基于World Wind的鄱阳湖水位动态变化仿真系统研究

引用本文

戚晓明, 杜培军, 汪迎春, 金菊良, 徐善健. .基于World Wind的鄱阳湖水位动态变化仿真系统研究[J]. 国土资源遥感, 2012,24(2): 105-109
QI Xiao-ming, DU Pei-jun, WANG Ying-chun, JIN Ju-liang, XU Shan-jian. .Simulation Research on the Water Level of the Poyang Lake Based on World Wind Technology[J]. REMOTE SENSING FOR LAND & RESOURCES,2012,24(2): 105-109 复制到剪切板

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《国土资源遥感》编辑部

基于World Wind的鄱阳湖水位动态变化仿真系统研究

戚晓明^1,², 杜培军², 汪迎春^2,³, 金菊良⁴, 徐善健¹

1.蚌埠学院计算机科学与技术系,蚌埠 233000

2.中国矿业大学地理信息与遥感科学系,徐州 221116

3.河海大学水文水资源与水利工程科学国家重点实验室,南京 210098

4.合肥工业大学土木与水利工程学院,合肥 230009

第一作者简介: 戚晓明(1975-),男,副教授,博士后,主要从事水文水资源和地理信息系统研究。E-mail: qixiaoming888@sina.com。

收稿日期: 2011-07-08

基金: 国家自然科学基金项目(编号: 41001292)、水利部公益性行业科研专项经费项目(编号: 201001043)及安徽省教育厅自然科学研究项目(编号: KJ2009B131)共同资助

摘要

World Wind是由美国宇航局(NASA)开发的三维地理信息系统,也是一款可提供丰富数据的数字地球平台,如何将多源数据实现紧密型二三维耦合是基于World Wind开发专业系统需要解决的重要问题。在.NET开发环境下,以World Wind为仿真内核,开发了水位仿真系统,研究了二三维数据耦合技术,实现了环鄱阳湖生态经济开发区的湖区与航道淹没分析和三维漫游。结果表明,仿真系统流畅地实现了任意点地形高程、水位、水深和航道级别等信息的实时查询,仿真了不同控制水位条件下的鄱阳湖区淹没范围,仿真结果能够服务于鄱阳湖水利枢纽的水位调控决策; 该仿真系统在湖泊干旱特征水位等确定中也具有重要的应用价值。

关键词: 湖泊水位仿真系统; 控制水位; 淹没范围; 鄱阳湖; World Wind; GIS

中图分类号:TP751.1 文献标志码:A 文章编号:1001-070X(2012)02-0105-05 doi: 10.6046/gtzyyg.2012.02.19

Simulation Research on the Water Level of the Poyang Lake Based on World Wind Technology

QI Xiao-ming^1,², DU Pei-jun², WANG Ying-chun^2,³, JIN Ju-liang⁴, XU Shan-jian¹

1.Computer Science and Technology Department of Bengbu College, Bengbu 233000,China

2.Department of Remote Sensing and Geographical Information Science, China University of Mining and Technology, Xuzhou 221116, China

3.Hydrology and Water Resources and Hydraulic Engineering Laboratory, Hohai University, Nanjing 210098, China

4.School of Civil Engineering, Hefei University of Technology, Hefei 230009, China

Abstract

World Wind is an open source (released under the NASA license) virtual globe developed by NASA. The program provides a platform for digital earth and 3D GIS. The realization of the compacted 2-3D coupling of multi-source data is one of the problems in the process of developing professional system based on World Wind. In the .Net development environment, taking World Wind as the simulation kernel, the authors developed the water level simulation plug-in, studied the 2-3D coupling of data technology, and realized the lake & channels’ flood inundation risk analysis and 3D roaming of the Poyang ecological economic development zone. The results show that the simulation system can realize smoothly the real-time information query at any point in such aspects as terrain elevation, water level and submerged depth, and navigation level. The submerged range of the Poyang Lake is also simulated under different water-control conditions. The results can serve the decision-making regulation of Poyang Lake water conservancy hub.

Keyword: simulation of Poyang Lake’s water level; control water; submerged scope; Poyang Lake; World Wind; GIS

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0 引言

地形三维可视化技术研究的关键问题是三维地形模型的管理、调度与实时渲染, 以提高地形实时显示速度并达到视觉效果的最佳平衡。国内外学者对大地形建模和仿真技术做了大量的研究, 综合运用了地形多分辨率表示法、层次细节载入LOD(level of detail)控制和地形生成算法等^{[1, 2]}。近年来出现的Google Earth和World Wind等数字地球平台都以大量的空间数据服务为支撑, 实现了多维数据在地球模型中的可视化。World Wind是一款由NASA开发的三维地理信息系统, 该系统利用Landsat 7, SRTM, MODIS等多种卫星遥感数据, 将卫星图像与SRTM数字高程模型叠加在一起, 实现三维地球仿真^{[3, 4]}。World Wind是采用C#语言编写的开源软件, 研究人员能够自由修改源代码, 扩展其功能和样式, 在科学、教育和政府等行业应用中都有非常大的潜力^[5]。

