共查询到20条相似文献，搜索用时 109 毫秒
1.
Macroalgae have long been used as biological indicators of marine ecosystem health worldwide due to their ecological importance and sensitivity to environmental stress. A number of previous studies have utilized macroalgal communities in monitoring surveys of environmental conditions. This study examined the characteristics and patterns of marine macroalgal communities in the Yellow Sea off the western coast of Korea.Macroalgae were analyzed for the number of species, biomass, and coverage ratio... 相似文献
2.
In this paper,three approachs were developed to find indicator species from the habitat created by coastal structures.These approachs consist of a model of species co-occurrence probability,a model of k-environmental factor probability and a composite model.Simultaneously,a case study was conducted in Hsinchu Fishing Port of north-western Taiwan.Based on the aforementioned models,three primary producer species,Ahnfeltiopsis flabelliformis,Chondrus ocellatus and Sarcodia montagneana,were chosen as the indicator species which had the highest co-occurrence probabilities and showed greater tolerance to more critical environment.It is imperative to understand how the three species under particular co-occurring conditions and environmental factors influence the composition of sessile assemblages in coastal water.The results indicate that for the purpose of increasing biodiversity,these models are feasible to find indicator species of artificial structures,and to help make it possible to design coastal structures based on biological considerations.This study provides an innovative approach for further advanced application in the artificial habitat of coast management. 相似文献
3.
In the present paper, the Holocene sea level changes and coastline shifts in Zhejiang, China are discussed, based on the ancient coastline evidence related with sea level changes and 21 14C dat-ings of shell, peat or mud and wood samples along the Zhejiang coast. The development of Zhejiang coastline during the Holocene period can be divided into four stages. A lot of data of historical period and modern times have shown that tracing coastline shifts back to its source, we have to consider tremendous effects of man's activities besides natural factors, such as elevation and subsidence of the earth crust, sea level changes, supply of sediment, and littoral hydrodynamics. 相似文献
4.
The Chukchi and Beaufort Seas include several important hydrological features： inflow of the Pacific water, Alaska coast current （ ACC ）, the seasonal to perennial sea ice cover, and landfast ice ＇along the Alaskan coast. The dynamics of this coupled ice-ocean system is important for both regional scale oceanography and large-scale global climate change research. A mumber of moorings were deployed in the area by JAMSTEC since 1992, and the data revealed highly variable characteristics of the hydrological environment. A regional high-resolution coupled ice-ocean model of the Chukchi and Beaufort Seas was established to simulate the ice-ocean environment and unique seasonal landfast ice in the coastal Beaufort Sea. The model results reproduced the Beaufort gyre and the ACC. The depthaveraged annual mean ocean currents along the Beaufort Sea coast and shelf hreak compared well with data from four moored ADCPs, but the simulated velocity had smaller standard deviations, which indicate small-scale eddies were frequent in the region. The model resuits captured the sea,real variations of sea ice area as compared with remote sensing data, and the simulated sea ice velocity showed an ahnost stationary area along the Beaufort Sea coast that was similar to the observed landfast ice extent. It is the combined effects of the weak oceanic current near the coast, a prevailing wind with an onshore component, the opposite direction of the ocean current, and the blocking hy the coastline that make the Beaufort Sea coastal areas prone to the formation of landfast ice. 相似文献
5.
TANG Yijie FANG Zhanqiang ZHANG Zaiwang ZHONG Yanting CHEN Kang LIU Benhan FAN Junjie XIONG Tiantian LU Xiaosheng 《海洋学报(英文版)》2014,33(8):62-72
The Sonneratia apetala artificial mangroves in the intertidal zone of Da Wei Bay at Qi’ao Island of Zhu-hai, South China were chosen as the macrofauna succession plots while bare tidal flats of the same size were established as control plots in surrounding interference-free areas. Conventional change indicators of community structure, such as biomass and biodiversity, and indicators, such as exergy and specific exergy, which reflect the information change of overall communities, were used to analyze the succession of macro-fauna communities inS. apetala artificial mangroves. The similarities and differences in variation tendency of the different ecological indicators and their reflected ecological principles were compared. The results showed that from D-1 to D-1275 after plantingS. apetala, the biomass of the macrofauna communities first increased, which was then followed by an increase in the network relationship between the macrofauna communities （analysis of the Pielou evenness index and Shannon-Wiener diversity index）. The system in-formation （specific exergy） increased the slowest. Between D-1460 and D-2370 after plantingS. apetala, there was a decrease in biomass, network structure, and system information in the succession plots. After the decrease in the system information （the specific exergy）, there was a decline in the network relationships （Pielou evenness index and Shannon-Wiener diversity index）. Biomass was the last indicator to decrease. The similarities and differences among the different ecological indicators varied during the succession pro-cess, which reflected the relativity and differences among the indicators. This study suggested that, although the species diversity index can be an effective indicator of two types of changes （network structure and system information）, it was quite clear that species diversity measurement was not suitable for expressing the changes in biomass during the succession process. While exergy and specific exergy can provide useful information 相似文献
6.
