共查询到20条相似文献，搜索用时 62 毫秒
1.
2.
As a multi-branch estuary system, the Yangtze Estuary presents distinctive characteristics of hydrodynamic processes through co-action among river runoff, tides, wind-waves, and gravitational circulation. To study the pathways of flushing water along all of the estuary's branches and analyze their differences, especially those due to the influence of seawater intrusion and discharge variations, a free surface flow modeling suite TELEMAC-MASCARET involving passive tracers was applied to the Yangtze Estuary and the adjacent waters. The open boundary conditions were provided by the Nao.99 b model(Matsumoto et al., 2000), which was calibrated using observed velocity and salinity data obtained in March 2002. The water age, which was used as the diagnostic tool to study the flushing efficiency of the water body across the estuary, was solved by additional advection-diffusion-reaction equations implemented in the TELEMAC modeling system. The transport properties were investigated under different river discharge scenarios, which represented seasonal impacts; aspects relating to the influence of tide, surface wind stress, and density-induced circulation on age were also investigated. Model results showed that river runoff is one of the dominant factors influencing the spatial distribution of the mean age, while tidal force is another important factor. The horizontal freshwater age distribution demonstrated similarity compared with the salinity distribution; the vertical age distribution resembled the stratification pattern of salinity in all branches where stratification persists. An experimental numerical simulation of tracing saltwater age from the lower reaches of the estuary was conducted, and implicated the connectivity with transport processes of freshwater from upstream. Additionally, a particle tracking algorithm was used to analyze the dynamic characteristics of the four passages. The South Passage and South Channel were found to be significant as main water flow passages, while salinity intrusion in the North Branch was found to cause a return flow that partially joins the South Branch flushing water. 相似文献
3.
SEAWATER INTRUSION TYPES AND REGIONAL DIVISIONS IN THE SOUTHERN COAST OF LAIZHOU BAY 总被引：1，自引：0，他引：1
The southern coast of Laizhou Bay, Bohai Sea, is one of the areas in China most seriously impacted by seawater intrusion. Based on the sources of intruding waterbedies, seawater intrusion can be divided into two types: intrusion of saline water derived from modern seawater, and intrusion of subsurface brine and saline water derived from paleo-seawater in shallow Quaternary sediments. There are some distinct differences in their formation, mechanism and damage. The subsurface brine intrusion is a special type, which can cause very serious disaster. The coastal landform and the Quaternary hydrogeological environment are predominant factors in the classification of seawater intrusion types. Various coastal environments in different coastal sections result in three types of intrusion: seawater intrusion, saline groundwater intrusion, and mixed seawater and saline water intrusion, in the southern coast of Laizhou Bay, which can be divided into four areas: the sea-water intrusion area in the northern Laizhou City coast, the mixed seawater and saline groundwater intrusion area in the Baisha River-Jiaolai River mouth plain area, the mixed seawater and saline groundwater intrusion area in the Weihe River mouth plain area northern Changyi county coast, and the saline ground-water intrusion area in the northern Shouguang plains. 相似文献
4.
Dynamic process simulation with a Savage-Hutter type model for the intrusion of landslide into river 总被引：1，自引：0，他引：1
Natural damming of rivers by mass movements is a very common and potentially dangerous phenomena which has been documented all over the world. In this paper, a two-layer model of Savage-Hutter type is presented to simulate the dynamic procedure for the intrusion of landslide into rivers. The two-layer shallow water system is derived by depth averaging the incompressible Navier-Stokes equations with the hydrostatic assumption. A high order accuracy scheme based on the finite volume method is proposed to solve the presented model equations. Several numerical tests are performed to verify the realiability and feasibility of the proposed model. The numerical results indicate that the proposed method can be competent for simulating the dynamic process of landslide intrusion into the river. The interaction effect between both layers has a significant impact on the landslide movement, water fluctuation and wave propagation. 相似文献
5.
虚拟现实的三维时态GIS模式研究 总被引：3，自引：1，他引：2
三维场景是三维地理信息系统中人机交互的主界面。本系统中包括地球和流域两个场景,其中流域的两大基本要素是地形和河道。系统将DEM地形和河网表达在三维场景中,通过读取连续时段的河网格网数据进行水流的动态演示,体现时态GIS的历史回溯性;同时与虚拟现实结合,在场景中实时增加模型,并可以对其选择,变换,删除等。最后实现了对地形任意点的位置查询和不同时刻河流各格网点的水位、流速和流向的查询等功能,具备良好的人机交互性。 相似文献
6.
7.