湖泊的水文过程决定了湖泊生态系统的结构和功能, 水位变动是影响湖泊生态系统状态长期变化的最主要因素^[5]。鄱阳湖是中国最大的淡水湖, 是国际重要湿地和长江干流重要的调蓄性湖泊。本文针对鄱阳湖水利枢纽不同控制水位淹没范围、对港口吞吐量和候鸟栖息地影响等问题, 基于World Wind软件开发了鄱阳湖水位动态变化仿真系统, 这有利于鄱阳湖水利枢纽水位调控的决策需求。

1 研究区概况

鄱阳湖位于江西省的北部、长江中下游南岸, 是中国最大的淡水湖泊。鄱阳湖承纳赣江、抚河、信江、饶河、修河5大江河及清丰山溪、博阳河、漳田河、潼津河等区间来水, 经调蓄后由湖口注入长江, 是一个过水性、吞吐型的湖泊, 鄱阳湖水系流域面积16.22万km², 最大丰水期面积约5 100 km²。鄱阳湖为季节性湖泊, 年内水位变幅巨大, 形成了大量的滩地、沼泽和沙洲, 是我国重要的湿地生态系统。水位高时以湖泊为主体, 水位低时以沼泽为主体, 呈现水陆相交替出现的生态景观。夏季的7月与冬季的1月水位相差多年平均为12 m左右。水位和水域面积的变化造成鄱阳湖天然湿地各类型之间的动态变化^[9]。南昌是江西省的省会, 而南昌港则是江西省的枢纽港, 在全省处于航运中心的地位^{[10, 11]}, 鄱阳湖水利枢纽工程对南昌港港口岸线资源影响主要取决于鄱阳湖区水位的控制情况, 鄱阳湖地区的水系及城镇分布情况如图1所示。

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	图1 鄱阳湖地区水系分布图Fig.1 Distribution of river system of Poyang lake

2 湖泊水位仿真系统的研制与实现

2.1 功能设计

鄱阳湖水位动态变化仿真系统是收集、存储、管理、综合分析和处理空间信息的软件系统, 重点强调和突出以下功能:

1) 人机交互。仿真系统简单直观, 方便用户操作, 具有较好的交互性和处理效率。如Shape文件图层的加载、图像文件的叠加、局部地形详细查看、淹没区水位、流量数据的加载与动态修改和点、面、线信息的编辑等功能。

2) 科学计算及可视化。河道、湖区水位、流量和河道等级数据的演示以及实时显现河道与湖区的中任意点的水位、高程、通航能力等信息。

3) 虚拟环境模拟。可实现基于三维模型的高分辨率图像浏览, 遥感图像分辨率最高可达到15 cm, DEM数据分辨率湖区为25 m, 湖区外为90 m; 实现分类信息图层表达, 包括自定义的河网编码、水位淹没线、地名标注等图层; 鄱阳湖区的全景、河道视点控制等功能。

2.2 地形处理

World Wind卫星数据可自动更新, 低分辨率的Blue marble数据也包含在内, 当用户放大特定区域到一定比例尺时, 附加的高分辨率数据将会自动从NASA服务器上下载, 遥感影像与SRTM高程叠加生成三维地形。SRTM高程数据的分辨率在中国范围内是90 m, 不能满足鄱阳湖水位动态变化仿真的要求, 必须将已有鄱阳湖区的高分辨率地形数据处理成World Wind地球模型能够识别的数据格式。

1) 处理SRTM数据, 生成数字高程模型(DEM), 利用ENVI软件将鄱阳湖区的SRTM数据进行镶嵌、裁剪及调整分辨率(25 m)后, 导出为TXT格式的DEM数据文件。

2) 利用ArcMap软件, 将鄱阳湖湖区及河道的高精度Shape格式等高线数据(重点地段加密测量)转换成栅格DEM数据(水平分辨率25 m)。将湖区和河道外部高程低于60 m的网格数据的高程值修改为60 m, 使得在设置动态淹没水位时水不会外流到湖区外或河道外部, 确保淹没面积计算正确。

3) 将鄱阳湖区的DEM数据、河道DEM数据与SRTM数据同步同化^{[7, 8]}, 将同步同化后的研究区DEM数据转换成带有地理投影的TIF格式图像文件。

4) 将地形数据进行瓦片切割。在鄱阳湖湖泊水位仿真中, 当视野集中在某一地区时, 动态加载该地区的地形数据, 而不是一次性将所有地形数据加载, 这就实现了不同数据来源的遥感影像、高程数据在地球模型中流畅的显示和信息提取。高程数据同纹理数据一样分层存储, 数据存放在“ \Cache\Earth\Images\NASA Landsat Imagery\NLT Landsat7(Visible Color)” 目录。从服务器下载的图像为JPG格式, 512像元× 512像元, 下载完毕后转换为DDS格式, DTX3压缩, 下载的临时文件后缀为jpg.tmp。World Wind的分层技术以地球360° 经度和180° 纬度为标准, 第一层以36° 划分, 分为(360/36)× (180/36)=50层, 第二层以18° 划分, 第三层以9° 划分, 依次类推^[4], 如图2、图3所示。

