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1.
OBS浊度标定与悬沙浓度误差分析 总被引：2，自引：0，他引：2
利用光学后向散射浊度计OBS-3A,在长江河口南槽进行大小潮周期连续观测。利用OBS室内和现场浊度标定,计算不同潮时OBS观测悬沙浓度相对误差,并对影响其观测精度因素进行分析。主要结果有:(1)现场OBS标定R值比室内标定偏低,但也在0.8以上;(2)大潮平均相对误差值变化比小潮大,在悬沙浓度低于1.5kg/m3条件下,大小潮悬沙浓度平均相对误差都在15%以下;(3)悬沙粒径大小是影响OBS观测精度的主要因素,生物、泥沙颜色、水色和水中气泡等因素也对观测结果产生一定影响。 相似文献
2.
江苏王港盐沼潮沟的水动力和悬沙输运过程 总被引：4，自引：2，他引：4
在江苏王港盐沼湿地的两条潮沟内分别设立观测站位，进行了水位、潮流流速和悬沙浓度的观测。结果表明，潮沟水流的流速与潮位变化率之问存在着显著的线性相关关系，并受到潮沟本身特征(如潮沟级别、坡度、所在部位等)的影响。潮周期中的流速突变现象发生于涨潮初期、潮沟满溢和滩面水归槽阶段。涨潮期间，悬沙浓度和流速有显著的正相关关系，悬沙浓度的变化受再悬浮作用控制；落潮期间，悬沙浓度的变化基本上与流速大小无关，悬沙输运以平流作用为主。大潮期间盐沼潮沟内悬沙净输运方向由陆向海。 相似文献
3.
悬沙浓度是淤泥质海岸重要的环境指标。为探讨潮滩悬沙浓度和悬沙输运对风暴事件的响应过程及其动力机制,于2014年9月"凤凰"台风过境前、中、后在长江三角洲南汇潮滩进行了现场观测,获得同步高分辨率的水深、波高、近底流速和浊度剖面时间序列(9个潮周期)。结果表明,风暴中平均和最大波高、波-流联合底床剪切应力、悬沙浓度和悬沙输运率可比平静天气高数倍;风暴期间高潮位低流速阶段悬沙沉降导致近底发育数十厘米厚的浮泥层(悬沙浓度大于10 g/L)。研究认为风暴事件中淤泥质海岸悬沙浓度和悬沙输运的剧烈变化其根本动力机制是风暴把巨大能量传递给近岸水体,进而显著增大波-流联合底床剪切应力,导致细颗粒泥沙再悬浮。 相似文献
4.
《应用海洋学学报》2020,(2)
近底层悬沙时空变化对于理解河口冲淤变化有着至关重要的作用。然而,长期以来河口近底层水体悬沙浓度的连续变化大都是基于单点观测数据或水样处理获取。基于此,本研究利用光学仪器边界层悬浮物剖面测量仪(Argus Surface Meter Ⅳ,ASM-Ⅳ)获得长江口南槽近底层进行连续10 d的实测数据,探讨ASM-Ⅳ仪器监测悬沙浓度精度的有效性。结果表明:(1)传统仪器布设方法所获取的数据,相对误差高于基于ASM-Ⅳ所测误差,在大、中及小潮期间的平均误差值分别为24. 15%、17. 31%和16. 18%;越靠近底部河床,相对误差从距底52 cm向下随距底距离的减小而逐渐增大;(2)对于近底层单宽悬沙通量测量结果而言,传统测量仪器布设方法所测量数值一般偏小;(3)大潮时期近底层1 m内的水体悬沙分布均匀,分层不明显;在中、小潮时期,与近底层1 m内平均悬沙浓度相差最大的点皆位于距底20～50 cm附近。因而,近底层悬沙浓度测量时间在大潮时期或越靠近底层,利用ASM-Ⅳ监测近底层悬沙浓度值更为准确。中、小潮时期利用单点或采集水样测量时,选取0. 8H层水体悬沙浓度代替近底层悬沙浓度较最底部水体悬沙浓度更为准确。 相似文献
5.
