基于潮汐变化特征的钱塘江河口环境需水

Environmental water demand of Qiantang estuary considering tide fluctuations

在河口排污不断增加而纳污总量控制滞后的局面下,即便在污染物达标排放的基础上,水质超标已成为普遍问题。钱塘江河口是典型的强潮河口,潮汐的周期性变化,尤其是半月潮汛的变化特征对河口水质影响显著。本文探讨了针对非恒定流的三种水质达标判断标准;建立了钱塘江河口大范围水质模型,反算了满足研究河段大潮期水质达标的环境需水为310m3/s。进一步根据钱塘江河口水质随潮变化的特点,研究了富春江电站不同泄流过程对研究河段水质达标的影响,得到大潮期多放30%、小潮期少放30%的泄流形式有利于降低污染物峰值浓度,提高水质达标时间。研究表明,结合潮汐15天变化特征的流量泄放过程,可减少约10%的环境需水,有效提高了水资源的利用效率。

Water quality deterioration is now becoming a widespread problem of most estuaries as an increasing amount of waste water is discharged while the control of total maximum load is lagging. Water quality of Qiantang estuary is significantly influenced by tidal fluctuations, particularly, by strong fortnightly tides. This paper puts forward three criteria of water quality evaluation for tidal estuaries and presents a simulation of environmental water demand 310m3/s of the study reach with a 2D water quality model. A further study on water quality control measures shows that by discharging 30% more in spring tide and 30% less in neap, the peak concentration is much depressed, the period of supply-demand balance is extended, and therefore the demand can be reduced by 10%