Ship floating condition in regular waves is calculated. New equations controlling any ship＇s floating condition are proposed by use of the vector operation. This form is a nonlinear optimization problem which can be solved using the penalty function method with constant coefficients. And the solving process is accelerated by dichotomy. During the solving process, the ship＇s displacement and buoyant centre have been calculated by the integration of the ship surface according to the waterline. The ship surface is described using an accumulative chord length theory in order to determine the displacement, the buoyancy center and the waterline. The draught forming the waterline at each station can be found out by calculating the intersection of the ship surface and the wave surface. The results of an example indicate that this method is exact and efficient. It can calculate the ship floating condition in regular waves as well as simplify the calculation and improve the computational efficiency and the precision of results. 相似文献
7.
Evolution history and trend of the modern Huanghe River Delta 总被引：3，自引：1，他引：2
The evolvement history of modern Huanghe River Delta tidal flat, coastline and underwater terrain were studied based on the analysis of remote sensing images and water depth data. Based on the analysis of seafloor terrain evolution on different historical stages, a formula simulating the erosion and deposition evolvement model of subaqueous Huanghe River Delta slope was proposed, and the evolvement trend of the subaqueous delta terrain was predicted. The result shows that the equilibrium transition zone is near the water depth of 12 m with seabed erosion in shallower water and accumulation in deeper water during the first 150 a after the river channel was deserted. In the meantime, the underwater slope became gentler and the coastal erosion rate became slow gradually. Then, the subaqueous delta slope changed to up concave from upper convex, and the shape of subaqueous delta disappeared. The coast type changed to silt-mud coast about 100-150 a after the river course was deserted. The erosion depth in the foot of the seawall is calculated based on the formula. 相似文献
8.
The distribution and chemical properties of chromophoric dissolved organic matter (CDOM) in the Jiaozhou Bay, China were examined during four cruises in 2010-2011. The influence of freshwater and industrial and municipal sewage along the eastern coast of the bay was clearly evident as CDOM levels (defined as a 305 ), and dissolved organic carbon (DOC) concentrations were well correlated with salinity during all the cruises. Moreover, DOC concentrations were significantly correlated with chlorophyll a concentrations in the surface microlayer as well as in the subsurface water. The concentrations of DOC and CDOM displayed a gradually decreasing trend from the northwestern and eastern coast to the central bay, and the values and gradients of their concentrations on the eastern coast were generally higher than those on the western coast. In addition, CDOM and DOC levels were generally higher in the surface microlayer than in the subsurface water. In comparison with DOC, CDOM exhibited a greater extent of enrichment in the microlayer in each cruise, with average enrichment factor (E F ) values of 1.38 and 1.84, respectively. Four fluorescent components were identified from the surface microlayer and subsurface water samples and could be distinguished as peak A, peak T, peak B and peak M. For all the cruises, peak A levels were higher in the surface microlayer than in the subsurface water. This pattern of variation might be attributed to the terrestrial input. 相似文献
9.
Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh 总被引：1，自引：0，他引：1
In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values. 相似文献
10.
Along the coast of the :"eastern China and on the adjacent shelf, geomorphological, sedimentological and biological evidences, related to ancient strandline, were found, and dated by radiocarbon method. In this paper, the curve and model of sea level changes during the past 20,000 years are established. 相似文献
11.
12.
中国大陆海岸线近30 a的时空变化分析 总被引：8，自引：5，他引：3
基于遥感和地理信息系统的方法与技术,以1980、1990、2000和2010年4个时期为特征年,对近30年来我国大陆海岸线时空变化特征进行了分析研究。结果显示:（1）海岸类型转化显著,人工岸线所占比例由1980年的24.6%上升到2010年的56.1%;（2）海岸线变化呈现显著区域特征,变化较剧烈的区域集中在珠江口岸段、长江口-杭州湾岸段、海州湾-吕四段、滦河口-潍河口段及辽河口-葫芦岛港段;（3）3个时期相比,海岸开发由早期的围垦养殖向后期的城镇建设和海洋运输开发方式转变,并且这种转换方式在南方早于北方。 相似文献
13.