赵建 《中国地理科学(英文版)》1999,9(2):151-158
１ＴＨＥＨＹＤＲＯＣＨＥＭＩＣＡＬＩＮＤＥＸＥＳＦＯＲＴＨＥＪＵＤＧＥＭＥＮＴＯＮＳＥＡＷＡＴＥＲＩＮＴＲＵＳＩＯＮＴｈｅｈｙｄｒｏｃｈｅｍｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｉｓｔｈｅｄｉｒｅｃｔｂａｓｉｓｆｏｒｔｈｅｊｕｄｇｅｍｅｎｔｏｎｓｅａ... 相似文献
8.
以DEM提取流域水系河源的最小误差分析 总被引：2，自引：0，他引：2
目前,以水文模型提取流域水系已成为水文科学研究中的热点问题。但用DEM提取流域水系的方法不能解决流域水系唯一性的问题。故本文在没有流域纸质水系图或遥感数据的前提下,提出以DEM提取流域水系的河源最小误差法,即通过建立实际河源与提取水系河源两点之间的距离误差与网格数大小的相互关系,以两点之间误差最小为原则解决流域水系提取唯一性问题。以晋江流域为例,30m分辨率的数字高程模型(DEM)为基础数据,采用河源最小误差法提取了晋江流域水系。结果表明,最小河流长度为42m时,实际河源与提取水系河源的距离误差达到最小,相应的晋江流域的水系分维值为1.389,表明该法是提取流域水系较合理可行的算法。 相似文献
9.
河网自动综合中Delaunay三角的应用 总被引：7，自引：0，他引：7
在地图数据处理和GIS分析应用中,河网自动综合是制图综合的一个重要组成部分,其中涉及到从双线河向单线河转化的过程及河间距的研究。本文利用Delaunay三角网中的三角形的边连接具有的空间邻近性特点,介绍了用Delaunay三角网结构的骨架线来提取双线河流中轴线及研究河间距量算的方法。 相似文献
10.
海岸带是地球表层物质、能量和信息流通交换最活跃区域之一,具有动态变化的盐度、溶解氧等地球化学梯度,其界面过程体现在大气降水-河水-海水-地下水-沉积物之间的物质循环和能量交换。在人类活动与气候变化双重影响下,海岸带面临着气候灾害、海岸侵蚀、海水入侵、滨海湿地退化、水体富营养化以及重金属、新型污染物等生态环境问题,成为地球科学和环境科学领域研究的热点。本文围绕海岸带水文-生物地球化学循环、人类活动影响下的海岸带环境问题、海岸带环境对气候变化的响应、海岸带海陆交互界面观测新技术新方法4个方面,综述了国内外研究进展与发展趋势,展望了海陆交互作用及其生态环境效应研究的未来发展方向。 相似文献
11.
蒙古高原地处干旱半干旱地区,河流水系对该区域的资源环境格局及其生态环境影响重大。发源于蒙古国的色楞格河是蒙古高原最主要的水资源来源,准确掌握该流域的水体信息对东北亚地区生态环境问题及资源保护具有重要意义。本文以蒙古高原色楞格河流域为研究对象,基于谷歌地球引擎（Google Earth Engine,GEE）云平台,使用 Sentinel-2 多光谱卫星遥感影像,利用深度神经网络（Deep Neural Network, DNN）方法对色楞格河流域的水体信息进行提取,并与支持向量机方法进行对比;利用全球30 m SRTM数据生成水系分布矢量图,通过空间分析形成河流提取目标区,结合深度神经网络分类结果,绘制蒙古国色楞格河流域2019年河流分布图。研究结果表明：① 该方法能够准确地完成大流域范围内的水体制图,提取结果能够体现色楞格河流域河流的空间分布,且能够减少河流断流、空洞现象;② 深度神经网络模型中批量大小设置为8时,在处理数据速度与精度中达到最优,而神经网络结构中隐含层数达到4层时,在精度评价指标测试数据集上达到0.9666,保证了模型特征挖掘能力;③ 经样本点的验证,结果总体精度达到97.65%,可以满足实际应用需求。本研究预期可以为蒙古高原的水体提取提供方法支持和相关数据支持。 相似文献
12.
流域空间离散化及其对径流过程模拟的影响研究 总被引：1，自引：0，他引：1
任立良 《地球信息科学学报》2000,2(2):11-15
本文分析比较了流域空间离散化的两种途径 :子流域法和网格法 ,并以此对流域径流过程模拟的影响进行了探讨。结果表明空间尺度和时间尺度之间应该是相互关联、相互匹配的 ;时空尺度具体大小的选定要根据研究目的、研究区域的面积、流域下扩建面信息源和模型输入资料的可获性综合考虑。 相似文献
13.
