Study on the Lowest Navigable Water Level

The design lowest navigable water level is a primary index to the channel grade division.But differ- ent method can get different calculated result,and that even brings contradiction to decide the navigation grade.In this paper the differences between guaranteed rate method and guaranteed rate-frequency method on the fundamental concept of guaranteed rate and the calculated result are carried out.According to the theoreti- cal expression forms of the two methods,the reason leading to the difference is an...

桃源枢纽河段通航水流条件数值模拟

针对桃源枢纽船闸存在的碍航问题,以沅水桃源枢纽二线船闸建设工程为项目依托,采用二维动力学数值模拟方法对桃源枢纽—周文庙水文站河段通航水流条件进行研究。基于对多工况水深、水位、流速等参数的分析,进而研究枢纽与坝下航道的通航水流条件和碍航滩段,并根据滩险问题提出挖槽疏浚等航道整治措施。结果表明:在现有地形条件下工况1(Q=217 m^(3)/s)和工况2(Q=380 m^(3)/s)在距桃源枢纽0~20 km河段和80~95 km河段碍航问题突出,当流量大于工况3(1 233 m^(3)/s)时满足Ⅲ级航道尺度要求。经数学模型验证,对碍航滩段进行拟定的挖槽疏浚等措施能够有效改善航道的通航水流条件。

平原河网地区内河通航水域认定原则及通航标准研究

针对内河通航水域认定工作中存在的管理边界模糊、认定原则不一、通航标准空白等问题,结合平原河网地区地域及水域特点,通过梳理法律法规、技术标准、各地已发布的通航水域管理文件,以满足使用需求和保护通航资源为原则,提出将航道、现状有运营码头的河道、现状有货船通航的河道、地理区位重要且对现有航道网络能起到补充支持的河道、拟开发水上游览经营活动的水域、目前无通航需求但仍具备一定通航能力的河道等6类水域认定为通航水域;现状通航条件较差且无规划使用需求的水域以及城市园林水域不宜认定为通航水域。另外,本着适度合理的原则,提出河道、湖泊等通航水域上的通航标准。研究成果可为通航水域管理工作提供理论支撑和技术参考。

柳江Ⅱ级航道工程可行性研究

柳江Ⅱ级航道作为西南水运出海北线通道的重要组成部分,但运力不足。根据整治河段自然资源分布、社会经济发展与工业布局现状及规划、航运发展前景对建设柳江Ⅱ级航道进行可行性研究。建立柳江Ⅱ级航道设计标准和设计原则,依据通航率和航道等级,提出一种计算航道尺寸的方法,并基于柳江Ⅱ级航道工程设计最低通航水位和河段分期水位-流量计算柳江Ⅱ级航道流量,根据Ⅱ级航道弯曲半径的要求及使用和维护的便利性,提出滩段航道线路方案,实现全长173 km的2 000吨级Ⅱ级航道建设,根据运量预测2025、2035、2050年货运量分别为2 670万、4 810万、6 500万t。

Meteorological applications of precipitable water vapor measurements retrieved by the national GNSS network of China

In this study, the Global Navigation Satellite System （GNSS） network of China is discussed, which can be used to monitor atmospheric precipitable water vapor （PWV）. By the end of 2013, the network had 952 GNSS sites, including 260 belonging to the Crustal Movement Observation Network of China （CMONOC） and 692 belonging to the China Meteorological Administration GNSS network （CMAGN）. Additionally, GNSS observation collecting and data processing procedures are presented and PWV data quality control methods are investigated. PWV levels as determined by GNSS and radiosonde are compared. The results show that GNSS estimates are generally in good agreement with measurements of radio- sondes and water vapor radiometers （WVR）. The PWV retrieved by the national GNSS network is used in weather forecasting, assimilation of data into numerical weather prediction models, the validation of PWV estimates by radiosonde, and plum rain monitoring. The network is also used to monitor the total ionospheric electron content.

