区水系连通及调度研究

Study on the connection and regulation of typical complex river network in the pearl river estuary

【目的】河流水系是城市重要的资源和环境载体,水系连通是保证河流系统健康完整和功能正常发挥的重要条件,而活水调度是提高水体流动性和改善水生态环境的重要手段。水系连通指标是分析和评价连通性的关键,【方法】针对珠江三角洲地区的复杂河网,首次提出将往复流河段和断头涌河段长度占比纳入水系连通评价指标体系,分析研究典型区域水系现存问题,提出水系连通与调度方案,采用数学模型评估方案效果,研究珠江三角洲复杂河网水系连通与活水调度工程问题。【结果】结果显示:现状良安水系水动力条件较差,存在往复流和水体交换周期长等问题,水质污染严重,通过清淤疏浚、水系连通和引水工程调度活水,使往复流变为单向流,将现状15.3 d的河道平均换水周期最小缩短至7.3 d,河道现状流速0.021 m/s最大增加至0.124 m/s,区域的水动力条件和区域水质得到明显改善。【结论】结果表明:珠江三角洲城市化程度较高地区的河涌常存在有复流河段和断头涌河段影响河道的水质,有针对性地提出水系连通评价指标体系,并采取合适的清疏引水工程调度等措施,加强水系内部循环,可以改善水系的水质,提升水系综合治理的效果。研究结果可为珠江三角洲复杂河网区水环境问题改善与解决提供典型案例参考。

[Objective]River water system is an important resource and environmental carrier for cities,and water system connectivity is an important condition to ensure the health and integrity of the river system and normal functioning of river system.The regulation of live water is an important means to improve the mobility of water and the ecological environment of water,and the water system connectivity index is the key to analyzing and evaluating connectivity.[Methods]In view of the complex river net-work area of the Pearl River Delta,the proportion of the length of the reciprocating river reach and the cutoff river reach is included in the evaluation index system of water system connectivity for the first time.The existing problems of water system in typical re-gions are studied and analyzed,and the scheme of water system connection and operation is proposed.The effect of the scheme is e-valuated by mathematical model,and the engineering problems of water system connection and operation of complex river network in the Pearl River Delta are studied.[Results]The result show that the current Liang′an water system has poor hydrodynamic condi-tions,with problems such as reciprocating flow and long water exchange cycles.Water quality pollution is severe.Through dred-ging,water system connectivity,and water diversion engineering scheduling,the reciprocating flow is transformed into unidirection-al flow,reducing the average water exchange cycle of the current 15.3 d river to 7.3 d at a minimum,and increasing the current flow rate of the river from 0.021m/s to 0.124m/s at a maximum.The hydrodynamic conditions and water quality in the region have been significantly improved.[Conclusion]The result show that for the rivers in the highly urbanized areas of the Pearl River Delta,reciprocating river reach and the cutoff river reach often affect the water quality of river network.The targeted evaluation index sys-tem of water system connectivity is proposed,and appropriate measures such as the regulation of water diversion projects are taken to strengthen the internal circulation of the water system,which can improve the water quality of the water system and enhance the effect of comprehensive treatment of the water system.The study can provide a typical case reference for the improvement and solu-tion of water environment problems in the complex river network area of the Pearl River Delta.