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	图2 多分辨率分层原理图Fig.2 Multiresolution layered principle

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	图3 World Wind分层结构图Fig.3 World Wind’ s layered structure

针对鄱阳湖区地形数据, 主要采用瓦片切割工具FWTools和Dstile将地形TIF格式文件切割成分级的多分辨率图像分层文件集合。创建瓦片的通用命令行格式为: dstile.exe --tile --lztsd tile_size --wwcache --overviews output_directory georeferenced_image_file(s)。其中参数如下: tile_size 为图层瓦片大小, 十进制数, 能被180整除(最好为180/2ⁿ); output_directory为瓦片金字塔的输出路径; georeferenced_image_file(s) 为影像数据的完整路径, 一系列的多重影像可以自动组合成单一的瓦片金字塔。命令说明: ①--tile, 作用是Dstile将要创建瓦片金字塔; ②--wwcache, 作用是Dstile按World Wind的内部格式组织和命名创建的瓦片; ③--overviews, 作用是Dstile去创建所有可以创建的瓦片图层。

5) 配置Earth.xml地球加载文件, 使得地球模型运行时自动加载研究区的高分辨率DEM数据。在config文件夹下找到Earth.xml, 在< TerrainAccessor> 标签下添加“ < Higher Resolution Subset> 地形数据名称, < /Higher Resolution Subset> ” 标签。名字和数据集名字要与上面自定义的文件夹名称相同。

2.3 水位仿真插件开发

World Wind提供两种扩展系统功能的方法: Plug-in(插件)机制和Add-on(附加)技术。插件机制支持多种语言的插件形式, 具有较高的运行效率。水位仿真插件是借鉴World Wind 1.4版本中的插件机制开发的, 主要设计思路如下:

1) 选取一个矩形范围的左上角和右下角经纬度, 作为水位演示区域, 即为Rect1。

2) 计算当前的取景视野矩形范围, 即为Rect2; 计算Rect1和Rect2两个矩形的交集, 即为Rect3。本步骤中采用了动态计算Rect2的方法, Rect2的mesh网格大小是128× 128。因此, 当视野距离研究区较远时, 看到的淹没范围分辨率较低; 当放大到一定倍数时, 即视野离研究地点越近时, 看到的淹没范围分辨率越高。这样做的优点是进行动态渲染时图像非常流畅, 其缺点是计算机的CPU占用率较高。

3) 对Rect3矩形区域作行数和列数为128的双层循环, 以(地球半径+水位× 垂直夸张系数)为半径构建一个网格mesh, 并可以动态设置mesh的颜色和水位, 这样当某一点的水位高于该点的高程时, 该点就被mesh网格覆盖, 呈现了湖水淹没范围特效。反之, 当某一点的水位低于该点的高程时, 该点就覆盖了mesh网格, 呈现陆地或高山景象的特效。

4) 对Rect3矩形区域作行数和列数为128的双层循环, 计算每一个小单元的水位值减去当前高程值, 然后以标签的形式输出当前点的经度、纬度、高程、水位、水深和航道级别信息。

2.4 地理空间数据扩展

1) 矢量数据。World Wind可将本地的Shape文件作为图层加载到World Wind地球模型上, 能将地理要素对应到正确的地理位置上, 并能自动显示出World Wind中的属性信息。鄱阳湖仿真系统中需要1∶ 25万水系图(河流、湖泊)、地标(详细到村镇)、公路、铁路、省界及河网编号等点、线和面的Shape文件格式数据。

2) 栅格数据。开发栅格图像叠加的功能插件, 将本机的栅格数据叠加到World Wind三维地球模型上, 并且可以调整栅格图像的透明度, 方便用户进行深入的观察分析。将不同时期的Landsat鄱阳湖地形处理成TIF格式的图片, 对高程数据及TM/ETM⁺卫星图像作前期处理时可以用使用Global Mapper软件处理, 配准加载到World Wind中实现地形变迁分析。

3) 3D模型数据。鄱阳湖的一些水工建筑物3D模型, 可以运用XML文件以静态方式加载到仿真系统中, 动态管理各个模型。使用AutoCAD建模软件, 建立水闸、船舶等三维模型, 导出为* .x格式三维模型文件, 编写XML配置文件加载本地3D模型数据到World Wind平台上显示。

3 湖泊水位仿真系统应用

3.1 鄱阳湖淹没范围仿真

鄱阳湖水位仿真系统可有效地模拟不同控制水位下的湖区及河道的淹没情况, 如图4所示。图5是在12~19 m的控制水位条件下的湖水淹没情况。

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	图4 控制水位淹没范围的叠加显示Fig.4 Superposition display of control water level and submerged range