近40 a 来三门湾海岸线时空变化遥感监测与分析 总被引：3，自引：0，他引：3
了解岸线的变化对海岸开发利用有重要意义。本文以Landsat MSS、TM、ETM+、OLI影像为主要数据源,采用人机交互的方式提取1973~2013年的4期三门湾大陆岸线,获取岸线长度以及陆域变化面积等信息,并以县级市(象山县、宁海县、三门县)为单位分段分析岸线时空变化特征。在此基础上,结合研究区新增土地利用类型的解译结果,对三门湾地区海岸开发方式进行系统分析。结果表明:1973~2013年三门湾岸线总体向海推进,总长度减少40.18 km,沿岸陆域面积增加155.89 km2,其中2000~2013年岸线向海扩张最为显著,近40 a来,在沿海三县中,宁海县岸段岸线变迁最为剧烈;海岸人为开发是岸线变化的主导因素,且开发方式时间异质性显著:早期以围垦造田、堵港蓄淡为主,20世纪80年代后期至20世纪末,偏重围垦养殖,进入21世纪,开发规模大幅增长,围垦造田和养殖依然是海岸开发的主要方式,同时城镇、工业建设等围填海规模迅增,港口码头建设也加快了步伐,海岸开发方式呈现多样化。 相似文献
14.
海岸线对于海岸带保护与管理具有重要意义。海岸线现场测绘施测周期长且在地形复杂的区域施测难度大,基于遥感影像的海岸线判绘对解译人员的要求高,难以获取严格意义的海岸线。针对上述问题,本文提出一种基于机载LiDAR与潮汐推算的自然岸线遥感提取方法:基于机载LiDAR系统获取的航空正射影像解译瞬时水边线,应用LiDAR系统提取的DEM和建立的高程系统转换模型,通过潮汐数据推算研究区域的海岸线。通过与“908专项”航空遥感调查岸线结果比对,按本文方法所提取的3种自然岸线(砂质岸线、基岩岸线和淤泥质岸线)的均方根误差分别为1.66,5.23和32.48 m。结果表明,该方法可用于砂质岸线和基岩岸线的提取,且具有无需开展现场测量工作的优势,可提高海岸线提取的效率。 相似文献
15.
基于多时相GF-1和Landsat影像的连云港市44年海岸线遥感监测与演变分析 总被引：1，自引：0，他引：1
海岸线的动态变化监测可为海岸带防护、海岸带资源开发利用和可持续发展过程中的决策支持提供理论支撑。文中基于1973-2017年覆盖连云港市的Landsat系列和GF系列卫星影像数据,结合海岸线分类体系,提取了连云港市10期海岸线信息,并分析了海岸线演变特征及其成因。结果表明:(1) 2017年连云港市海岸线总长度为205.90 km,主要岸线类型为建设围堤和港口岸线,两类岸线总长为120.52 km,占总岸线长度的58.53%;(2) 1973-2017年连云港市海岸线长度整体呈现增长态势,44年间海岸线长度共增长了57.17 km,年增长率约为1.3 km/a。连云港市海岸线主要增长的岸线类型为建设围堤、港口岸线和生物岸线;(3) 44年间,连云港市海岸变化主要的海岸线类型为粉砂淤泥质岸线、生物岸线、港口岸线、建设围堤和盐田围堤;(4) 2017年连云港市自然岸线长度为69.15 km,占总岸线长度的33.6%,44年间,自然岸线长度减少了28.8km,年减少率为0.65 km/a。自然岸线减少的原因主要为养殖业发展、城市扩张建设和港口建设。 相似文献
16.
准确提取海岸水边线是海岸线变迁研究中必不可少的基本工作。本文以海南省陵水黎族自治县2016年的GF-2影像为数据源,在大气校正和正射校正等预处理的基础上,结合数学形态学处理等方法,采用NDWI（Normalized Difference Water Index）阈值法、ISOADTA（Iterative Self-Organizing Data Analysis Technique Algorithm）、SVM（Support Vector Machine）和面向对象法（Object-Oriented Classification,OOC）等四种不同方法来对海岸水边线进行提取,并对其提取结果进行定性和定量评估,进而分析比较了这四种方法在提取人工海岸、砂质海岸和基岩海岸等三种不同海岸类型的水边线时的提取效果和提取精度。结果表明,SVM方法在三种海岸水边线上的总体提取效果最好,总体提取精度最高。 相似文献
17.
