珠江口磨刀门水道盐度变化对水文气象要素的频率响应特征

Frequency response characteristics of salinity change to hydro-meteorological elements in Modaomen waterway of Pearl River Estuary

以2010年11月-2011年3月磨刀门水道挂定角、联石湾、竹排沙、平岗和竹银5个测站的盐度、马口水文站流量、三灶站潮位和竹银站的主流向风速为基本数据,应用偏相干谱估计方法分析了各测站盐度变化对潮汐、流量和风的频率响应。经验诊断分析结果表明:1)马口站入海径流存在准1日、半日、1/4日和1/3日等显著的潮致振荡周期;2)各测站盐度变化与潮汐主要振荡周期并不一致,沿磨刀门水道向上游,潮汐对盐度变化的影响递减,竹银站盐度可作为潮汐直接作用下咸潮上溯的平均上限位置;3)消除潮汐和径流的影响后风对盐度变化的作用明显加强;4)各测站盐度变化对潮汐、流量与风的响应过程存在时间超前或滞后但无特定规律,说明磨刀门水道盐度变化过程十分复杂。

Frequency response of salinity changes of five stations（ Guadingjiao, Lianshiwan, Zhupaisha, Pinggang, and Zhuyin） to the tides（ Sanzao）, river discharges（ Makou） and mainstream direction wind speeds（ Zhuyin） along the Modaomen waterway of the Pearl River Estuary was analyzed by using the data between November, 2010 to March, 2011 and the partial coherency spectral estimation. The empirical diagnostic analysis results showed： 1） There were significant tideinduced oscillation cycles of the runoff discharged at Makou station with the quasi diurnal, the semidiurnal, a quarter of the day and a third day; 2） The oscillation period of salinity changes of five stations did not agree with the main tidal oscillation period. And the effect of tides on the salinity changes decreased progressively upstream along the Modaomen waterway. The salinity of Zhuyin station could be the average limit position of saltwater under the direct tidal action; 3） The wind effect on salinity changes significantly strengthened after eliminating the influence of tide and runoff; 4） The response of salinity at each station to the tides, runoff and wind processes existed temporal lead or lag with no specific rules, which indicated that the salinity changes in Modaomen waterway were very complicate.