Quantitative relationship between surface sedimentary diatoms and water depth in North-Central Bohai Bay,China

To study the quantitative relationship between surface sedimentary diatoms and water depth,67 surface samples were collected for diatom analysis on eight profiles with water depth variation from the muddy intertidal zone to the shallow sea area in North-Central Bohai Bay,China.The results showed that the distribution of diatoms changed significantly in response to the change in water depth.Furthermore,the quantitative relationship between the distribution of dominant diatom species,their assemblages,and the water depth was established.The water depth optima for seven dominant species such as Cyclotella striata/stylorum,Paralia sulcata,and Coscinodiscus perforatus and the water depth indication range of seven diatom assemblages were obtained in the study area above the water depth(elevation)of-10 m.The quantitative relationship between surface sedimentary diatoms and water depth provides a proxy index for diatom-paleo-water depth reconstruction in the strata in Bohai Bay,China.

Online dynamic measurement of saturation-capillary pressure relation in sandy medium under water level fluctuation

An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.

Relationship between adjustment of low water level and utilization of water depth in Shashi Reach in middle Yangtze River

Hydrological,sediment,and bathymetric data of the Shashi Reach in the middle Yangtze River for the period of 1975-2018 were collected,and the characteristics of low water level changes and their impacts on utilization of water depth for navigation were investigated.The results showed that,during the study period,the Shashi Reach riverbed was significantly scoured and incised,with cross-sectional profiles showing overall narrowing and deepening.This indicated a strong potential to improve the water depth of the channel.The analysis of the temporal variation of in-channel topographical features showed that the Taipingkou diara underwent siltation and erosion,with its head gradually scoured and relocated downstream after 2008,and the Sanbatan diara continued to shrink and migrate leftwards.Low water levels with the same flow rate over the study period decreased.For instance,from 2003 to 2020,the water level at the Shashi hydrological station decreased to 1.37 m with a flow rate of 6000 m^(3)/s.Furthermore,the designed minimum navigable water level of the Shashi Reach was approximately 2.11m lower than the recommended level.In terms of utilization of the channel water depth,continuous scouring of the river channel is expected to result in a reduction in discharge at the Taipingkou mouth,which will improve the water depth conditions of the channel during the dry season in the Shashi Reach.With several channel regulation projects,the 3.5-m depth of the Shashi Reach would basically be unobstructed.This promotes utilization of the shipping route from the Taipingkou south branch to the Sanbatan north branch as the main navigation channel during the dry season.Considering the factors of current water depth and the clear width limitation of the navigation hole at the Jingzhou Yangtze River Bridge,this route can still be favored as the main navigation channel with a 4.5-m depth during the dry season.

Image-based Water Level Measurement Method under Stained Ruler

This paper propoes the water level measuring method based on the image, while the ruler used to indicate the water level is stained. The contamination of the ruler weakens or eliminates many features which are required for the image processing. However, the feature of the color difference between the ruler and the water surface are firmer on the environmental change compare to the other features. As the color differeaces are embossed, only the region of the ruler is limited to eliminate the noise, and the average image is produced by using several continuous frames. A histogram is then produced on the height axis of the produced intensity average image. Local peaks and local valleys are detected, and the section between the peak and valley which have the greatest change is looked for. The valley point at this very moment is used to detect the water level. The detected water level is then converted to the actual water level by using the mapping table. The proposed method is compared to the ultrasonic based method to evaluate its accuracy and efficiency on the various contaminated environments.

Determination of gross α and β activities in Zouma River based on online HPGe gamma measurement system

This paper describes a low-cost and fast method to evaluate gross α and β^(-) radioactivities in natural water based on an online high-purity germanium detector gamma measurement system.The major gamma activities in natural water are provided by natural and artificial radionuclides such as ^(40) K,^(137)Cs,and radionuclides belonging to ^(238)U and ^(232)Th series.The main a emitters related to gamma emissions in natural water are ^(224)Ra(240.98 keV)and ^(226)Ra(186.21 keV),and the β^(-) emitters are ^(40) K(1460.85 keV),^(214)Bi(609.31 keV),^(208)Tl(583.19 keV),and ^(214)Pb(351.93 keV).The formula for gross α and β^(-) activity concentration is based on these radionuclides,and the short half-life decay products are considered in the calculation.The detection efficiency of the device across energy region(0–3 MeV)is obtained through Monte Carlo simulation,and a calibration experiment is conducted to verify the simulation results.Gamma radioactivity is measured continuously for 114 d in Pixian County and Dongfeng Canal located in the Zouma River,Chengdu,Sichuan Province,China.A comparison of the calculation results and monitoring data from the Sichuan Management and Monitoring Center Station of Radioactive Environment indicates that the percentage and absolute error of a activity concentration is lower than 53%and 0.02 Bq/L,respectively,and that of β-activity concentration is lower than 33.2%and 0.016 Bq/L,respectively.The method can rapidly determine gross α and β^(-) activity concentrations in natural water online.

