城镇河网水环境模拟及水质改善情景方案

Simulations of a water quality improvement for urban river networks

为寻求促进平原地区城镇河网水环境问题识别和水质改善的方法,以苏州市甪直镇河网为例,基于水文水质监测数据建立了相应的水环境模型,并将其应用于水质问题识别和水质改善方案研究中。甪直河网流动状态欠佳,长期平均流速小于0.02m/s的河道占河道总长度的63%、总水面面积的49%,不利于污染物迁移扩散,是导致该区域水质变差的主要原因。利用水环境模型对甪直河网的水文水质时空分布进行模拟分析,在此基础上制定出水系结构优化和水利调度强化2个水质改善方案。基于水环境模型的情景分析结果表明:水系结构优化方案能够有效促进生化需氧量BOD5和氨氮NH3-N这2类污染物的整体质量浓度水平降低。现场试验结果表明:水利调度强化方案能够有效地增强甪直河网流动性,实现以溶解氧DO质量浓度上升为表征的水质改善。

Water environmental data was used to develop a hydrodynamics-water quality coupled simulation model for the river network in Luzhi Town of Suzhou,China.The monitored and simulated water quality data show that about 63%of the river length and 49% of the area flows very slowly,with an average velocity always less than 0.02 m / s.The bad hydrodynamics status is identified as one of the reasons of bad water quality.Two plans were then developed to improve the river network structure and hydraulic engineering operations to improve the water environment.A scenario analysis based on the model shows that river network optimization can effectively reduce BOD5 and NH3-N.Field tests showed that the hydraulic engineering plan can effectively improve the hydrodynamic conditions of the river network and,thus,the water quality.