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991.
以盐城保护区核心区为例,利用2002年野外高程测量数据,运用Kriging和TIN两种不同思想的插值方法对研究区DEM的构建与精度评估两个问题展开研究.研究结果表明:1)Kriging插值验证显示:均差接近于0,均方根标准误差接近于1.证明采用Kriging插值同时考虑数据本身约束性条件的模型是可行的.同时,运用等高线和等高点数据生成的TIN,效果同样比较理想.2)对两种DEM进行了精度评估,数据显示误差都在可控范围之内.其中Grid-DEM的绝对误差最大值为0.162 m,平均绝对误差为0.063 m,平均相对误差为4.20%;而TIN-DEM的最大值仅为0.028 m,平均绝对误差和平均相对误差只有0.005 m和0.36%.3)在对两种DEM的比较中发现:无论是绝对误差还是相对误差,Grid-DEM都要远高于TIN-DEM,两者最大值相差0.134 m;在受人类干扰较强以及经常受潮汐影响而处于不断变化的区域,Grid插值要明显差于TIN插值.但从DEM表面整体光滑度来看,Grid-DEM却要优于TIN-DEM. 相似文献
992.
993.
华南沿海地区,由于历史原因,目前存在的深度基准面繁多,关系复杂,为了解其含义,来源、历史沿革及革及其变化规律,本文作了较为详细的介绍,并进行了初步的推算,对海洋工程的规划,设计、施工等,具有重要的实际意义。 相似文献
994.
文中认为在东濮凹陷中自沙河街组四段沉积中晚期开始,海水随着海面升降,间歇性地进入由北东向的兰聊断裂和长垣断裂构成的古河谷。高位期,海水以相对暂时性抬高的形式,淹没本区,致使凹陷南部成为向东南或南开口的河口湾,构成盐湖沉积的先期沉积环境,到低位期,海水退出凹陷区,部分海水因 受东西向同沉积走滑断裂(高平集-习城集一线)高地的阻隔而潴留,局限在高平集-习城集断层至文明寨-范县断层的同沉积构造凹陷,潴留海水蒸发、浓缩,形成盐类。在较深的凹地,受陆源淡水的影响较小,卤水浓度相对较高,那里依次沉积了具有深水沉积特点的碳酸盐岩、石膏、石盐等;而在水体较浅的凹地,(如砂砰、泥坪环境),那里易受季节性洪水影响,卤水淡化,沉积了具有明显浅水特征的灰质泥岩、泥膏岩等。 相似文献
995.
热带气旋活动以及由此产生的风暴潮和强降雨对南海及周边沿海地区社会经济构成巨大威胁。对器测记录之前全新世热带气旋的研究有助于准确预测全球变暖背景下热带气旋活动的变化趋势。本文利用南沙群岛安乐礁潟湖沉积物重建了小冰期以来准年分辨率的热带气旋活动,共识别28个风暴事件层。研究表明,小冰期以来,南沙群岛安乐礁热带气旋活动在年代际到百年尺度上频繁变化,发育两个主要的风暴活跃期。在小冰期早期(AD1471—1620)经历了最为强烈的风暴活跃期,另一个风暴活跃期位于现代暖期的AD 1930—1960,风暴活动虽有所加强,但明显低于小冰期早期。与同期永暑礁重建结果的对比表明,热带气旋活动存在明显的时空差异性,更多来自相近区域的高分辨率风暴记录可有效降低古风暴活动重建的不确定性,提高重建记录的准确度。 相似文献
996.
Groundwater in coastal areas is commonly disturbed by tidal fluctuations. A two‐dimensional analytical solution is derived to describe the groundwater fluctuation in a leaky confined aquifer system near open tidal water under the assumption that the groundwater head in the confined aquifer fluctuates in response to sea tide whereas that of the overlying unconfined aquifer remains constant. The analytical solution presented here is an extension of the solution by Sun for two‐dimensional groundwater flow in a confined aquifer and the solution by Jiao and Tang for one‐dimensional groundwater flow in a leaky confined aquifer. The analytical solution is compared with a two‐dimensional finite difference solution. On the basis of the analytical solution, the groundwater head distribution in a leaky confined aquifer in response to tidal boundaries is examined and the influence of leakage on groundwater fluctuation is discussed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
997.