Numerical Simulation of the Binchuan Airgun Source Affected by Water Body

The numerical simulation of the influence of a reservoir water body on the Binchuan airgun source could provide a theoretical basis to analyze the data obtained from the active source detection and inversion of regional interior medium structures.Based on a medium model containing limited water body,we use the finite different method to simulate the effect of the water level,excitation energy and focal depth.The results show that the influence on the waveform amplitude caused by the water level changing is very large near the water body,and that a high water level or large amplitude change can have a larger effect.However,for stations beyond a certain epicentral distance,the influence will be weakened and kept stable.As for the Binchuan airgun source,amplitude fluctuation caused by the water level changing becomes very small(±0.05 times)after propagating a certain distance,so we can remove the influence of the water level changing by referring to the numerical simulation result.Wave amplitude increases linearly with the excitation energy and focal depth,therefore,the greater the energy and the deeper the focal depth,the better the effect of the excitation,and is more conducive in detecting remote and deep penetration underground structures.

江苏省平原水网区河湖生态水位确定探索与实践

保障河湖生态流量,事关江河湖泊健康。本文在分析江苏平原水网区域特点的基础上,选择生态水位作为河湖生态流量的表征指标,根据水利部确定的江苏省26条全国生态流量保障重点河湖名录,科学选定控制断面,采用1990—2020年水文序列资料,选用Qp法分析计算90%、95%、99%保证率下的水位,同步对比分析近10年最枯月水位、最低通航保证水位,最终确定了26条河湖的生态水位。通过制定保障措施方案、开展监测预警评估、强化统一调度管理等措施,全面保障区域河湖生态水位,为平原水网地区河湖生态水位的确定与保障提供了经验。

扬州城市规划区地下水应急供水方案可行性研究

突发事件会引起大范围的地表水污染,对城市供水水源的安全形成挑战,严重威胁人民生命安全,危害生态环境和经济社会稳定。地下水与地表环境联系较弱,利用地下水作为应急水源是最安全的水资源保障措施。本研究以扬州城市规划区为例,确定了规划区应急需水量为17.2万m^(3)/d,应急时长为15d,主要开采的第Ⅱ、Ⅲ承压含水层限采红线水位埋深分别为20m、30m,根据研究区应急供水需求制定了4种应急供水方案。方案1和2为水源地集中供水,方案3为分散式供水,方案4为分散与集中式联合供水。依据工作区水文地质条件和地下水位监测数据,基于HydroGeoSphere构建并校正了研究区三维地下水-地表水耦合数值模型,利用数值模型分析了不同供水方案应急抽水引起的地下水位降落趋势及其与地下水开采红线的关系。研究表明,分散与集中式联合供水方案可以明显减小工作区内的水位波动,减缓水源地的供水压力,降低地面沉降风险,对现有管网的利用也较为充分,可作为应急供水的首选方案。

雅鲁藏布江大拐弯地区河流水位日变化时空分异特征

径流(或水位)日变化是反映河流水文情势的重要方面,解析径流(水位)日变化特征有助于明晰河流水文动态过程和规律,揭示径流来源和产汇流机制。以藏东南雅鲁藏布江大拐弯地区的易贡藏布、帕隆藏布、曲宗藏布、拉月曲、金珠曲和白马西路河为对象,基于典型河段2022—2023年小时分辨率实测水位数据,采用数理统计和表征参数分析河流水位日变化时空分异特征,并结合降雨、冰川/积雪数据探究河流水位日变化影响因素。结果表明:研究区河流水位日变幅在汛期多高于非汛期,日水位数据分布在汛期多呈正偏(均值大于中值),汛后多呈负偏(均值小于中值);除白马西路河外,各河段水位日涨落过程在非汛期相对于汛期有所延迟,且汛后延迟趋势更明显;汛期各河段日水位上涨历时均小于回落历时,非汛期则多相反(拉月曲和金珠曲除外);白马西路河水位日变化主要受降雨过程扰动,而其他河流水位日变化主要受冰雪消融过程影响。

宿迁市河流生态水位管控目标与预警机制分析

针对宿迁市近年水环境保护与水生态修复实践,阐述了宿迁市开展的第一批及相关重要河道生态水位制定情况与实施政策,分析了河道生态水位管理的工程调度原则与预警机制方案设计等技术内容,提出了河道生态水位管控目标保障措施。相关技术方法对构建完善的生态水位目标管控长效机制,提升宿迁市河湖水生态环境质量具有重要决策参考价值。