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	图5 控制水位下的淹没范围Fig.5 Submerged range under different water level

选取栅格步长100 m的鄱阳湖区的栅格覆盖, 总栅格子数为1 490 890个(1 537行× 970列), 其中无数据总栅格数为967 368个, 有数据总栅格数为523 522个。表1是鄱阳湖区在不同控制水位状态下的水深面积的统计表; 图6是在一定的水位条件下, 不同水深的统计曲线图; 图7是淹没面积与水位关系曲线; 图8是未淹没面积与水位关系曲线图。

表1 鄱阳湖区不同水位下不同湖区内水深水域面积 Tab.1 Poyang Lake under different water submerged depth statistics

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	图6 水深2 m以下的淹没面积曲线Fig.6 Submerged area curve(depth of 2 m)

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	图7 淹没面积与水位关系曲线Fig.7 Submerged area and water level relation curves

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	图8 未淹没面积与水位关系曲线Fig.8 Unsubmerged area and water level relation curves

3.2 鄱阳湖水位的环境影响分析

1)对候鸟的影响。鄱阳湖为一过水性吞吐型湖泊, 洪水季节水位在19.0 m左右; 枯水季节(11月至次年3月)湖面萎缩, 水位一般低于10.0 m。在冬季水位下落的过程中大片滩地出露, 珍禽候鸟云集, 冬季气温适合鸟类生存。从图6中可以看出, 当水位大于16 m时, 水深为2 m以下的水域面积迅速减少。有关研究表明, 湖区水深在2 m以内是有利于候鸟的栖息的^[12], 可见, 鄱阳湖水位和水深的变化对候鸟的栖息有一定的影响。

2)对航道的影响。当环鄱阳湖区枯水期调控水位到15~16 m时, 对枢纽上游航道而言亦能形成真正意义上的环鄱阳湖千吨级(Ⅲ 级)以上标准的高等级航道网。为水运发展的需要, 建议鄱阳湖水利枢纽枯水期调控方案首选16 m, 其次可采用15 m。

3)对港口的影响。南昌港是江西省的水运枢纽港, 是由交通部定位的全国内河28个主要港口之一。环鄱阳湖区枯水期调控水位15 m以上时, 将使南昌港的深水港口岸线条件有一个质的飞跃, 与长江黄金水道枯水期维护性航道水深一致, 可实现南昌港水运货物的江海直达。综合上述枯水期调控水位方案对环境影响来看, 枯水期调控水位15 m及以上为可接受方案。

4 结论

1)基于GIS, World Wind和遥感技术, 仿真了环鄱阳湖区枯水期不同调控水位对环鄱阳湖航道通航水位、港口、岸线的影响分析, 仿真结果有利于鄱阳湖水利枢纽水位调控的决策需求。

2)系统仿真了环鄱阳湖区枯水期不同调控水位(吴淞高程分别为16 m, 15 m, 14 m和13 m)的情况, 并综合枯水期调控水位方案对航道影响, 得出枯水期控制水位15 m是对该区域的生态和通航比较有利的方案。

3)目前的湖区地形数据采用了Dstile工具处理成World Wind所需要的金字塔式的瓦片图像数据, 这对于具有时间序列的地形数据进行时态的对比分析是不利的, 需要进一步研究。

The authors have declared that no competing interests exist.

参考文献

View Option

[1]	刘小江. 超大地形三维模型设计与制作[J]. 计算机仿真, 2010, 27(1): 24-26. [本文引用:1]
[2]	潘伟, 郑逢斌, 乔保军, 等. 基于NASA World Wind的GeoTIFF影像显示方案研究[J]. 计算机应用, 2009, 29(6): 1745-1747. [本文引用:1]
[3]	World Wind Central, Open Source Community Portal, http://www.worldwindcentral.com. [本文引用:1]
[4]	Bluck J, NASA Computer Program is ‘Hot Download’ on the Internet. 2004, http://www.nasa.gov/vision/earth/environment/World_Wind.html. [本文引用:2]
[5]	刘永, 郭怀成, 周丰, 等. 湖泊水位变动对水生植被的影响机理及其调控方法[J]. 生态学报, 2006, 26(9): 3117-3126. [本文引用:2]
[6]	马庆华, 郑逢斌, 乔保军, 等. 基于World Wind矢量数据压缩的研究与实现[J]. 河南大学学报: 自然科学版, 2009(7): 403-406. [本文引用:1]
[7]	周毅, 汤国安, 王春, 等. 基于高分辨率DEM的黄土地貌正负地形自动分割技术研究[J]. 地理科学, 2010, 30(2): 261-266. [本文引用:1]
[8]	周德民, 程进强, 熊立华. 基于DEM的洪泛平原湿地数字水系提取研究[J]. 地理科学, 2008, 28(6): 776-781. [本文引用:1]
[9]	齐述华, 龚俊, 舒晓波, 等. 鄱阳湖淹没范围水深和库容的遥感研究[J]. 人民长江, 2010, 41(9): 35-38. [本文引用:1]
[10]	蒙海花, 王腊春, 黄胜晔. 鄱阳湖径流量时间序列的混沌特征分析[J]. 长江流域资源与环境, 2011, 20(5): 540-545. [本文引用:1]
[11]	王庆, 廖静娟. 基于SAR数据的鄱阳湖水体提取及变化监测研究[J]. 国土资源遥感, 2010(4): 91-97. [本文引用:1]
[12]	游文荪, 丁惠君, 许新发. 鄱阳湖水生态安全现状评价与趋势研究[J]. 长江流域资源与环境, 2009, 18(12): 1173-1180. [本文引用:1]

