建立三维数字长江模型的关键技术探讨

在过去的50余年中,已积累了大量的长江全程水道地形、水文、泥沙资料,为了反映长江水文变化过程的时空动态特征,需要开发能实现三维显示的软件用于水文模拟和水资源管理。中国地质大学信息研究所和长江水利委员会水文局联合开发了"长江水文泥沙信息分析管理系统(GeoHydrology)",并利用其中的三维可视化子系统建立了一套三维数字长江模型,实现了长江水文泥沙及河道原型观测和分析信息的三维可视化。就其中涉及的关键技术及其实现方法进行探讨。

长江防洪模型量测控制系统的设计与应用

长江防洪模型量测控制系统设计由流量自动控制、水位测量、尾门水位控制、流速流态测量、加沙量控制、动床河道地形测量、影像监控设施等量测子系统组成。对各子系统的工作原理、控制方式、技术特性以及应用效果进行了简要介绍。由于应用计算机及网络技术和高性能仪器,系统实现了模型试验各种参数的实时采集、控制与数据处理,成为测控功能较为完善的模型自动化量测控制系统。长江防洪模型的运行表明:量测控制系统能够满足试验的需求,大大提高了测量控制精度和工作效率,缩短了模型试验周期,不仅提高了试验量测控制水平,也提升了模型科研整体水平,促进了研究成果的突破和创新。

虚拟仿真系统在长江防洪模型项目中的应用

虚拟仿真系统是利用世界银行贷款长江防洪模型项目的主要建设内容之一,是"数字长江"这项复杂系统工程的重要组成部分,对防洪决策具有重要意义。采用虚拟现实技术对长江宜昌至石首河道及防洪模型基地交互式三维可视化系统进行开发,为长江防洪的规划、建设和管理提供辅助平台。防洪模型虚拟仿真系统硬件主要包括计算机主机系统、投影系统、中央控制系统。防洪模型虚拟仿真系统软件主要包括实时三维建模工具—Multigen Creator、专业的三维地形生成工具CTS、实时场景管理/运行软件VegaPrime、SiteBuilder 3D等。

长江防洪实体模型垂线流速相似性研究

根据实测资料,采用3点法、5点法对比计算分析了原型和长江防洪实体模型的垂线平均流速两者间差异,同时比较分析原型与模型流速沿水深分布偏离程度。采用明渠对数流速公式探讨了模型变态后流速沿垂线分布的规律,在此基础上提出了长江防洪实体模型垂线平均流速与相对水深某位置处点流速的关系,观测资料分析表明,模型相对水深为0.6处的点水深处流速与垂线平均流速基本一致。

时间变态对模型水流运动相似影响试验研究

利用长江防洪模型上荆江河段,以不同时间变率作为控制方式对上荆江2003年9月1日至9月30日实测水文过程进行模拟,测量了模型入流、尾水、沿程水位、断面平均流速变化过程等。研究了上荆江模型在不同时间变率下沿程水位、流量、平均流速与原型相似的程度并对偏差产生的原因进行分析,在此基础上对尾门滞后控制方式如何提高试验精度进行了研究。

荆江河道水流运动特性研究

利用长江防洪实体模型,全面系统地对荆江不同流量条件下的各水力要素进行测量,并结合三峡水库蓄水以来的水沙、地形资料,分析了荆江河段水流运动的基本规律和近期变化的特点,在此基础上对荆江不同河道整治方案进行了研究,并针对不同河型提出了具体的河势控制措施。研究成果表明:通过试验分析较详细地掌握了荆江水面纵比降、断面宽深比、流速分布及水流动力轴线变化等水力要素变化的特点,揭示了荆江河段水流运动规律,并为河道(航道)整治工程提供了科学依据。