Evaluation of surface temperature and pressure derived from MERRA-2 and ERA5 reanalysis datasets and their applications in hourly GNSS precipitable water vapor retrieval over China

Temperature and pressure play key roles in Global Navigation Satellite System(GNSS) precipitable water vapor(PWV) retrieval. The National Aeronautics and Space Administration(NASA) and European Center for Medium-Range Weather Forecasts(ECMWF) have released their latest reanalysis product: the modern-era retrospective analysis for research and applications, version 2(MERRA-2) and the fifthgeneration ECMWF reanalysis(ERA5), respectively. Based on the reanalysis data, we evaluate and analyze the accuracy of the surface temperature and pressure products in China using the the measured temperature and pressure data from 609 ground meteorological stations in 2017 as reference values.Then the accuracy of the two datasets and their performances in estimating GNSS PWV are analyzed. The PWV derived from the pressure and temperature products of ERA5 and MERRA-2 has high accuracy. The annual average biases of pressure and temperature for ERA5 are-0.07 hPa and 0.45 K, with the root mean square error(RMSE) of 0.95 hPa and 2.04 K, respectively. The annual average biases of pressure and temperature for MERRA-2 are-0.01 hPa and 0.38 K, with the RMSE of 1.08 h Pa and 2.66 K, respectively.The accuracy of ERA5 is slightly higher than that of MERRA-2. The two reanalysis data show negative biases in most regions of China, with the highest to lowest accuracy in the following order: the south,north, northwest, and Tibet Plateau. Comparing the GNSS PWV calculated using MERRA-2(GNSS MERRA-2 PWV) and ERA5(GNSS ERA5 PWV) with the radiosonde-derived PWV from 48 co-located GNSS stations and the measured PWV of the co-location radiosonde stations, it is found that the accuracy of GNSS ERA5 PWV is better than that of GNSS MERRA-2 PWV. These results show the different applicability of surface temperature and pressure products from MERRA-2 and ERA5 data, indicating that both have important applications in meteorological research and GNSS water vapor monitoring in China.

Spatial variation of precipitable water vapor derived from GNSS CORS in Thailand

This research aims to study a distance variation of Precipitable Water Vapor(PWV) between Continuously Operating Reference Stations(CORS) in Thailand using a Precise Point Positioning(PPP) technique.Nowadays, Global Navigation Satellite System(GNSS) CORS is not only used to obtain precise positioning applications but also plays an important role in meteorological applications. With a recent establishment of GNSS CORS around Thai region, the PWV can be accurately derived from these GNSS CORS data using the scientific Position and Navigation Data Analyst(PANDA) GNSS processing software. One-year period of GNSS CORS data collected between January 1 and December 31, 2016 are used in this study. The GNSS CORS data used in this study are gathered from various agencies, i.e. Chulalongkorn University,Department of Lands and Department of Public Works and Town & Country Planning. However, a coverage distance from each GNSS CORS for PWV estimations is not precisely determined for Thai region.This information can help reduce expenses in an installation and maintenance of meteorology sensors at each GNSS CORS. Therefore, this paper focuses on determining the distance variation of PWV between GNSS CORS and the coverage distance from each CORS for PWV estimations. The result shows that the coverage distance from each CORS at 74 km or less can provide accurate PWV in Thai region.

Water Resources, Infrastructure Restoration, and Protection of the Upper Mississippi River Basin

The Upper Mississippi River flows approximately 2000 km from Lake Itasca, Minnesota to Cairo, Illinois where it is confluences with the Ohio River to form the Lower Mississippi River. North of the confluence, numerous snags, sand bars, rapids, and other obstructions made the Upper Mississippi River travel difficult. This paper highlights how the geological and landscape resources of the Upper Mississippi River and tributary watershed were responsible for the successful economic development of this historically rich region of North America. Environmental challenges include an attempt to keep invasive species such as the Asian carp out of the rivers and lakes north of the Twin Cities. In an attempt to protect the Mississippi River resource, Environmental and Conservation groups have opposed continued navigation through Minneapolis and St. Paul and the planned Upper Mississippi River navigation infrastructure restoration by the United States Corps of Engineers including the upper and lower St. Anthony locks and dams. These Environmental, Conservation and Save the River groups are attempting to mitigate the historic highest and best use of the Mississippi River and adjacent watershed, navigation, and economic development, by having the urban river restored to the natural state.