2010

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刘小江. 超大地形三维模型设计与制作[J]. 计算机仿真, 2010, 27(1): 24-26.

将地形信息融入作战与训练背景中,是近来各家作战实验、军事训练机构包括地方工业部门争相研究与应用的热门,其技术发展很快,方法多样,效果千差万别.文中论述一种海战场地理信息快速建模和仿真方法,从初期数据收集、中期的数据处理、合成、到后期显示驱动,实现了超大地形的三维显示. Abstract： Integrating topographic information into operation and training background is becoming more popular in the recent research and application of various battle experiments and military training institutions, including local in-dustry sectors. Its technology has developed rapidly, the methods and their results axe varying. In this paper, a naval battle geographic information fast modeling and simulation method is introduced, from ini-tial data collection, medium-term data processing and synthesis, to the latter part of display driver, to achieve a large three-dimensional terrain display.

... 国内外学者对大地形建模和仿真技术做了大量的研究,综合运用了地形多分辨率表示法、层次细节载入LOD(level of detail)控制和地形生成算法等^[1,2] ...

2009

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潘伟, 郑逢斌, 乔保军, 等. 基于NASA World Wind的GeoTIFF影像显示方案研究[J]. 计算机应用, 2009, 29(6): 1745-1747.

鏊于遥感影像GeoTIFF研究过程中对地理信息的需求,提出了基于World Wind的GeoTIFF显示方案.在对World Wind分层显示进行深入研究的基础上,采用添加Geo TIFF图层的方式显示影像数据和设置影像alpha值的方式透视影像覆盖区域的地表特征.实验证明该方案能够快速地显示GeoTIFF影像,能方便地查看GeoTIFF覆盖区域的地表特征.

... 国内外学者对大地形建模和仿真技术做了大量的研究,综合运用了地形多分辨率表示法、层次细节载入LOD(level of detail)控制和地形生成算法等^[1,2] ...

0.0

... World Wind是一款由NASA开发的三维地理信息系统,该系统利用Landsat 7,SRTM,MODIS等多种卫星遥感数据,将卫星图像与SRTM数字高程模型叠加在一起,实现三维地球仿真^[3,4] ...

2004

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... 划分,依次类推^[4],如图2、图3所示 ...

2006

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刘永, 郭怀成, 周丰, 等. 湖泊水位变动对水生植被的影响机理及其调控方法[J]. 生态学报, 2006, 26(9): 3117-3126.

This paper analyzes the impact of lake water level fluctuation on aquatic ecological systems based upon studies documented in a wide range of literatures throughout the world. Lake water level fluctuation (LWLF) plays a significant role in ecological restoration and ecosystem management. The impact of LWLF on aquatic ecological systems has been widely studied in recent years, with some of the more recent studies focused on the relationship between LWLF and aquatic vegetations, particularly submerged plants. It is important to maintain an ecologically suitable water level to sustain a healthy lake ecosystem. An ecologically suitable water level is in general characterized by the magnitude, frequency, timing and duration of water level fluctuation. As suggested by many studies, LWLF impacts aquatic ecosystems in both direct and indirect ways, and at various scales from the very small to the ecosystem level scales. LWLF demonstrates different patterns, including short- and long-term LWLF, as well as long-term high and low water levels. Winds and waves are the dominant factors causing short -term LWLF with associated increase in total suspended solid (TSS) concentration and light extinction, which would leads to changes in aquatic and near shore vegetations. Seasonal and long-time LWLF is responsible for more significant changes in lake ecosystems. Long-term high and low water levels, and some abnormal changes in water levels can cause low species diversity or declined biomass. It is considered an important management tool for shallow lake restoration to integrate the role of LWLF into the water-level management framework. The maximum bio-suitable water depth and species diversity index are taken as indictors for water level control. The magnitude, frequency, timing and duration of LWLF need to be adjusted for lake restoration. The main study methods, including statistical analysis of long-time historical data, ecological modelling approach and reference lake approach, are proposed in recent studies. The basic water level control measures include: (1) reducing frequency of flow variation; (2) increasing seasonal variation and avoid extreme conditions; (3) reintroducing seasonal flow peaks; (4) increasing seasonal high flows; (5) reducing high flows, especially those badly timed; and (6) reducing intensity of water-level change. Several limitations in the past studies on this topic are identified as: (1) absence of studies on the effects of LWLF on overall aquatic ecosystems; (2) lack of comprehensive ecological modeling studies to quantify the impact of LWLF; (3) lack of sufficient attention to the role of water level control in lake management; and (4) lack of studies on the effects of global warming on LWLF and lake ecosystem. Based on the intensive literature review, this paper presents some potential research directions and methods for water level control and lake ecosystem response.