三峡工程运用初期上荆江杨家脑至郝穴河床冲淤变化试验研究

三峡水库修建后,由于水库调蓄作用,进入坝下游荆江河道的水沙过程发生了显著变化,荆江河道产生较明显的冲刷,已引起局部河段的河势调整,将在相当长时期内对两岸堤防、已建护岸工程和河道整治工程及河道的稳定产生不同程度影响,进而影响该地区的防洪、航运、生态与环境以及河流的综合服务功能的正常发挥。利用长江防洪实体动床模型试验研究了三峡工程运用初期不同时期上荆江杨家脑至郝穴河段的冲淤变化过程、冲淤规律、数量及分布,并在此基础上预测河势调整趋势。研究成果为该段河道的治理和河势控制工程规划、设计等提供技术参考。

三峡工程运用初期荆江河段调关弯道冲淤演变试验研究

三峡水库修建后,由于水库调蓄作用,进入坝下游荆江河道的水沙过程发生了显著变化。荆江河道产生较明显的冲刷,已引起局部河段的河势调整,将在相当长时期内对两岸堤防、已建护岸工程和河道整治工程及河道的稳定产生不同程度影响,进而影响该地区的防洪、航运、生态与环境,以及河流的综合服务功能的正常发挥。采用长江防洪实体动床模型试验,研究了三峡工程运用初期不同时期荆江重点险工段调关弯道的冲淤变化过程,并在此基础上预测河势调整趋势。研究成果可为该段河道的治理和河势控制工程规划、设计等提供技术参考。

非恒定流条件下荆江三口分流模拟控制方式研究

长江防洪实体模型是利用世界银行贷款兴建的重大水利科研项目。通过理论分析与试验研究,建立了适合长江防洪实体模型的非恒定流条件下荆江三口分流模拟控制方式。恒定流和非恒定流条件下的验证试验研究表明,该模拟控制方式下荆江三口模型分流流量与分流过程均与原型相似,基本满足试验精度要求。验证后,该模拟控制方式被应用于长江防洪实体模型荆江河段洪水演进特性试验研究。

三峡工程运用初期石首河段冲淤试验及河势控制方案研究

利用长江防洪实体模型动床模型试验,研究了三峡工程运用初期不同时期石首河段的冲淤变化规律,并预测其河势变化趋势;针对该河段出现的新情况进行研究分析,提出了该河段的河势控制方案。研究结果表明:三峡工程蓄水运用至2022年末,该河段总体河势与近期基本一致,依然维持目前新生滩左汊为主汊、左汊内左槽为主河槽的分汊格局,但局部河势仍有一定程度的调整变化。该河段的河势控制初步思路为:对深泓近岸及主流顶冲的险工段采用护岸守护,包括对已建护岸工程的加固及未护段的新护;另外,根据河势调整趋势,对局部洲滩进行守护,以稳定目前较为有利的河势格局或防止其向不利河势方向转化。

Simulated circulations off the Changjiang (Yangtze) River mouth in spring and autumn

The circulations off the Changjiang mouth in May and November were simulated by a three dimension numerical model with monthly averaged parameters of dynamic factors in this paper. The area covers the East China Sea (ECS), Yellow Sea and Bohai Sea. Simulated results show that the circulation off the Changjiang mouth in spring and autumn is mainly the Changjiang runoff and Taiwan Warm Current (TWC). The Changjiang discharge is much larger in May than in November, and the wind is westward in May, and southward in November off the Changjiang mouth. The runoff in May branches in three parts, one eastward flows, the other two flow northward and southward along the Subei and Zhejiang coast respectively. The Changjiang diluted water expands eastward off the mouth, and forms a strong salinity front near the mouth. Surface circulation in autumn is similar to that in winter, the runoff southward flows along the coast, and the northward flowing TWC becomes weaker compared to that in spring and summer. The bottom circulations in May and November are mainly the runoffnear the mouth and the TWC offthe mouth, and the runoff and TWC are greater in May than in November.