Diurnal variation of precipitable water vapor over Central and South America

Annual and seasonal diurnal precipitable water vapor(PWV)variations over Central and South America are analyzed for the period 2007-2013.PWV values were obtained from Global Navigation Satellite Systems(GNSS)observations of sixty-nine GNSS tracking stations.Histograms by climate categories show that PWV values for temperate,polar and cold dry climate have a positive skewed distribution and for tropical climates(except for monsoon subtype)show a negative skewed distribution.The diurnal PWV and surface temperatures(T)anomaly datasets are analyzed by using principal components analysis(PCA).The first two modes represent more than 90%of the PWV variability.The first PCA mode of PWV variability shows a maximum amplitude value in the late afternoon few hours later than the respective values for surface temperature(T),therefore the temperature and the surface conditions(to yield evaporation)could be the main agents producing this variability;PWV variability in inland stations are mainly represented by this mode.The second mode of PWV variability shows a maximum amplitude at midnight,a possible explanation of this behavior is the effect of the sea/valley breeze.The coastal and valley stations are affected by this mode in most cases.Finally,the"undefined"stations,surrounded by several water bodies,are mainly affected by the second mode with negative eigenvectors.In the seasonal analysis,both the undefined and valley stations constitute the main cases that show a sea or valley breeze only during some seasons,while the rest of the year they present a behavior according to their temperature and the surface conditions.As a result,the PCA proves to be a useful numerical tool to represent the main sub-daily PWV variabilities.

根据DS理论的船舶风险因素评估分析

针对船舶航行风险评估中存在许多不确定影响因素的问题,提出了在模糊风险评估证据理论基础上建立的风险评估方法。在证据集理论空间中,每一事件均可确认为模糊集合子集且融入了模糊概率理论,从而更全面地描述行业学者的专业经验或证据诠释,由此得出了模糊证据理论质量函数的描述法。最后应用其船舶安全系统,提出了船舶风险因素识别和风险评估详细程序。计算结果证明,此方法可有效避免决策失误,且简单、易行,有较强的推广和应用价值。

中国区域ERA5-ZTD/PWV精度评估与台风事件响应研究

再分析数据能够提供多种历史气象数据同化产品,为了评估欧洲中期天气预报中心的最新一代ERA5再分析数据集估计的天顶对流层延迟(Zenith Tropospheric Delay,ZTD)和大气可降水量(Precipitable Water Vapor,PWV)产品在中国区域的精度,利用2017—2019年中国区域内14个全球导航卫星系统地面监测站和89个探空站反演的ZTD和PWV数据分别对ERA5-ZTD和ERA5-PWV精度进行了评估。结果表明,除青藏地区的站点外,ERA5-ZTD的精度分布较为均匀,平均Bias、RMSE和STD分别为-6.3 mm、19.3 mm和17.5 mm;ERA5-PWV的精度分布呈现西部内陆高和东南沿海低的趋势,平均Bias、RMSE和STD分别为0.3 mm,2.9 mm和2.7 mm。此外,在研究2019年“利奇马”台风期间ZTD和PWV的时空分布中,提出了使用水汽到达时间差的方法定量估计台风的水汽移动速度。得到台风期间ZTD和PWV具有相同的空间分布规律,且移动方向与台风的移动路径方向是一致的,估计的水汽平均移动速度为12.4 km/h,与台风的平均移动速度16.1 km/h非常接近。因此,ERA5-ZTD/PWV在中国区域内具有较高的精度,ZTD和PWV可作为重要气象因子为台风的预警预报研究提供重要参考。