水位的高低及其变动范围、频率、发生的时间、持续的时长和规律性等是影响湖泊水生植被的核心因子。水位变动有短期、年内季节性和年际变动3种，对湖泊水生植被有不同的影响机理。水位短期变动通过对水体中的悬浮物、透明度、光衰减系数等的影响而对水生植被产生作用；周期性的年内季节性和年际水位变动可对水生植被的生态适宜性产生影响，并进而改变其时空分布；长期的高水位和低水位以及非周期性的水位季节变动会破坏水生植被长期以来对水位周期性变化所产生的适应性，从而影响了植被的正常生长、繁衍和演替。植被的极端深度和物种多样性是水位调控的核心表征指标，可通过经验数据分析法、生态模型法和参照法等方法来确定湖泊的适宜水位变动范围和时间。研究对象选择、研究方法、管理中的应用以及重要环境变化所产生的影响等是今后相关研究的核心问题。

... World Wind是采用C#语言编写的开源软件,研究人员能够自由修改源代码,扩展其功能和样式,在科学、教育和政府等行业应用中都有非常大的潜力^[5] ...

... 湖泊的水文过程决定了湖泊生态系统的结构和功能,水位变动是影响湖泊生态系统状态长期变化的最主要因素^[5] ...

0.0

马庆华, 郑逢斌, 乔保军, 等. 基于World Wind矢量数据压缩的研究与实现[J]. 河南大学学报: 自然科学版, 2009(7): 403-406.

矢量数据的压缩对于数据网络传输以及提高整个可视化系统的效率来说是一项很莺要的工作.本文对现有曲线矢量数据压缩算法进行比较,着重分析了曲线矢量数据压缩的Douglas-Peucker算法及相关理论,给出了该算法的递归实现,并在World Wind环境中实现了Shape格式文件的快速显示.实验结果证明,经过压缩后的矢量数据兼顾存储空间和显示精度,提高了World Wind应用效率.

2010

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周毅, 汤国安, 王春, 等. 基于高分辨率DEM的黄土地貌正负地形自动分割技术研究[J]. 地理科学, 2010, 30(2): 261-266.

China Loess Plateau is world-wide famous for its peculiar and unique landscape, in which the loess shoulder-lines zigzag on the surface making a distinct separation between loess positive terrain and the negative one. The automatic segmentation of loess positive and negative terrains (P-N terrains)with precise location and high efficiency, which is a crucial technique in constructing the mechanism-process models of loess landform drainage systems, is still need to be further improved. Nowadays, with the increasing availability of digital topographic data, the Digital Elevation Model (DEM)can now be applied to better description of natural topography, and it is also regarded as the most proper data source for automatic extraction of loess positive and negative terrains. In this paper, the conformation and flow confluence characteristic of the hill-slope in representative loess landforms is discussed. Based on this, an auto-segmentation method of P-N terrains from 5 m resolution DEMs is proposed. There are three key procedures in the operation. The first step is the identification of grid points on the shoulder-line position by considering the slope difference up and down. Slope gradient 30°,25°and 20°are used as the thresholds in loess platform area, loess ridge-hill area and loess hill area respectively in the extraction model. The second stage is to expand shoulder-lines’candidate cells directionally by considering the spatial direction of the local hill slope aspect and the trend of the shoulder-lines. This step is helpful for deriving more consecutive and detailed shoulder-lines on DEMs. The third step is the generation of positive terrain which can be regarded as the extraction of the upstream area of the shoulder-line points by using the hydrologic analysis model. All the shoulder-lines’cells derived above are imported into the model as the pour point data. This is an alternative method for evading the difficulty of converting shoulder-line grid cells into consecutive vector lines. Validation tests are took out by contrasting the auto-extraction results from DEMs and the delineating results from 1 m resolution DOMs in six drainages. Results show that maximum area difference between the positive terrain area derived above and actural area is 1.15 km 2 , and the percentage of the cells distance offset values less than 10 m exceed 95%. So the main advantages of this approach are high accuracy, lower demands on manual intervention and ready availability of required data for many regions on the Loess Plateau. The morphology of the earth surface is the interactional production of the hydrosphere, lithosphere, atmosphere and the biosphere, thus the morphology is the external representation, and the interaction process is the inner dynamical force. The extraction of the topographic feature lines not only need considering the characteristic of the terrain morphology, but also need considering the inner mechanism of land surface process.