Nutrient fluxes in the Changjiang River estuary and adjacent waters——a modified box model approach

To solve nutrient flux and budget among waters with distinct salinity difference for water-salt- nutrient budget, a traditional method is to build a stoichiometrically linked steady state model. However, the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system, as the results would be highly affected by box division in time and space, such as the Changjiang （Yangtze） River estuary （CRE） and adjacent waters （30.75°-31.75°N, 122°10′-123°20′E）. Therefore, we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model （ROMS）. Using data from four cruises in 2005, horizontal, vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model, in which flux fields and the major controlling factors were studied. Results show that the nutrient flux varied greatly in season and space. Water flux outweighs the nutrient concentration in horizontal flux, and upwelling flux outweighs upward diffusion flux in vertical direction （upwelling flux and upward diffusion flux regions overlap largely all the year）. Vertical flux in spring and summer are much greater than that in autumn and winter. The maximum vertical flux for DIP （dissolved inorganic phosphate） occurs in summer. Additional to the fluxes of the ChanNiang River discharge, coastal currents, the Taiwan Warm Current, and the upwelling, nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area. Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas. The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year. In addition, vertical nutrient flux in spring and summer is a main source of DIP. Therefore, the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research.

Development and Validation of National Cotton Cultivar Registration Index Model in Yangtze River Valley

[Objective] Based on the cotton variety high yielding potential, fiber quality traits, disease resistance, and early maturity characters, a cultivar registration index model was developed to simplify the tedious calculation process in national cotton registration procedure, and thus to enhance the practical application of cultivar regis- tration index in cotton breeding ancl cotton recommending. [Method] By means of correlation analysis, partial correlation analysis and path analysis methods, the cor- relation of cotton main properties and their effects on cultivar registration index were explored using the dataset of national cotton regional trials in Yangtze River Valley during 1996-2013. The cultivar registration index model was constructed with step- wise regression statistical technique to ascertain the quantitative relationship of main characters with cultivar registration index, and the regional cotton trial dataset in 2013 was used to validate the model. [Result] Several characters with larger deter- minants to cultivar registration index were screened out,ie. lint yield increase ratio, pro-frost yield ratio, verticillium wilt index, fiber strength, fusarium wilt index and mi- cronaire value. The cultivar registration index model defined the functional relation- ship of cultivar registration index with the selected main characters, among which lint yield increase ratio, fiber strength and micronaire value contributed most to culti- var registration index. The model validation with regional cotton trials in 2013 indi- cated the root mean square error, RMSE was only 2.77, and the variation coeffi- cient was 6.77%, which confirmed the model prediction effect was quite perfect. [Conclusion] The developed cultivar registration index model was reliable enough to simulate the complicated scoring system in cultivar registration procedure, also sim- plified cotton registration process, and enhanced the practicability of the cultivar reg- istration index.

城陵矶综合枢纽对洞庭湖区水位的抬高作用

近年来洞庭湖季节性干旱问题日益突出。为缓解洞庭湖湖区旱情,湖南省和湖北省政府提出了建设城陵矶综合枢纽工程的设想。采用中国水利水电科学研究院的"长江中下游一江两湖水动力模型"计算了该枢纽不同调度方案下洞庭湖湖区水位的抬升变化。结果表明:城陵矶水位每抬高1 m、鹿角站水位雍高约0.93 m、营田站水位雍高约0.90m。城陵矶水位由25.5 m抬高至26 m、26 m抬高至26.5 m、26.5 m抬高至27 m、27 m抬高至27.5 m,相应杨柳潭站水位分别抬高0.17、0.22、0.3和0.4 m,小河咀站水位分别抬高0.06、0.09、0.12和0.20 m。枢纽工程能够在一定程度上解决洞庭湖枯水期缺水问题,水位抬升对湖泊水质和生态系统演化可能造成一定程度的影响。

Direct Climatic Effect of Aerosols and Interdecadal Variations over East Asia Investigated by a Regional Coupled Climate-Chemistry/Aerosol Model

The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols （sulfate, black carbon, and organic carbon） and natural aerosols （soil dust and sea salt）. Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report （IPCC AR5）, whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9- -33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and-12 W m-2 to -24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of-0.8℃ to -1.6℃ over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of-90 mm/year to -150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger per- turbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions.