长江上游水井湾航道整治数值模拟

水井湾滩段是长江上游弯道分汊河道,具有急、浅、险等多种碍航特性。洪中枯流量的差异引起主支汊分流比与分沙比的变化,河床不稳定。采用数值模拟方法,结合丁顺坝平面初步布置方案,研究丁顺坝坝头不同偏角布置下水井湾航道的通航水流条件及汊道分流比变化规律,对比分析各布置方案的计算结果得到平面布置最优方案。研究表明:通航水流条件与丁顺坝坝头偏角不成正向变动关系,坝头偏角存在合适区间;分汊主河道分流比与流量成反向变动关系,坝头偏角对河道分流比影响较小。研究结果可为同类型河流航道整治方案提供理论依据。

引江补汉工程丹江口下游近坝段枯水期通航水位恢复试验研究

引江补汉工程补水口位于丹江口大坝下游安乐河出口约5 km处,且补水量与调水量基本一致,工程对航道的影响主要体现在减水段,为恢复枯水期通航水位需要开展航道综合治理。利用河工模型试验论证了综合治理方案的效果,并对方案进行了优化及进一步论证。结果表明,减水-补水212 m 3/s方案尾门水位分别为86.47、85.90 m条件下,引航道口—黄家港段水位下降,黄家港以下水位保持不变,其中引航道口水位下降幅度最大,分别下降0.08、0.19 m;综合治理方案1实施后引航道口水位下降均为0.02 m,减水段的水位仍未恢复至调水前的水平,主因是从安乐河口补水的水流并未能进入到左侧主航道内;基于试验研究结果,建议对综合治理方案进行优化,在沧浪洲出水口下沿布置2道护底带;通过试验论证了护底带的4个高程,建议护底带高程为85.5 m,并对护底带高程进一步细化论证;优化后的方案可使引航道口至黄家港段的水位略超过调水前的水平,其中引航道口处最大水位抬高0.06 m。

长江南京以下深水航道野外观测数据服务平台建设

为提升深水航道数据资源的采集、融合、分析及应用能力,在南京长江深水航道水沙环境与工程安全交通运输行业野外科学观测研究基地进行长江深水航道野外观测数据服务平台建设。服务平台采用B∕S架构,通过物联网、分布式建构等技术手段结合常用网络传输协议连接各数据集群,实现多源异构历史资料的整合与治理、实时监测数据的接入和第三方数据的聚合,开发了数据门户、水运一张图、工程专题、监测大屏、水位预测等专题应用。平台建设实现了以深水航道为主题的数据聚合与共享。

远程控制船舶内河航行风险评价研究

针对远程控制船舶内河航行风险定量评价问题,提出了一种不确定性建模与船模航行试验相结合的风险评价框架,分为模型构建、量化和验证3个部分。在模型构建方面,模型节点来自内河环境、通信、岸端、船端和风险5个方面辨识的船舶远程控制航行风险因素,根据专家经验和航行试验对初始模型结构进行迭代修正,形成了远程控制船舶内河航行风险评价的贝叶斯网络模型;在模型量化方面,为量化父子节点之间线性或非线性关系提出了条件概率计算方法,在内河连续桥区开展船模航行试验,获取了部分根节点的先验概率、航行事故或险情,以及试验人员对航行风险的评价等数据;在模型验证方面,从情景分析、敏感性分析、对比分析3个角度对模型进行了验证。结果表明:在统计的40起航行试验案例中,触碰/碰撞事故占比最高,试验发现了新的失效模式,即控制冲突、程序错误、信号丢失等;构建的贝叶斯网络模型能够有效评价不同情景下航行风险水平,并辨识了与远程控制船舶内河航行风险相关的重要节点。研究结果可以为实现内河船舶远程控制作业模式提供理论依据,也为内河远程控制船舶航行安全提供研究思路。