近底层悬沙时空变化对于理解河口冲淤变化有着至关重要的作用。然而,长期以来河口近底层水体悬沙浓度的连续变化大都是基于单点观测数据或水样处理获取。基于此,本研究利用光学仪器边界层悬浮物剖面测量仪(Argus Surface Meter IV,ASM-IV)获得长江口南槽近底层进行连续10 d的实测数据,探讨ASM-IV仪器监测悬沙浓度精度的有效性。结果表明:(1)传统仪器布设方法所获取的数据,相对误差高于基于ASM-IV所测误差,在大、中及小潮期间的平均误差值分别为24.15%、17.31%和16.18%;越靠近底部河床,相对误差从距底52 cm向下随距底距离的减小而逐渐增大;(2)对于近底层单宽悬沙通量测量结果而言,传统测量仪器布设方法所测量数值一般偏小;(3)大潮时期近底层1 m内的水体悬沙分布均匀,分层不明显;在中、小潮时期,与近底层1 m内平均悬沙浓度相差最大的点皆位于距底20~50 cm附近。因而,近底层悬沙浓度测量时间在大潮时期或越靠近底层,利用ASM-IV监测近底层悬沙浓度值更为准确。中、小潮时期利用单点或采集水样测量时,选取0.8H层水体悬沙浓度代替近底层悬沙浓度较最底部水体悬沙浓度更为准确。 相似文献
6.
7.
江苏大丰潮滩潮流边界层特征研究 总被引：7，自引：0，他引：7
2003年7月中小潮期间使用MIDAS-400用户化数据采集系统在江苏大丰潮滩上进行了垂向多层位同步的流速和悬沙浓度观测。根据观测资料研究了潮流作用下的潮滩底部边界层过程,结果表明,观测地点的潮汐不对称现象十分明显,落潮流速、历时和输水输沙量皆明显大于涨潮;在潮周期内的多数时间里流速剖面符合对数分布,但在风力较强、水流快速增加和流速缓慢的情况下,流速剖面常偏离对数分布;悬沙颗粒垂向混合均匀,悬沙浓度剖面符合Rouse公式;落潮时的底部切应力和摩阻流速明显大于涨潮,摩阻流速与各水层流速通常有较好的线性关系;滩面糙度主要与沙纹形态和推移质运动强度有关,它与摩阻流速存在密切关系;悬沙浓度具有明显的减阻效应,受其影响,摩阻流速和底部切应力分别减小了28%~41%和40%~62%。 相似文献
8.
开展枯季河口悬沙输运机理研究对于揭示弱径流条件下的陆海相互作用、河口季节性冲淤和水沙关系等具有重要的科学意义.本文根据2018年12月18-25日长江口南槽3个站位连续13个潮周期的同步流速、流向和悬沙浓度等观测资料,运用通量机制分解法研究了各输沙项的特征、贡献和输运机理.结果 表明,从小潮至大潮流速和悬沙浓度不断增加,由南槽上部至下部流速和悬沙浓度逐渐降低.观测期间平均流速与平均悬沙浓度存在明显的正线性关系,但受底质空间差异影响,悬沙浓度对流速的响应强度存在显著的空间变化.枯季期间南槽存在着中上部向陆净输沙、下部向海净输沙的空间输运格局.平流输沙和潮泵输沙是影响和控制净输沙的关键因素,二者的强度和贡献存在明显的潮周期变化和空间变化,垂向环流输沙的强度很弱,对净输沙贡献很小.南槽涨落潮输沙不对称现象明显,流速、悬沙浓度和历时都具有一定的涨落潮不对称性,这些不对称现象共同调节和控制着潮周期净输沙强度和方向的时空变化. 相似文献
9.
浅海悬沙浓度观测方法的对比研究 总被引：4，自引：0，他引：4
在动力和沉积条件复杂的浅海海域获取水-体的悬沙浓度有多种方法,目前较先进的主要是声学和光学浊度测量方法,但均需通过现场采集水样进行浊度标定;水样的分析方法主要有抽滤法和沉淀干燥法。根据2010年3—4月在厦门九龙江口获取的光学(OBS、LISST-100X)和声学(ADCP、ADP和ADV)浊度数据,以及现场同步水样,对这两种获取悬沙浓度的方法进行了比较;2011年2—3月在长江口北支获取水样,分别使用抽滤法和沉淀干燥法获取悬沙浓度数据进行比对分析。结果表明,声学和光学方法都具有较高的精度,在同一观测层位,光学与声学仪器的相对误差均较小;由于声波在水体中传播距离较远,声学方法可获得沿水深的整个剖面的信息,因而比光学仪器具有更高的空间分辨率和测量范围。对比发现,抽滤法获得的悬沙浓度数值略低于沉淀干燥法获得的结果,可能与沉淀干燥法难以洗净盐分有关。 相似文献
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11.