A Typical Mode of Seasonal Circulation Transition: A Climatic View of the Abrupt Transition from Drought to Flood over the Middle and Lower Reaches of the Yangtze River Valley in the Late Spring and Early Summer of 2011

In this study, the seasonal transition of precipitation over the middle and lower reaches of the Yang-tze River Valley (YRV) from late spring to early summer is investigated. The results show that the seasonal transition of precipitation exhibits multi-modes. One of these modes is characterized by an abrupt transition from drought to flood (ATDF) over the middle and lower reaches of the YRV in the seasonal transition of precipitation. It is shown that the ATDF event from May to June 2011 is simply one prominent case of the ATDF mode. The ATDF mode exhibits an obvious decadal variability. The mode has occurred more frequently since 1979, and its amplitude has apparently strengthened since 1994. From the climatic view, the ATDF mode configures a typical seasonal circulation transition from winter to summer, for which the winter circulations are prolonged, and the summer circulations with the rainy season are built up early over the YRV.

巧用长江干流模型突破思维盲点

针对学生利用板图、板画讨论长江上游的特征时,习惯性地将金沙江河段的"从北往南流"当作"从高往低流"的思维盲点,设计了长江干流简易模型,同时为了帮助学生更好地理解各地理要素之间的联系,对模型进行了升级改造。

Projections of the 21st Century Changjiang-Huaihe River Basin Extreme Precipitation Events

Based on the 1961-1990 observed daily precipitation in the Changjiang-Huaihe River Basin, the NCEP/NCAR reanalysis data, and the HadCM3 model data for IPCC SRES A1B climate projections, the simulation capabilities of the BP-CCA downscaling approach for extreme precipitation indices of the current climate are assessed by applying canonical correlation analysis (CCA). In addition, future extreme precipitation indices in the middle and late 21st century are projected. The results show that simulation capability of the HadCM3 for regional climate characteristics can be effectively improved by the downscaling approach, with 30%-100% reduction of the relative errors of the climatological mean state of extreme precipitation indices. However, the downscaling results still show wetter winter and dryer summer than the observation. Under the SRES A1B emission scenario, frequency and intensity of extreme precipitation events are projected to increase, and the estimated increasing rate is higher for extreme precipitation indices than for mean precipitation index; and in summer than in winter. Extreme precipitations in the middle and late 21st century are expected to increase by 14% and 25% respectively in winter, and by 24% and 32% respectively in summer.

The Prediction of Population of the Yangtze Finless Porpoise

[Objective] The aim was to study the current living situation of Yangtze finless porpoise, and explore the prediction of the number of Yangtze finless porpoise in next few years. [Method] Modified Leslie Model and Siler's Model was applied to estimate the number of Yangtze finless porpoise. [Result] Using the model,Yangtze finless porpoise will extinct in nearly 20 years. [Conclusion] The study provides a cautionary warning of the conservation of the freshwater cetacean species.

Residents' Attitude to Pay for Urban River Restoration:Empirical Evidence from Cities in Yangtze Delta

Public willingness to pay （WTP） for urban rivers res- toration was investigated in Shanghai, Nanjing and Hangzhou in China with a sample of 1,285. The factors influencing positive WTP against zero WTP are analyzed using a binary logit model. The results indicate that income, Huff （residential registration） status, household size, home property ownership, riverfront access, and attitudes toward current water quality arc statistically signifi- cant in the likelihood of positive WTR It is also found that respon- dents without local Huff are less willingness to pay positively in pooled sample and Shanghai sample. In the group holding property right of house but without local Huff is less willingness to pay positively in Hangzhou. Respondents in Nanjing are more will- ingness to pay positively than those in Hangzhou. Most common arguments against to pay for the restoration are ＂government＇s duty＂, ＂low income＂, ＂non-local-Huji＂ and ＂lack of trust in the government in how it spends money＂. The results are generally consistent with the hypothesis and specific situations in China. The findings make some contributions to the non-market valua- tion studies as well as provide useful information for public policy making in China.