闽江下游径流量和北港分流比变化及其对水龄的影响研究

利用闽江下游多年水文资料,分析了干流流量时空变化和北港分流比变化趋势,并借助EFDC模型研究水口水库下泄流量和北港分流比对闽江下游水体水龄的影响。分析表明:闽江干流径流量年际变化不均匀,北港分流比则经历了由小变大再变小的趋势。模拟的闽江水龄结果可知水龄与下泄流量成反比关系,北港分流比减小将增加北港水体交换时间,同时减少南港水体交换时间;水龄可以定量地描述污染物在北港河道的停留时间,为保障北港水源地水质安全,需要增大枯水期上游水口水库下泄流量和增大北港分流比。

Influence of runoff in downstream of Minjiang river and change of diversion ratio in Beigang on water age

The paper analyzed the temporal variation of main river discharge and the change trend of diversion ratio of Beigang by using hydrological data in downstream of Minjiang River.It used a three-dimensional environmental fluid dynamics code (EFDC) model to analyzed the effect of discharge and diversion ratio of Beigang on transport timescales (water age). The analysis result showed that annual flow of Minjiang is uneven and diversion ratio of Beigang is from small to big, then to small; there is a negative correlation between water age and river discharge. The decrease of diversion ratio will increase time of water body exchange of Beigang and will decrease that of Nangang. Water age can estimate time scales quantifying transport processes of dissolved substance for a spatially varying case. In order to protect water quality of water source areas at downstream of Minjiang, it is necessary to increase the freshwater discharge in Shuikou reservoir and the diversion ratio of Beigang during dry period.