根-土复合体岸坡渗流及稳定数值模拟

植物护岸中根系力学效应可显著提高岸坡浅层稳定性,但对降雨和水位变化等条件下,根系水力效应与力学效应之间相对关系变化对岸坡浅层稳定性影响的研究较少。采用数值分析方法模拟了岸坡根-土复合体从非饱和到饱和(降雨工况和水位上升工况)、从饱和到非饱和(水位下降工况)过程中根-土复合体水力效应对岸坡渗流场的影响,进一步分析了不同水力特性条件下根-土复合体对岸坡浅层稳定性的影响。模拟计算结果表明:(1)在设定的3种降雨强度下,根-土复合体的优先流入渗作用与降雨强度和降雨时间均呈正相关,而排水作用与降雨强度和降雨时间均呈负相关。在长历时的小降雨或短历时的强降雨情况下,由于降雨影响深度增大,根-土复合体水力效应带来的消极影响占主导地位。(2)在水位下降工况下,根-土复合体排水作用有滞后性,力学效应仍占主导地位;在水位上升工况下,根-土复合体增渗作用随水位上升速率增加而增强,根-土复合体的力学效应逐渐被水力效应所掩盖。研究结果对植物护岸工程应用具有借鉴意义,即使采用植物生态护岸,也应加强坡面排水和坡体排水措施。

基于单目视觉的无水尺水位测量方法

水位是水文监测的关键要素,其精准测量对洪涝灾害防御和水量计量具有重要的意义。随着智慧水利建设和视频设备的大规模部署,基于图像处理的水位识别方法发展迅速,是目前水利量测领域的前沿方向。本文提出了一种基于单目视觉的无水尺水位测量方法。该方法采用深度学习构建水面分割模型,自动从水岸图像中提取水位线;再根据相机标定得到的空间映射关系,结合断面约束,计算水位线像素坐标对应的三维空间坐标,进而处理得到水位值。该方法应用于室内河工模型水槽实验,水面分割准确,水位线平均错误分割像素个数为0.825,计算水位值的平均绝对误差约为1.5 mm,均方根误差约为1.9 mm。实验结果表明该方法准确测量了水位的变化过程。

基于双线激光测量系统的滚波成熟断面特征分析

为深入研究坡面薄层水流的滚波特性,该研究对坡面薄层水流深度测量系统的精度进行标定,并将其优化为双线激光水深测量系统,在3种坡度和6种流量条件下,采用非接触式测量方法实时测量滚波成熟断面位置的水深。结果表明:坡面薄层水流深度测量系统的精度确认为0.473 mm/格,双线激光水深测量系统的最佳间距为0.04 m。流量和坡度显著影响滚波波速、波高、波高差值及频率,流量的影响(效应量0.655~0.963)大于坡度(效应量0.232~0.874)。坡度显著影响波长,而流量对波长无显著影响。波速随流量增加而增加,但随坡度增加,流量对波速的影响降低。在不同坡度条件下,波高对流量的响应各异。3°坡度下,波高随流量增加先增高后降低,而在较大坡度下(9°和15°),波高处于小流量条件下(2~8 L/min)增幅较大,分别为3.74和4.63 mm。随着流量增大,3°与9°的波高差异增加,但9°与15°之间的差异则减小。此外,波高差值随流量增加显著增大,但随坡度的变化受到流量的影响差异呈现出先增大再减小的趋势。流量增加会导致频率增加,且15°坡度下增幅最大,为2.37 Hz。各坡度的频率差异随流量增大表现为先减小后增加,其临界流量值为8 L/min。小坡度下(3°)波长随流量波动增加,而在大坡度下(15°),较大流量会抑制波长发展。大流量条件下(16~20 L/min),各坡度的波长差异显著。该研究为提高坡面薄层水流测量精度,进一步探明薄层水流滚波的动力学特性提供理论依据。

基于北斗/GNSS-R的厘米级水位测量

水位变化监测是防洪抗旱的重点工作之一,全球导航卫星系统反射测量(Global Navigation Satellite System-Reflectome‐try,GNSS-R)技术已被证明可进行高精度、全天候、全天时的水位变化监测。我国北斗卫星导航系统(Beidou Navigation Satellite System,BDS)拥有丰富的频段数据,在GNSS-R遥感应用领域中具有广阔的应用前景。基于湖南省浏阳河流域建设的GNSS-R实验观测站数据,进一步研究了BDS在水位反演中的性能,分别采用频谱分析法和非线性拟合法对站点水位变化进行测量,并将实验结果与附近水文站的实测数据进行对比分析。结果表明,非线性拟合法相较于频谱分析法,水位测量精度大幅提升,均方根误差(RMSE)平均降低了66%,且多频数据融合后RMSE达到了1.8 cm,整体上BDS的水位反演性能与GPS相当。