Observations of boundary layer parameters and suspended sediment transport over the intertidal flats of northern Jiangsu, China 总被引：7，自引：0，他引：7
A current-turbidity monitoring system (CTMS) was deployed on the intertidal flat at Wanggang, northern Jiangsu during October 16-17, 2000, to measure the tidal current speeds and seawater turbidities at 5 levels above the seabed. Based upon the logarithmic-prof‘de equation, the boundary layer parameters, i.e., u*, Z0 and C60, were obtained for 247 tidal flow velocity prof‘des. Around 90% of the profiles were logarithmic according to the critical correlation coefficient. Internal consistency analysis shows that these parameters derived by different methods are consistent with each other. In addition, the height of the bedforms observed is close to the seabed roughness lengths calculated from the velocity prof‘des, indicating that the boundary layer parameters obtained can reveal the conditions at the sedimentwater interface on the intertidal flats. Suspended sediment concentrations were obtained from the 5 CTMS turbidity meters using laboratory and in-situ calibrations. The results show that the in-situ calibrated SSCs have a much higher accuracy than the laboratory calibrated ones. Calculation of suspended sediment fluxes on the intertidal flats, with a magnitude of 104 kg/m per spring tidal cycle, indicates that suspended sediment moves towards the northwest, which is reversal to the transport pattern controlled by the southward Northern Jiangsu Coastal Current in the sub-tidal zone and adjacent shallow waters. 相似文献
12.
基于ADP-XR和OBS-3A的潮滩水文泥沙过程研究 以胶州湾北部红岛潮滩为例 总被引：2，自引：1，他引：2
于2004年8月17~24日在胶州湾北部红岛潮滩上用OBS-3A和ADP-XR观测了水深、浊度、水平和垂直流速、回声强度、波浪、盐度、水温等水文泥沙要素,同时采集了悬沙和底沙样品作粒度分析.结果和结论为:(1)潮流动力较弱,表层和近底层最大流速分别只有31和26cm/s;(2)弱潮流动力导致潮周期大部分时间的悬沙浓度小于30mg/dm3,但浅水阶段近底悬沙浓度为100~1000mg/dm3;浅水阶段的短暂高悬浮泥沙浓度和其余长淹没时段的低悬沙浓度共同构成悬沙浓度的“U”形潮周期过程线;(3)悬沙浓度的垂直成层分布主要发生在潮周期的深水阶段和平静天气;(4)由于潮流弱和风浪的干扰,悬沙浓度未呈现大小潮周期的变化规律;(5)水体盐度为23.6~29.5;(6)淹没期的温度(21.4~28.6℃)比出露期的(19.3~30.9℃)稳定,温度极高值出现在午后出露期,而极低值出现在凌晨出露期;(7)“浅水效应”是弱动力潮滩泥沙运动的重要特点. 相似文献
13.
ADCP application for long-term monitoring of coastal water 总被引：2，自引：1，他引：2
Three kind of application of ADCP is reported for long-term monitoring in coastal sea. (1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed at MT (Marine Tower) Station of Kansai International Airport in the Osaka Bay, Japan. The correlation between the turbidity and echo intensity in the surface layer is not good because air bubbles generated by breaking wave are not detected by the turbidity meter, but detected well by ADCP. When estimating the turbidity consists ofplankrton population from echo intensity, the effect of bubbles have to be eliminated. (2) Monitoring stirring up of bottom sediment. The special observation was carried out by using following two ADCP in the Osaka Bay, One ADCP was installed upward on the sea. The other ADCP was hanged downward at the gate type stand about 3 m above from the bottom. At the spring tide, high echo intensities indicating the stirring up of bottom sediment were observed. (3) The monitoring for the boundary condition of water mixing at an estuary. In summer season, the ADCP was set at the mouth of Tanabe Bay in Wakayama Prefecture, Japan. During the observation, water temperature near the bottom showed remarkable falls with interval of about 5～7d. When the bottom temperature fell, the inflow current with low echo intensity water appears at the bottom layer in the ADCP record. It is concluded that when occasional weak northeast wind makes weak coastal upwelling at the mouth of the bay, the combination ofupwelling with internal tidal flow causes remarkable water exchange and dispels the red tide. 相似文献
14.