The results of field measurements conducted in a small (19·37 ha) agricultural watershed on the North Carolina coastal plain during the summer of 1996 are presented. The objective of the study was to develop a more complete understanding of basin response in the region with respect to stormflow generation and, in particular, to identify the processes that determine storm runoff and the conditions under which such processes occur. Twenty‐four storm events were monitored, including two tropical storm systems and two hurricanes. The data demonstrate considerable spatial and temporal heterogeneity in runoff generation within the watershed. Surface flowpaths, in the form of Hortonian overland flow and saturation overland flow, were found to be the dominant runoff processes during the storm events measured. The hillslope flowpaths had the same response time as the basin streamflow, but significantly shorter time of rise and lag times. The importance of Hortonian flow in a basin with sandy, permeable soils, as well as the rapid stormflow response in a low‐relief area with a humid climate, was contrary to expectations. This, coupled with the contingency of runoff response, suggests that it may be difficult to generalize about runoff generation mechanisms in broad terms, and that a synoptic approach may be more appropriate. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
998.
利用遥感资料进行海岸带环境动态变化监测具有快速准确的优点。随着高空间分辨遥感技术的发展,遥感技术已成为海岸带资源环境管理中一个重要的信息获取手段。海岸带环境遥感信息系统以遥感数据应用为核心,根据信息产品生产的业务化需求将遥感数据的获取、预处理、专题信息提取、遥感专题图产品制作的整个过程有机地集成为一体,实现了遥感数据处理、遥感信息提取、专题信息综合、专题产品制作等信息产品的业务化生产。海岸带环境遥感信息系统由硬件集成、软件集成、功能集成、数据集成等4方面内容组成,对系统集成的优缺点作了分析和探讨,并展望了其应用前景。 相似文献
999.
Occurrence and distribution of vibrios in fishes and shellfishes in coastal waters of Hong Kong 总被引:1,自引:0,他引:1
Xu Huaishu Li Jun Phyllis Brayton Norman Y. S. Woo David Swartz Zhang Shuting Rita R. Colwell 《海洋学报(英文版)》1998,17(4):545-553
INTRODUCTIONTheoccurrenceanddistributionofhalophilicvibriosinthecoastalwatersofHongKonghasbeenrePorted(Chanetal.,l986).Theresultsshowedthatvibrioswerepresentduringthesum-mermonthsinHongKongcoastalwatersatconcentrationsof9oto67ooind./cm3,accountingo.4l%~4o%ofthetotalbacterialPOpulationofthe48isolatesexaminedindetail.Theyob-servedV.Paraheamolyticus,V.harvha,V.vulnfficus,V.camPbelliandV.fiuvialis.Becausemanyofthevibri0species,includingsome0ftheisolatesbyChanetal.(1986)fromHongKongwate… 相似文献
1000.
F.J Cook W Hicks E.A Gardner G.D Carlin D.W Froggatt 《Marine pollution bulletin》2000,41(7-12):319-326
Disturbed acid sulphate soils are potent sources of acidity in coastal waterways. Monitoring studies of the drainage water for sites at East Trinity, Cairns and Pimpama, south-east Queensland indicate that considerable acidity is found in the drainage water from these sites. Hydrogen (H+), ferrous (Fe2+) and aluminium (Al) ions are the dominant acid cations involved. When drainage water is mixed with fresh or marine waters the effect of H+ on acidity generation is immediate. Aluminium can release acidity on hydrolysis, while the oxidation of Fe2+ to Fe3+ both acidifies and removes dissolved oxygen from the water. Strongly acidic waters with low levels of dissolved oxygen concentration are undesirable for most forms of aquatic life. Export of acidity from acid sulphate soil is likely to have a major effect on inshore fisheries and breeding grounds especially in periods of flood following drought or periods of low rainfall, where large volumes of acidity can be flushed/leached into sensitive aquatic/marine habitats. Impacts may include low dissolved oxygen, fish kills, epizootic ulceration syndrome and damage to oysters. During the processes of oxidation and hydrolysis, iron and aluminium flocs form, that can smother benthic communities. Heavy metals are found in the drainage water at elevated levels and may also be of concern for aquatic organisms. Chronic effects such as habitat degradation, mortality of marine worms, bivalves, invasion of acid tolerant species (both plant and animal) and avoidance of habitat have been documented elsewhere. These areas require further research. 相似文献