基于船舶模型的航迹计算法

针对船舶航迹分段和压缩中难以提取船舶特性、船舶模式不清晰和航迹细节遗漏等难题,根据船舶航行特点和船舶“stop-move”模式,提出了直线、转向和停泊3种船舶模式的航迹表示法及航迹模式测试和分割计算法。选取JAVA编程语言实行此计算法,并利用实船航迹数据信息集进行检测。实验结果证明,此计算法可完善保存船舶模式和特性的基础上对船舶航迹进行有效地分段及压缩,可为大量船舶航迹数据的挖掘、查询和分析提供理论依据和研究基础。

基于GNSS水汽和地面假相当位温观测的短时强降水阈值预报方法研究

基于2019年和2020年6—7月GNSS水汽监测网大气可降水量(PWV)资料和并址气象站的地面雨量、温、压、湿等同步观测数据,利用临界成功指数(CSI)和命中率(POD)两个检验指标,探索建立了基于PWV、6小时水汽增量(PWV*)及假相当位温距平(θ_(se)*)的短时强降水阈值预报方法,并利用2021年6—7月降水样本对该预报方法进行检验,结果显示CSI和POD分别为0.167和0.593,其评分高于目前常规业务方法对短时强降水的客观预报评分,其中约48%的短时强降水发生在预警之后的24小时内,约78%发生于48小时内。研究区域内78.6%的短时强降水样本发生在连续15小时PWV*的累积值(∑PWV*)≥75 mm且连续24小时θ_(se)*累积值(∑θ_(se)*)≥30 K的条件下;PWV高值区叠加∑PWV*和∑θ_(se)*的大值区对梅雨期短时强降水以及暴雨发生区域有较好的指示性。

长江下游桥区动态自适应自主航行决策方法

针对长江下游桥区环境复杂且时变,存在特殊航行规则、可航水域受限等问题,提出一种自主航行决策方法。在该类水域,基于数字化交通环境模型,结合导航模型、船舶操纵运动数学模型(MMG)、航向航迹控制方法构建自动航行模型。以航行规则和良好船艺为前提计算可行操纵区间,依靠时序滚动框架消除剩余误差和自适应目标船(TS)机动,求取自主航行决策方案。仿真结果表明:该方法能自适应时变环境,实现自适应多目标避让,并沿推荐航线安全通过,为桥区水域自主航行提供一种自适应的决策方法。

基于云模型的极地航行船舶驾驶员关键行为因素分析

为系统性考虑人为因素对极地航行安全的影响,采用人为因素分析及分类系统和行为影响因子,结合船舶极地航行的实际情景特征,利用调研数据和云模型正向云发生器算法,构建了极地航行船员人为因素分析及分类模型。该模型包含49种驾驶员行为子因素,以识别极地航行船舶驾驶员人因失误的关键行为因子。结果显示:导致极地航行船员人因失误的关键行为因素来自不安全监督、不安全行为的前提条件和不安全行为层级的28个子因素。关键行为因素的识别有助于研究人员和管理者有针对性地采取有效措施,防止人为失误的发生以提高船舶极地航行安全水平。

浅水条件下喷水推进船航态及喷射流形态研究

为了探究浅水条件对喷水推进船航态及喷射流形态的影响,基于数值模拟方法进行不同水深条件下喷水推进船航态及喷射流形态影响规律及机理分析,并构建回归预报模型。采用雷诺时均方程建立喷水推进船自航特性数值模拟方法,开展水深条件对喷水推进船绕流场以及喷射流形态和湍动能分布的影响研究。基于多水深条件下喷水推进船航态和喷口流量数值计算结果,构建船模航态及喷射流形态回归预报模型。研究结果表明:随着水深减小,浅水阻塞效应加剧,船底压差和尾倾角增大,船体周围回流速度和吃水量也增加;船首横波系逐渐增大并与船尾横波系相互干扰,耗散能量增加;喷射流与船尾兴波交汇点随水深减小逐渐前移,径向扩散和旋度增大,推进功率下降,湍动能和水体扰动增强。研究成果可为浅水条件下喷水推进技术应用提供科学依据,提高喷水推进船在复杂水域环境中的效率和安全性。