14.
1 ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｅｒｍ“ａｎａｓｔｏｍｏｓｉｎｇｒｉｖｅｒ”ｗａｓｆｉｒｓｔａｐｐｌｉｅｄｂｙＳＣＨＵＭＭ ( 1968) ,ｒｅｆｅｒｒｅｄｔｏｓｔａｂｌｅ ,ｌｏｗｂｅｄ ｌｏａｄ ,ｍｕｌｔｉｐｌｅｃｈａｎｎｅｌｓｙｓｔｅｍｗｉｔｈｌｏｗ ｇｒａｄｉｅｎｔ,ｈｉｇｈｓｉｎｕｏｓｉｔｙａｎｄｓｅｐａｒａｔｅｄｖｅｇｅｔａｔｅｄｉｓｌａｎｄｓ .Ｔｈｉｓｓｐｅｃｉｆｉｃｍｅａｎｉｎｇｏｎ“ａｎａｓｔｏｍｏｓｉｓ”ｗｈｉｃｈｗａｓｆｉｒｓｔｕｓｅｄｂｙＪａｃｋｓｏｎｉｎ 1834ｅｎｄｅｄｔｈｅｓｙ… 相似文献
15.
北秦岭松树沟铬铁矿床三维地质建模及其找矿意义 总被引：1，自引：0，他引：1
北秦岭松树沟超镁铁质岩体位于商丹缝合带北侧、北秦岭构造带南部边缘,是陕西省出露面积最大的超镁铁质岩体,岩体中赋存了小型铬铁矿床,深部是否具有成矿潜力备受关注。松树沟超镁铁质岩体中岩相呈对称分布,结合钻孔与物探资料,推测岩体呈透镜状产出;岩石地球化学数据显示岩体中部橄榄岩相具有变质橄榄岩或阿尔卑斯橄榄岩特征,边部橄榄岩相具有超镁铁质堆晶岩特征;松树沟与西藏罗布莎纯橄榄岩体中铬铁矿的矿物地球化学特征类似,由此提出松树沟超镁铁质岩体具有形成"豆荚状"和层状铬铁矿体的潜力。基于前期勘探获得的343个钻孔资料,通过3DMine软件建立了矿床的三维地质模型,剖析了矿体分布规律、钻孔控制程度、富矿与贫矿赋存部位等。根据贫矿的富集部位、流动构造、岩浆分异程度、化探异常,预测了2个具有深部找矿潜力的地段,并提出了找矿标志与找矿方法,为本区勘查找矿提供思路。 相似文献
16.
Silicon limitation on primary production and its destiny in Jiaozhou Bay, China——Ⅳ：Study on cross-bay transect from estuary to ocean 总被引：1，自引：0，他引：1
The authors analyzed the data collected in the Ecological Station Jiaozhou Bay from May 1991 to November 1994, including 12
seasonal investigations, to determine the characteristics, dynamic cycles and variation trends of the silicate in the bay.
The results indicated that the rivers around Jiaozhou Bay provided abundant supply of silicate to the bay. The silicate concentration
there depended on river flow variation. The horizontal variation of silicate concentration on the transect showed that the
silicate concentration decreased with distance from shorelines. The vertical variation of it showed that silicate sank and
deposited on the sea bottom by phytoplankton uptake and death, and zooplankton excretion. In this way, silicon would endlessly
be transferred from terrestrial sources to the sea bottom. The silicon took up by phytoplankton and by other biogeochemical
processes led to insufficient silicon supply for phytoplankton growth. In this paper, a 2D dynamic model of river flow versus
silicate concentration was established by which silicate concentrations of 0.028–0.062 μmol/L in seawater was yielded by inputting
certain seasonal unit river flows (m3/s), or in other words, the silicate supply rate; and when the unit river flow was set to zero, meaning no river input, the
silicate concentrations were between 0.05–0.69 μmol/L in the bay. In terms of the silicate supply rate, Jiaozhou Bay was divided
into three parts. The division shows a given river flow could generate several different silicon levels in corresponding regions,
so as to the silicon-limitation levels to the phytoplankton in these regions. Another dynamic model of river flow versus primary
production was set up by which the phytoplankton primary production of 5.21–15.55 (mgC/m2·d)/(m3/s) were obtained in our case at unit river flow values via silicate concentration or primary production conversion rate.
Similarly, the values of primary production of 121.98–195.33 (mgC/m2·d) were achieved at zero unit river flow condition. A primary production conversion rate reflects the sensitivity to silicon
depletion so as to different phytoplankton primary production and silicon requirements by different phytoplankton assemblages
in different marine areas. In addition, the authors differentiated two equations (Eqs. 1 and 2) in the models to obtain the
river flow variation that determines the silicate concentration variation, and in turn, the variation of primary production.