天山北坡前山带蒙古沙棘不同集水造林技术的效果评价

【目的】探讨天山北坡前山带蒙古沙棘(Hippophae rhamnoides subsp.mongolica)不同集水造林技术对土壤含水率、造林成活率和保存率及株高的影响,结合造林成本进行效果评价,筛选出最佳的蒙古沙棘造林技术,为该地区的人工造林提供技术参考。【方法】以蒙古沙棘优良品种‘新棘1号’(H.rhamnoides‘xinji1’)为研究对象,通过双因素试验设计,设4个水平沟深度:H0(0 cm)、H1(20 cm)、H2(40 cm)、H3(60 cm)和4个保水措施:W0(裸地)、W1(膨润土)、W2(防草布)、W3(膨润土+防草布)。【结果】水平沟深度、保水措施及二者的交互作用均对土壤含水率、造林成活率和保存率及株高有显著影响;在同一保水措施下,随着水平沟深度增加,各指标越优,但造林成本随之增加;在同一水平沟深度下,整体以W3处理最佳,但造林成本也最高;结合造林成本,通过隶属函数评价法综合评价各集水造林技术的效果,H2W3处理得分最高,H0W0得分最低。【结论】本研究筛选出最佳的蒙古沙棘的造林技术为H2W3(40 cm深度+膨润土+覆防草布)处理。

基于GNSS双天线测姿的水位监测方法

水位监测是雨水情监测预报“第三道防线”中的重要内容,精确、实时的水位监测在洪涝灾害防御中至关重要。水位计是最常见的水位测量工具,其能有效测量特定区域的相对水位信息,但往往存在成本较高、空间分辨率较低等问题。由于全球导航卫星系统反射测量(Global Navigation Satellite System-Reflectometry,GNSS-R)技术具有低成本、高时空分辨率的优势,因此提出了一种基于全球导航卫星系统(Global Navigation Satellite System,GNSS)双天线测姿的实时水位监测新方法。该方法通过双差观测组合,消除了卫星钟差、接收机钟差、电离层延迟、对流层延迟等误差。为了验证该方法的稳定性和可靠性,在北京市东沙河站开展现场试验。2023年6月5日至7月10日的实验结果表明该方法可以实现1 Hz的水位监测,与现场水尺数据相比,均方根误差为2.88 cm。

基于改进YOLOX的城市河道智能水位测量算法

针对目前基于深度学习水位测量算法存在特征信息提取不充分问题,提出一种基于改进YOLOX的城市河道水位智能测量算法。为了提高YOLOX对多类别密集目标的识别率,在特征融合网络中引入CBAM注意力机制,并采用基于计算目标框信息的损失函数D-IoU加快模型收敛。该算法利用改进后的YOLOX对水尺刻度进行识别与统计,并计算出水位值。试验表明提出的新算法对水尺刻度和数字的平均识别率分别达98.62%和92.23%,最终计算水位的平均误差为1.16 cm,较其他图像识别水位测量算法的平均误差减少了1.76 cm,可实现高精度智能测量城市河道的水位值。

枞阳闸水文站雷达水位计与人工观测水位比测研究

本文以枞阳闸水文站为研究对象,为验证雷达水位计在测站水位监测中的精度性,选取2023年4-6月雷达水位计观测水位数据,结合人工观测方式实现同步分析。结果表明,基于《水位观测标准》要求,枞阳闸水文站雷达水位计与人工水位观测比测误差符合指标要求,雷达观测资料可供该测站水文资料正式使用。

基于同位素的神东矿区植物吸水深度及生态水位研究

为了研究神东矿区煤炭开采造成的地下水位下降是否会对地表植被的生存产生威胁,以神东矿区分布最广泛的植物沙蒿为研究对象,采用水稳定同位素示踪技术研究神东矿区成年沙蒿的根系吸水深度,通过MixSIAR同位素混合模型分析成年沙蒿的土壤水分吸收策略。结果显示,研究区成年沙蒿的吸水的极限深度为2.5~3 m,沙蒿会较均匀的吸收不同深度的土壤水分,但其水分利用策略也会受到土壤含水率高低的影响。该研究揭示了研究区成年沙蒿的根系吸水深度和水分利用策略,从植物角度说明了该区域生态水位的下限是2.5~3 m。

海洋测绘水深测量成果质量控制

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