径流量和海平面变化对河口最大浑浊带的影响 总被引：2，自引：0，他引：2
应用改进的ECOM模式,耦合泥沙输运方程,研究径流量和海平面变化对河口最大浑浊带的影响.河口最大浑浊带位于滞流点处,底层上下游余流均向该处输运泥沙,造成该处泥沙汇合,而由流场辐合产生的上升流又使该处的泥沙不易落淤.由于盐水入侵带来的高盐水位于北岸的底层,其斜压效应使底层的横向环流由北向南流动,把底层高浓度的泥沙向南岸平流,使得最大浑浊带位于南岸.研究河口最大浑浊带现象必须使用三维泥沙输运模式.在径流量增大的情况下,与控制试验相比底层向陆的密度流减弱,滞流点下移,导致最大浑浊带也下移;因上游来沙量增加,在最大浑浊带中心和河口拦门沙处悬浮泥沙浓度趋于增加.在径流量减少的情况下,最大浑浊带的变化趋势与径流量增大情况的结果相反.在海平面上升的情况下,拦门沙区域底层向陆的密度流趋于增强,滞流点上移,最大浑浊带也相应向上游移动;最大浑浊带中心处泥沙浓度趋于增大,但口门拦门沙处泥沙浓度趋于减小.径流量和海平面变化对最大浑浊带影响明显. 相似文献
15.
Sedimentation process of fine-grained terrigenous red soils was observed on the seafloor by coral reefs near an estuary using a paired mooring of turbidity meter and sediment trap or a mooring of sediment trap and current meter. Silty clays contained in the bottom calcareous sands were mainly resuspended and trapped in both surface and bottom layer traps, at noncatastrophic normal sedimentation periods. In addition, silty clays were supplied to this mooring site by inflowing river. Turbidity and the flux rate determined by sediment traps show certain relationship accompanied with the coefficient, which is changed by precipitation, current, and other conditions. Resuspension process caused by a typhoon was recorded as both core sequence of sediment trap and time-series data of bottom current. Maximum velocity of 49.5 cm/s was recorded from bottom currents resulting from the passing of attyphoon at the mooring site. A graded sand layer is interbedded in dark-gray, silty clay and considered to be a resuspended sediment resulting from the passing of the typhoon. Flux of the resuspended sediments by the typhoon was estimated from this core sequence and compared to the flux observed at the normal sedimentation. 相似文献
16.
Tomoharu Senjyu Hidekazu Yasuda Shigehiko Sugihara Masato Kamizono 《Journal of Oceanography》2001,57(1):15-27
A hydrographic survey and a 25-hour stationary observation were carried out in the western part of Suo-Nada in the summer of 1998 to elucidate the formation mechanism of the oxygen-deficient water mass. A steep thermocline and halocline separated the upper layer water from the bottom water over the observational area except for near the Kanmon Strait. The bottom water, in comparison with the upper layer water, indicated lower temperature, higher salinity, lower dissolved oxygen, higher turbidity, and higher chlorophyll a. Turbidity in the upper layer water changed with semi-diurnal period while the bottom water turbidity showed a quarter-diurnal variation, though the M2 tidal current prevailed in both waters. From the turbidity distribution and the current variation, it is revealed that the turbidity in the upper layer water is controlled by the advection due to the M2 tidal current. On the other hand, the quarter-diurnal variation in the bottom water turbidity is caused by the resuspension of bottom sediments due to the M2 tidal current. The steep thermocline and halocline were maintained throughout the observation period in spite of the rather strong tidal currents. This implies an active intrusion of the low temperature and high salinity water from the east to the bottom of Suo-Nada. Based on the observational results, a hypothesis on the oxygen-deficient water mass formation was proposed; the periodical turbidity variation in the bottom water quickly modifies the oxygen-rich water in the east to the oxygen-deficient bottom water in Suo-Nada in a course of circulation. 相似文献
17.
