基于ADV的三峡水库瞬时含沙量测量研究

ADV-based measurements of instantaneous suspended sediment concentrations in the Three Gorges Reservoir

利用ADV在三峡水库淤积较为严重的忠县和奉节河段实施含沙量测量,建立了瞬时含沙量的声学反演方法。ADV声波强度信号通常受局部毛刺和高频噪声的影响,提出先用小波分析过滤高频噪声、再用相空间密度法剔除毛刺的声波信号处理方法。实测资料率定表明含沙量和声波强度在双对数坐标系下呈线性关系,其斜率和截距均为泥沙中值粒径的函数,从而得到了瞬时含沙量反演公式。据此计算的泥沙扩散通量与雷诺应力具有较强的正相关性、含沙量标量谱遵循Obukhov-Corrsin的-5/3次方规律,表明本文提出的瞬时含沙量反演方法可行。

Field ADV measurements of suspended sediment concentrations have been taken in the Zhongxian and Fengjie reaches of the Three Gorges Reservoir, which are suffering from serious sediment deposition. From these field data, we have developed an inversion method for instantaneous sediment concentration. ADV acoustic signals are usually contaminated by spikes and high-frequency noises. To despike the signals, this method adopts wavelet analysis to filter out their high-frequency noises, and then processes them using a phase-space density method. Calibration of sediment concentration versus acoustic intensity in double logarithmic coordinates shows a linear relationship whose slope and intercept are both functions of particle diameter, thus providing an inversion formula for instantaneous sediment concentration. Calculations using this formula reveal that turbulent sediment fluxes are closely related to the Reynolds stresses and the scalar spectrums of sediment concentrations follow the Obukhov-Corrsin law of-5/3 power. The results indicate that our new inversion method for instantaneous sediment concentration is feasible and effective.