三峡水库支流库湾分层异重流成因定量化分析

Spatial-temporal Distribution and Threshold of Density Flow in the Tributaries of the Three Gorges Reservoir

淡水水体中,温度和浊度的差异产生密度差,从而形成异重流的重要因素。为探明香溪河库湾分层异重流时空分布差异因素,系统分析了香溪河库湾全年水温、浊度时空变化特征,并进行了定量化计算。结果表明:香溪河库湾异重流主要由水体之间的温差和浊度差引起;浊度差是汛期异重流发生的主要原因,CJXX、XX00泥沙含量对水体密度的影响较水体温度更为显著,泥沙含量对水体密度的贡献程度最大为96%,温度差是非汛期库湾异重流发生的主要原因,水温贡献程度在各月均超过95%;水体浊度差ΔZD与温度差ΔT的比值在167.27与357.27之间时,浊度差产生的泥沙含量差Δρ_(S)与温度差产生的水体密度差Δρ_(T)相等,两者对水体密度的影响相当;比值小于167.27时,温度差对水体密度贡献显著;比值大于357.27时,泥沙含量对水体密度的贡献显著。

In fresh water,the difference of temperature and turbidity is an important factor for density difference and density flow.In order to find out the spatial-temporal differences and influencing factors of density flow in Xiangxi Bay,based on the monthly hydrodynamic monitoring data of Xiangxi Bay in 2018,hydrodynamic processes such as water temperature and turbidity are analyzed and the quantitative calculation is carried out.The results show that density flow is mainly caused by the temperature difference and turbidity difference in Xiangxi Bay.In the flood season,turbidity difference is the main reason for density flow in the flood season,and sediment concentration of CJXX and XX00 has a more significant effect on water density than temperature,the contribution rate,which is caused by sediment concentration on water density,is up to 96%.The contribution rate caused by water temperature difference to water density,is more than 95%in each month.When the ratio(The ratio of turbidity differenceΔZD to temperature differenceΔT)is between 167.27 and 357.27,the sediment concentration differenceΔρ_(S)generated by turbidity difference is equal to the water density differenceΔρ_(T)generated by temperature difference,both of them have the same effect on the water density.When the ratio is less than 167.27,the contribution caused by temperature difference to water density,is significant.When the ratio is more than 357.27,the contribution caused by sediment concentration difference to water density,is significant.