海岸线是海洋的重要组成部分,对于海域管理具有重要意义。本文根据岸线位置确定原理,即将多时相瞬时水边线上边界近似作为海岸线,提出了一种基于多时相水边线的海岸线自动提取方法,该方法应用区域生长与边缘检测相结合的方法提取瞬时水边线,然后采用海岸线自动判别算法进行海岸线的提取。首先计算归一化水体指数（normalized difference water index,NDWI）图像,利用区域生长算法进行海陆分割,得到海陆分割二值图;然后利用Canny边缘检测对海陆分割结果进行边缘检测,得到瞬时水边线;最后利用海岸线自动判别算法得到多时相瞬时水边线上界作为海岸线。本文以马六甲海峡部分海岸作为研究区域,应用多期Landsat 8遥感影像进行了海岸线提取和分析。为验证海岸线提取精度,对获取时间接近高潮时的一景哨兵二号影像进行目视解译得到人工解译的海岸线,与本文提取海岸线进行对比。结果显示,本文算法得到的海岸线平均偏移量和均方根误差分别为21.01 m和21.96 m,能够满足30 m分辨率遥感图像的精度要求,相比采用单景影像提取海岸线,精度有明显提高。 相似文献
18.
Waterline technique based on satellite remote sensing is potentially one of the most effective tools for studying changes in tidal flat environment and coastlines. However, multi-temporal waterlines obtained from satellite images are often difficult to compare directly because fluctuant tidal conditions may produce different elevation of waterlines. To overcome the difficulty, this study developed a comparable waterline solution to estimate active lateral evolutions using TM satellite images at different tide conditions. Owing to the dynamic properties, the Yangtze River mouth was selected as the case example to test the suitability of the approach, and totally four time slices were partitioned during 1987–2004 for investigating coastline changes. The first step of this technique is to digitize waterlines with various elevations labeling in a time slice. In the second step, the waterlines were merged to generate DEMs and contour maps using the linear gridding interpolation method. In the last step, any interested contour line may be extracted from DEMs and used for comparison of tideland changes. To evaluate the errors in digitizing and interpolation process, quantitative checks were examined after the DEMs were constructed. In order to monitoring the rate of coastline spread, a proposed approach for estimating mean coastline spread distance between two time spans is developed in this paper. To conclude, this work demonstrates the importance of TM/ETM images to provide high-frequency historical topography and morphodynamics information for coastal monitoring and evaluation. 相似文献
19.
分维数是反映海岸线复杂程度的客观依据。结合国内外海岸线分形研究进展,本文以漠阳江入海口附近海域为研究区,基于Landsat 8 OLI遥感影像对研究区域提取瞬时水边线,并利用潮汐数据进行校正得到海岸线;利用Fractal Fox2.0计算获得该海岸线的分维数为1.071;通过对研究区的分形机制分析,认为漠阳江附近的断裂构造对海岸起宏观控制作用,从而对海岸线的分维值也起了决定作用。根据断裂体系模型计算得到西侧海岸线的理论分维值为1.089,而对数螺线模型计算得到东侧海岸线的分维值为1.171;实际分维值相对理论值偏小,说明海岸带的沉积与侵蚀影响了分维值。此外,根据本区海岸侵蚀原因的分析,对分维机制进行了探究,初步论证的分维值大小可为海岸的冲淤变化研究提供参考。 相似文献
20.
1984～2012年海州湾海岸线时空演变研究 总被引：4，自引：2，他引：2
以Landsat影像为数据源, 通过改进归一化水体指数、二值化、潮位校正模型提取海岸线, 使用数字海岸线分析系统(Digital Shoreline Analysis System, DSAS), 对1984～2012年海州湾海岸线的时空演变进行了研究。结果表明, 1984～2012年间海州湾海岸线整体以4.29 m/a向海洋推进, 其中, 48%的海岸出现侵蚀, 侵蚀速率为22.83 m/a, 侵蚀现象主要出现在大堤修建前的部分粉砂淤泥质海岸。52%的海岸出现淤积, 淤积速率为25.90 m/a, 淤积现象主要出现在人工海岸、河口海岸和受大堤影响的粉砂淤泥质海岸。海岸线时空演变研究有利于科学地规划、开发和管理海洋及其沿岸空间资源, 并保证其环境及经济的可持续发展。 相似文献