黄土地貌正负地形自动分割是构建地表空间分布式机理-过程模型的基础。在分析黄土高原地区典型地貌坡面形态及汇流过程特征的基础上,提出了基于5m分辨率栅格DEM自动分割黄土正、负地形的技术方案。该方案首先利用坡面上下游栅格点的坡度对比识别沟沿线点,然后利用汇水模型提取沟沿线点约束的上游汇水区域,从而实现正、负地形的自动分割。在黄土塬区及丘陵沟壑区的实验结果表明,该方法的优点是提取精度高,人工干预少,在不同地貌类型区域内有很好的应用适宜性。

... 3) 将鄱阳湖区的DEM数据、河道DEM数据与SRTM数据同步同化^[7,8],将同步同化后的研究区DEM数据转换成带有地理投影的TIF格式图像文件 ...

2008

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周德民, 程进强, 熊立华. 基于DEM的洪泛平原湿地数字水系提取研究[J]. 地理科学, 2008, 28(6): 776-781.

For study of digital surface hydrological elements controlled by DEM in the wetland area of Sanjiang Plain, Northeast China,both the ArcGIS9.0 Hydro Arc Tools module and the module based on the modified Breaching and Flat Area Algorithm are used to extract the hydrological elements from the DEM data at scale of 1:10000. With the digital method, the study area is delineated into 6 catchments, 82 ponds and depressed low-lying as well as a drainage net-work of both Woyalan River and Nongjiang River. The research indicates that the digital hydrological elements can be extracted successfully from high precise DEM, however, it need to be modified for many times before and after automatic digital extraction due to the problems of digital riverways’ excursion and distortion. For improving both precise and efficiency of digital extraction in the wetland area of a flood plain, some key issues need to be carried out such as development of efficient Algorithms professionally for flat areas and an efficient pretreatment on DEM without loss of key hydrological information.

为了研究探索洪泛平原湿地区域基于DEM的地表水要素数字特征,采用ArcGIS9.0的Hydro Arc Tools模块,配合改进升值裂开算法编制的程序在三江平原洪河保护区1:1万比例尺的DEM基础上进行了数字水系提取研究,将研究区划分为6个数字集水区,提取出以沃绿兰河-浓江河为主的数字河网,以及大小82处泡沼和洼地。研究表明,在保持高精度DEM前提下,数字地表水系统可以通过基于DEM自动提取出来,但是存在河道偏移以及河网形态失真等问题,需要在进行数字提取前后进行多次修正。在DEM数字高程预处理过程中保持高程信息的水文特征不丢失,以及发展专业处理平坦区域和低洼地域的有效算法,将是进一步提高洪泛平原湿地区域数字水系提取效率和精度的关键。

... 3) 将鄱阳湖区的DEM数据、河道DEM数据与SRTM数据同步同化^[7,8],将同步同化后的研究区DEM数据转换成带有地理投影的TIF格式图像文件 ...

2010

0.0

... 水位和水域面积的变化造成鄱阳湖天然湿地各类型之间的动态变化^[9] ...

2011

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蒙海花, 王腊春, 黄胜晔. 鄱阳湖径流量时间序列的混沌特征分析[J]. 长江流域资源与环境, 2011, 20(5): 540-545.

In the paper,the chaotic characteristics of hydrological time series from the stations which entering into Poyang lake basin were analyzed.In order to make full use of the abundant evolvement information contained in the monthly runoff series from 1955~2001 on Waizhou,Lijiadu and Dufengkeng stations,the method of CC was used to select the lag time 〖WTBX〗τ〖WTBZ〗 and the phase space of dimensions 〖WTBX〗m〖WTBZ〗.The main quantitative indices such as saturated correlation dimension and the maximum Lyapunov exponent of the monthly runoff series,which could be taken as the chaos features of the hydrology system,were calculated.The saturated correlation dimension was estimated by GP method，and maximal Lyapuonv exponent was calculated by Rosenstein method.The calculated results indicated that monthly runoff time series of the Waizhou,Lijiadu and Dufengkeng stations were all nonintegers.At the same time,the maximum Lyapunov exponents gained from the datum were all positive numbers,which sufficiently showed that the runoff system of Waizhou,Lijiadu and Dufengkeng stations had fractal characteristics and chaotic characteristics.The saturated correlation dimension and the maximum Lyapunov exponent of the monthly runoff series showed that the monthly runoff series was most complex at Waizhou station,the Lijiadu station was secondary,and the Dufenkeng station was least complex.

