三峡水库香溪河库湾不同异重流下水温分层模式研究

三峡水库蓄水后支流库湾水体的水动力条件发生变化,水温在垂向上的分布也呈现出了不同模式。为了分析不同类型的倒灌异重流条件下水体的水温分布情况,对香溪河库湾不同断面的水温进行原位监测,并构建库湾水体的水温水动力数学模型(CE-QUAL-W2)。研究结果表明:水库正常运行的不同时期,香溪河库湾水体的主要水动力条件和水温分布结构均不同,在水库运行时的泄水期,库湾水体水动力主要为表层倒灌异重流,水温呈现传统的分布模式;在水库汛期低水位运行时,库湾水体水动力主要为中层倒灌异重流,水温呈“双混斜”式分布;在水库蓄水期,库湾水体水动力主要为底部倒灌异重流,水温呈“半U”型分布。研究成果可为揭示香溪河水流水温特性、营养盐迁移及水华预测预报提供相关的理论支持和技术支撑。

Model of Water Temperature Stratification in Xiangxi Bay of the Three Gorges Reservoir with Different Density Currents

After the impoundment of the Three Gorges Reservoir,the hydrodynamics of branch bay together with the distribution of water temperature in vertical direction has changed.To investigate into the distribution of water tem perature in the presence of different types of density current,we monitored the water temperature in-situ in different sections of the Xiangxi Bay,and established a hydrodynamic model (CE-QUAL-W2).We conclude that the main hydrodynamic conditions and water temperature distribution in normal periods of reservoir operation vary correspondingly:in discharge period,backward density current at surface layer is the major hydrodynamic pattern with conventional water temperature distribution;in flood season at low water level,backward density current at middle layer is the major hydrodynamic pattern,with water temperature distributes in double mixing-thermocline type;while in storage period,backward density current at bottom layer is the dominant hydrodynamic pattern,with the water temperature distributes in a half-U shape.The research results offer theoretical and technical support for revealing the water temperature distribution and nutrients transport as well as forecasting water bloom in the Xiangxi Bay.