Reynolds stress and turbulence estimates in bottom boundary layer of Fall of Warness

A broadband acoustic Doppler current profiler (ADCP) moored on the seabed at 42 m depth has been used to observe the mean and turbulent flow components in the tidally energetic Fall of Warness channel over two tidal cycles. The Reynolds stress has been estimated from the difference in variance between the along-beam velocities of opposing acoustic beams. Near bed stress at 2.63 m above seabed (mab) exceeds 7.5 Pa at the time of mean flow (speed of ~ 1.3 m s^− 1) while the ebb stresses are limited to ~ 3.31 Pa during the peak ebb, mean, flow of ~ 1.3 m s^− 1. The production of turbulent kinetic energy (TKE), P was found to be negative below 2 × 10^− 9 W m^− 3 and up to 6 × 10^− 4 W m^− 3 was estimated during flood flows and decreasing to 3 × 10^− 4 W m^− 3. The TKE dissipation rate ε was estimated by inertial dissipation method (IDM) with the greatest value of 2.43 × 10^− 2 W m^− 3 observed near the seabed around maximum ebb, falling to 5.75 × 10^− 5 W m^− 3 around slack water. The comparison between P and ε was performed by calculating individual ratios of P corresponding to ε using a bootstrap resampling technique. The study shows that the ratio ε/P averaged over whole flood and ebb were found to be ~ 0.4138 and ~ 0.4177, respectively, indicating that production exceeded dissipation. The uncertainties in Reynolds stress estimates due to instrument noise were found to be 3 × 10^− 4 Pa while 4.52 × 10^− 2 Pa can be attributed to the uncertainties due to the increase in the flow-related component.     

钢铁材质浮标对ADCP水文监测系统流量测验精度的影响

针对钢铁材质浮标的ADCP水文监测系统内置罗经受船磁力影响,导致流向测验出现偏差的问题,通过2009—2011年徐六泾水文站定线比测大、中潮水文测验的实测资料,分析采用垂直于断面的方位角作为流向(流向不修正)和采用断面各垂线实测平均流向作为流向(流向修正)两种情况下钢铁材质浮标对ADCP水文监测系统流量测验精度和流量、潮量计算的影响。结果表明:无论是否修正流向,计算得到涨落潮流量、潮量以及全潮下泄潮量和走航式ADCP定线比测的实测资料相比,误差均较小,精度都很高;在流量和潮量计算时,可以对钢铁材质浮标ADCP流向不做修正。     

Comparison under controlled conditions between multi-frequency ADCPs and LISST-SL for investigating suspended sand in rivers

This paper aims to investigate the possibility and limits of using the laser device LISST-SL to calibrate and validate the multi-frequency acoustic method for assessing the concentration and grain size of suspended sand in rivers by using Acoustic Doppler Current Profilers (ADCPs). Over the last few decades, the methods for investigating suspended sediment using Acoustic Backscattering (ABS) have been gaining increasing acceptance for riverine applications. ABS allows indirect quantification of the suspended sediment using non-intrusive measurements with high temporal and spatial resolution from a moving boat, with a range of several metres. Despite the advancement of these techniques, the use of ABS usually implies calibration and validation in the field, which can be performed by comparing echo recording by ADCP to data from water samples. Sampling and analysis of water samples noticeably increase the campaign cost and limits the reliability of the calibration because of the time and spatial averaging involved in physical sampling. In the present work, the LISST-SL suited to river applications was tested to provide matching data in one point for the validation of ADCP methods in future field work. To this end, laboratory tests were conducted utilising two ADCPs working at 1200 and 600 kHz frequencies and studying the same water volume that was concurrently being analysed by the laser device. Rapid injections of sand (median grain size: 130–250 μm) produced average concentrations of 100–1000 mg/L in a 0.25-m/s-fast and 1.7-m-deep flow. Echo records at the two frequencies were compared to the mean grain size and concentration measured via laser diffraction. Although noticeable differences between the acoustic and laser assessments of concentration were due to (1) inappropriate sampling of LISST-SL at low flow velocity and (2) investigation scarce resolution with respect to actual gradients, the corresponding mean sizes were well correlated.     

H-ADCP在流域引江济太工作中的实践

介绍了声学多普勒流速剖面仪（ADCP）的主要工作原理,总结了太湖流域引江济太调水工作的需要,以水平式ADCP（H-ADCP）系统在苏州望亭水文站中的应用为例,对比分析了2009年引水、排水期间H-ADCP和人工监测的数据,总结了H-ADCP的使用特点,比测分析结果说明ADCP测流数据合理准确,可为今后防汛、水资源管理信息化建设提供借鉴。     

ADCP在冬季测流中的应用

介绍了ADCP的优点及测量原理。用ADCP有效地解决了某水文站断面与河流流向不垂直及冬季测流的问题。结果表明:①如果不进行流量偏角修正,则流速仪法所测数据同ADCP法测得的数据接近;②流速仪法在测流过程中人为地将流速仪垂直了断面,如果再进行偏角修正,将造成流量偏小;③该站冬季测流时,若使用悬杆测流则不需要进行偏角修正,若采用铅鱼悬吊测流则应该测量流向偏角并对流速进行偏角修正。     

ADCP在天然河流大尺度紊动结构研究中的应用

介绍了声学多普勒流速剖面仪(ADCP)在天然河流大尺度紊动结构研究中的应用情况与ADCP的工作原理，并基于符合准恒定、准平衡条件的水流状况，根据大量的实测数据，对天然水流紊动特性进行了分析，加深了对天然水流紊动特性的认识．     

ADCP在长江内河流量比测试验与精度研究

根据长江中下游主要控制河段采用ADCP测流方式，结合长江河流水沙特性、测站特征和水文测船等具体情况，通过野外比测试验，针对ADCP存在的“适宜性”和流量测验精度等问题，进行了较为全面、深入、细致的分析研究．提出了一套能使ADCP适应于长江内河河流特性、现有测船条件的流量测验方法、精度指标等成果，具有广泛的推广应用价值。     

ADCP应用于泥沙测验探索

利用声学原理进行悬浮泥沙浓度的测验方法是声学界的重要课题，国外也曾用ADCP对泥沙进行观测研究。为配合航道建设工作的基础研究，长江委水文局长江口水文水资源勘测局尝试进行了ADCP泥沙观测研究的比测试验。分析了比测方法、资料处理方法，通过分析，得出利用ADCP所测分层回声强度来推求水体中泥沙含量在技术上是具有一定的可行性。     

ADCP与流速仪在洋山港的比测分析

声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,缩写ADCP)是1982年国际上发展的一种新的流速测量仪器.该仪器利用声学多普勒原理测量水流速度剖面,具有测验时间短、分辨率高、精度好、资料完整、信息量大的特点,特别适合于流态复杂条件下的测验,与传统的流速仪相比具有更高的测验效率.根据声学多普勒流速剖面仪(ADCP)和传统流速仪在洋山港大量比测测验资料,用数理统计方法和公式,对各项比测误差与精度进行统计与分析.分析结果表明,ADCP测验速度快、精度高,具有常规流速仪不可比拟的优越性.     

走航式ADCP技术在水文测验中的应用探讨

虽然走航式ADCP河流流量测验得到越来越广泛的应用,但因其受含沙量、河床流沙和船体等影响较大,使ADCP在一些条件下的使用受到制约。通过ADCP在高要水文站外接罗经、GPS的比测试验成果分析,探讨高洪期间ADCP测流技术的应用情况,解决ADCP在洪水期测流遇到的技术问题。