流域径流受诸多因素影响，变化复杂，仅凭观测站统计数据难以发现其演变规律。以混沌理论为基础，以鄱阳湖入湖外洲站、李家渡站和渡峰坑站的月径流时间序列为研究对象详细说明了求取时间序列中混沌特征数的方法。首先利用CC方法选取相空间重构参数即时间延迟〖WTBX〗τ和嵌入维数m〖WTBZ〗，在此基础上进行相空间重构，采用GP关联积分法计算关联维数和Rosenstein小数据量法计算最大Lypanuov指数。结果表明鄱阳湖入湖外洲站、李家渡站和渡峰坑站的月径流序列的饱和关联维数非整数，同时最大Lyapunov指数也为正数，这充分说明鄱阳湖入湖外洲站、李家渡站和渡峰坑站的月径流序列均具有明显的混沌特征。而且通过最大Lyapunov指数和关联维数的计算表明鄱阳湖入湖的外洲站月径流复杂程度最大，混沌特性最强，对初值的敏感性最强，李家渡站次之，渡峰坑站最小

... 南昌是江西省的省会,而南昌港则是江西省的枢纽港,在全省处于航运中心的地位^[10,11],鄱阳湖水利枢纽工程对南昌港港口岸线资源影响主要取决于鄱阳湖区水位的控制情况,鄱阳湖地区的水系及城镇分布情况如图1所示 ...

0.0

王庆, 廖静娟. 基于SAR数据的鄱阳湖水体提取及变化监测研究[J]. 国土资源遥感, 2010(4): 91-97.

In order to extract the open water from the Poyang Lake by applying SAR data in different periods, the authors firstly analyzed the scattering mechanism of water，vegetation and sand，then used the texture of SAR imagery and polarized ratio and polarized difference to enhance the description of targets, and employed principal component transformation to enhance the contrast of water and other objects. With the first component，the area of open water on SAR imagery could be effectively and accurately extracted by setting up a proper threshold. The SAR images used were Envisat-ASAR and ALOS-PALSAR alternating polarization mode data. Meanwhile，after the analysis of two kinds of sample data with Jeffries-Matusita distance，ASAR data with C band could provide more accurate extraction of open water than those of PALSAR with L band. Finally，the open water of the Poyang Lake was extracted from SAR imagery in spring，summer and winter，and the changes of water area indicated the regular change of the open water of the Poyang Lake.

以C波段Envisat ASAR和L波段ALOS PALSAR交替极化模式的数据为数据源，分析了鄱阳湖主要地物的散射特性，并分别引入纹理特征和不同极化通道间的极化差和极化比等参数增强地物的表征；应用主成分变换对地物的参数向量进行特征提取，增强水体与其他地物的差异，并在第一主成分中选择适当阈值，准确提取出不同时期的鄱阳湖水体信息。实验表明，用上述方法提取水体信息的精度比直接使用地物后向散射系数的监督分类法提取精度要高得多。通过分析和对比上述不同波段SAR数据中水体与其他类别间的Jeffries-Matusita距离可以看出，C波段SAR数据提取鄱阳湖水体的精度比L波段高。并给出了鄱阳湖水体在2007年春、夏和冬3个季节中水域面积的动态变化情况。

2009

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游文荪, 丁惠君, 许新发. 鄱阳湖水生态安全现状评价与趋势研究[J]. 长江流域资源与环境, 2009, 18(12): 1173-1180.

In this paper，the grade of water ecosystem security in Poyang Lake was confirmed by analyzing social economical and water ecological information，using PressureStateResponse (PSR) model，AHP and Composite index methods.Results showed that the indicators such as sanitary sewage processing rate，chemical fertilizer quantity，million GDP water consumption，water quality in Poyang Lake and 〖WTBX〗Oncomelania acreage，etc，had considerable influence on water ecosystem in Poyang Lake.The water ecosystem security value in Poyang Lake in 2005 was 0513 3，which meant “basically safe”.And the value would be 0565 1 in 2010 according to the prediction，higher than that in 2005 but still belonged to “basically safe”.In the near future，the water ecosystem security value in Poyang Lake would fluctuate within “basically safe”.With the social economical development of the lake surrounding area and the increasing environmental pressure，the changing trend of water ecosystem security in Poyang Lake would not be optimistic if the protection efforts are maintained at the present level.Lack of response measures to environmental pressure and deficiency of active awareness and action to protect water ecosystem are the main reasons that lead to the low security grade in Poyang Lake.

通过收集整理鄱阳湖社会经济、生态环境和水环境资料，运用PSR模型、层次分析法和综合指数法确定鄱阳湖现状年的水生态安全度并预测鄱阳湖水生态安全发展趋势。结果表明：城镇生活污水处理率、农业化肥施用量、万元GDP用水量、鄱阳湖水质、钉螺面积等指标对鄱阳湖水生态安全有较大影响；鄱阳湖现状（2005年）水生态安全度为0.513 3，属于“基本安全”；2010年鄱阳湖水生态安全度为0.565 1，较2005年有所提升，但仍属于“基本安全”的范畴；近期内，鄱阳湖水生态安全度将在“基本安全”的范畴内波动。随着湖区周边经济社会的发展，环境压力的不断加大，若维持现有的保护力度，则鄱阳湖水生态安全的变化趋势不容乐观。应对环境压力的响应措施不足，主动保护水生态系统的行为或意识较为欠缺，是导致鄱阳湖水生态安全等级不高的主要原因。

... 有关研究表明,湖区水深在2 m以内是有利于候鸟的栖息的^[12],可见,鄱阳湖水位和水深的变化对候鸟的栖息有一定的影响 ...