These results proved further that nutrient silicon is a limiting factor for phytoplankton growth.
This study was funded by NSFC (No. 40036010), and the Director's Fund of the Beihai Sea Monitoring Center, the State Oceanic
Administration. 相似文献
17.
Roads are conspicuous components in a river landscape;however,their impacts on river landscape patterns and ecological processes have not been systematically studied at the watershed scale.In this paper,the Lancang River Valley in Yunnan Province,China was selected as a case to study road lateral disconnection and crossing impacts and identify river-road network interaction.This study was primarily focused on the road impacts on soil erosion intensity and patch density by using GIS analysis at different scales and explored their distribution with terrain factors.The results showed that river density revealed spatial autocorrelation although both of the roads and rivers were distributed unevenly in the valley.The lateral road(road curvature≥1.1)proportion correlated with soil erosion intensity(p 0.01)at the small sub-basin scale.Soil erosion intensity decreased with increasing lateral road buffer width.Light erosion generally accounted for a large proportion of the erosion in the lateral road buffer zones(1.0–4.0 km),while higher class lateral roads imposed greater impacts on soil erosion than lower class roads,which primarily had a moderate erosion level.In addition,the results of road-river intersection density indicated that road crossing impacts were significantly correlated with patch density at the small sub-basin scale.Topography factor(percent of slope25°in each sub-basin had a close relationship with the ratio of total length of road line with curvature value≥1.1 to the total number of intersections.The correlation(p 0.01)between road impacts and terrain factor revealed that topography affected the road impact distribution in the Lancang River Valley. 相似文献
18.
数字城市的基础地理数据库正在由传统的二维形式向三维形式转变,建设城市三维模型已成为数字城市工程的重要基础工作。作为城市三维模型的核心构成部分,建筑模型的数量巨大,生产成本高。数字摄影测量技术为建筑矢量数据的采集提供了有效途径,但要进一步缩减三维建模的工作量,需要对基于矢量线条的建筑结构识别、建筑体面构造以及各种复杂建筑构型等方法和算法进行研究,并开发辅助人工的建筑三维建模软件系统。该文以数字城市测量提取的建筑结构线为基础,对计算机三维建模中涉及的关键算法进行研究,提出了一种城市建筑三维快速建模的方法。 相似文献
19.
为有效提高三角洲沉积相模拟的精度,以塔河T区为例,应用地震、岩心及测井资料,通过定量评估可容纳空间、物源供给和沉积搬运之间复杂的关系,建立该地区辫状河三角洲砂体沉积正演模型,并将此转化为多点地质统计模拟的三维训练图像,进行研究区辫状河三角洲多点地质统计模拟。研究表明:辫状河三角洲砂体分布受沉积正演模拟控制参数影响,其中砂质供应体积分数、沉积物流入比例、水流载荷量及洪水期间隔均属于强敏感性参数,对研究区三角洲砂体分布影响较大;砂岩含量沉积正演模型体现了辫状河三角洲退积式沉积过程,符合研究区沉积特征,将其转化为三维训练图像,多点地质统计模拟结果在三维空间具有受训练图像约束的特征,体现了训练图像所反映的相带接触关系,并且与钻井认识一致。所提出的这种新的获取三角洲沉积体三维训练图像的方法,综合了沉积正演模拟与多点地质统计模拟的优势,取得了一定的应用效果,对类似沉积体三维地质建模具有一定的借鉴作用。 相似文献
20.
开展三维地质建模的目标,不应当只是实现地质体框架的可视化表达,而应当同时实现地质大数据的聚合、管理、挖掘、分析和共享。然而,传统的方法和技术难以实现顾及地质语义的结构-属性一体化三维地质建模与耦合表达。多点地质统计学方法虽然便于多源数据、地质先验知识、结构-属性的融合建模,却仍然受到数据结构表达能力不足、三维训练图像难以获取和非平稳现象的限制。面向地质大数据集成与管理的要求,详细讨论了三维地质建模中的空间数据模型、基于多点地质统计学的结构-属性一体化集成建模方法、以及基于三维地质模型的地质大数据集成与管理的框架与模式。发展新型的面向地质结构-属性耦合表达的统一空间数据模型,以及知识驱动与数据驱动协同的三维地质结构-属性一体化集成建模技术体系,着力构建出地质大数据的聚合、集成、管理、挖掘和分析的可视化环境与操作平台,是未来三维地质建模领域的研究热点和前沿方向。 相似文献