声学多普勒剖面仪对悬浮沉积物浓度的测量研究

Study of the measurement of suspended sediment concentration based on pulse-coherent acoustic doppler profiler observation

摘要: 为探讨声学多普勒剖面仪(PCADP)测量悬浮沉积物浓度(SSC)的可行性,将PCADP测量输出的声学后散射强度经衰减修正后,通过光学浊度计(OBS)标定转变为SSC.结果表明,SSC与后散射强度之间具有较好的相关性(R=0.74),用后散射强度测得的SSC平均相对误差为22.4%.为排除粒径变化对声学测量误差的影响,又对粒径变化不是很大的时段进行了分析,结果相关性有了较大提高(R=0.81),平均相对误差减小为18.9%.由此可见,PCADP能够达到专业SSC测量仪器的精度(20%~50%),满足沉积动力学研究的需要.

Abstract: In order to investigate the suitability of using pulse-coherent acoustic Doppler profiler(PCADP) to estimate suspended sediment concentration(SSC),the acoustic backscatter intensity was corrected for spreading and absorption losses,then calibrated with OBS,finally converted to SSC.The results show that there is good correlation with R equal to 0.74 between SSC and backscatter intensity.The mean relative error is 22.4%.Then the time span of little particle size variation was analyzed to exclude the influence of size variation.The correlation improves with R equal to 0.81 and the error decreases to 18.9%.It can be seen that PCADP estimating SSC can reach the requirement of professional instruments with the precision of 20% to 50%,and can meet the need of dynamics study.