The beam attenuation coefficient, organic carbon (POC) and organic nitrogen (PON) contents of suspended materials in Etauchi
Bay, which has little inflow of river water as well as very weak tidal current (maximum speed: 6.5cm·sec−1), were measured as a function of depth for all seasons to understand a seasonal variation of bottom turbidity layer. In spring
and summer, the beam attenuation coefficient in bottom layer and POC and PON contents of suspended materials in the surface
water layer increased with time, which brought the occurrence of the bottom turbidity layer. From autumn to winter, however,
their concentrations became low and constant over the whole depth almost independent of time. As a result, the bottom turbidity
layer disappeared in winter and beam attenuation coefficient became constant over the whole depth. From these results, it
may be considered that the bottom turbidity layer was produced by phytodetritus brought from surface water layer, rather than
by resuspension of bottom sediment in Etauchi Bay. 相似文献
18.
根据光学后散射传感器(Optical Backscatter Sensor,OBS)和声学后散射传感器(Acoustic Backscatting Sensor,ABS)估算悬浮沉积物质量浓度(Suspended sediment concentration,SSC)的原理,在水槽实验室不同波况产生较高悬浮沉积物质量浓度的条件下运用OBS仪器ASM-IV(激光边界层泥沙剖面仪)和ABS仪器AQUAscat1000(多频声学悬沙剖面仪)观测并记录数据。然后用水槽实验抽取的水样标定光学和声学仪器,反演得到高精度的垂向泥沙浓度分布剖面。结果表明,OBS仪器ASM-IV上的不同光学探头测得的浊度与SSC可以用同一个线性关系描述,相关系数高达0.996,进而能够高精度(垂向间距1cm)地反演垂向的SSC剖面;对于本组水槽实验的粉土底质和不同的波况而言,声学仪器比光学仪器的量测精度低;不同频率声学仪器换能器的量测值可相差几个数量级,不同波况条件下的声学仪器反演值与实测SSC的相关性系数在0.716~0.974变化。 相似文献
19.
河口最大浑浊带形成的动力模式和数值试验 总被引：8，自引：0，他引：8
应用改进的ECOM模式，耦合泥沙输运模型，研究理想河口最大浑浊带形成的动力机制。河口最大浑浊带位于滞流点处，上下游余流均向该处输运泥沙，造成该处泥沙汇合，而由流场辐合产生的上升流又使该处的泥沙不易落淤。南岸(河口东向)的泥沙浓度比北岸高，最大浑浊带位于南岸，这是由于盐水入侵带来的高盐水位于北岸的底层，其斜压效应使底层的环流由北向南流动，把底层高浓度的泥沙向南岸平流，聚集于南岸底层。除上游河流泥沙来源外，强大的涨落潮流冲刷床面，使沉降于床面的泥沙再次悬浮，成为余流输运泥沙的来源之一。 相似文献
20.
Vertical distributions of turbidity & phytodetritus (Chl.a and pheopigment), and their seasonal variations were measured in the deep water column of Sagami Bay, Japan, in June 1999, February 2000 and May 2000. Observations were carried out at eight stations along an east-west section of Sagami Bay using a CTD/water sampling system equipped with a memory-type infrared back-scattering meter which had been calibrated for the suspended particles collected in Sagami Bay. Turbidity increased close to the bottom in both summer and winter, indicating the existence of a benthic nepheloid layer throughout the year. But the vertical gradient of turbidity was much larger in summer than in winter. The concentration of Chl.a and pheopigment also increased in the benthic layer in summer, sometimes reaching values of more than 0.01 and 0.2 μg/l, respectively, much higher than those reported in hemipelagic regions of the ocean. In winter, on the other hand, Chl.a kept a constant low value throughout the deep water column. This indicates that the turbid water mass formed in the benthic layer in summer derives from the deposition of large amounts of phytodetritus in spring and the resuspension of these aggregates, which are subsequently decomposed in the benthic layer during the following autumn. Unlike the benthic boundary layer, the turbidity of intermediate water was lower in summer rather than in winter. Because the phytoplankton aggregates exported from the surface water during the spring bloom not only supply phytodetritus to the benthic layer but also scavenge the suspended particles in the water column, the steep vertical gradient of turbidity observed in summer may reflect the dynamic interaction between suspended and sinking particles in the deep water column. 相似文献