星载激光雷达在青藏高原湖泊变迁中的应用研究

基于ICESat GLAS数据,结合气温和降水地面观测数据,利用ANUSPLINE空间内插法和Theil-Sen’s中值斜率法,分析探讨HY 2003~2010年青藏高原湖泊水位变化特点及其对气候变化的时空响应特征。结果表明:青藏高原大部分湖泊水位集中在4 500~5 000m,主要分布在青藏高原的中部和西部地区,该地区湖泊水位变化十分剧烈,部分湖泊水位上升十分明显。高原南部的打加错、羊卓雍错和高原西部的班公错的湖泊水位下降趋势显著。同时,不同流域的湖泊水位随着气温和降水的变化而呈现出不同的变化趋势,湖泊水量的增加除依靠降水的直接补给外,也会受由温度变暖引起的积雪融水增加的影响。     

青藏高原湖泊现代变化遥感方法研究

我国青藏高原分布着地球上海拔最高、数量最多、面积最大的高原湖群。据统计, 仅青藏高原面积大于1. 0 km ² 的湖泊就有1 091 个, 总面积约44 993. 3 km², 约占全国湖泊总面积的49. 4%。青藏高原湖泊不仅是青藏高原水循环的一个关键因子, 也是青藏高原生态环境的重要要素, 青藏高原湖泊的变化是气候变化敏感的指示器。在全球气候变暖的影响下, 对气候反应敏感的冰川和冻土都在退缩和融化, 青藏高原的湖泊也有明显的响应。青藏高原自然条件恶劣, 交通不便, 数据采集困难。卫星遥感技术是探测湖泊的先进手段, 随着遥感资料的日益丰富, 应用遥感手段研究湖泊变化是可取的方法。1970～2000 年以来的地形图、航空相片和多时相TM 卫星遥感资料, 建立湖泊现代变化遥感综合分析方法, 并对青藏高原南部的羊卓雍湖和沉错等湖泊的变化进行了分析。结果表明, 用遥感方法研究湖泊变化是可行的; 在1970～2000 年期间, 地处青藏高原南部的羊卓雍湖和沉错湖都呈萎缩趋势, 但在1990～2000 年期间有微弱的扩大趋势。     

ICESat-1/GLAS数据湖泊水位监测研究进展

湖泊水位动态监测和调查对湖泊资源利用、水循环过程和生态环境变化等研究具有重要意义。ICESat-1/GLAS激光测高数据已经在全球陆地、森林植被和极地冰盖变化监测等方面得到了广泛应用,但在湖泊、河流等内陆水体监测方面的应用研究相对较少。本研究系统分析了国内外利用GLAS数据,以及GLAS和其他卫星测高数据、光学遥感数据联合反演湖泊物理参数方面的研究进展,探讨了该数据在湖泊应用中的关键技术和难点,如GLAS数据的精度评价、湖泊脚印点自动提取等,分析了目前研究中存在的问题,以期对我国即将发射的高分七号测绘卫星在水文方面的应用提供参考。     

可可西里湖泊水面面积与雪冰覆盖率相关分析

气候变化对青藏高原湖泊水面面积会产生很大的影响,雪冰覆盖作为气候变化的一个重要因素,也对青藏高原湖泊水面面积有一定的影响。利用遥感影像提取2009—2017年可可西里地区库塞湖及周边四湖(简称为四湖)的年水面面积,同时,利用2005—2016年的MODIS积雪产品,提取四湖集水区雪冰覆盖率,结合同期五道梁气象站点的逐月平均气温数据和降水量,对四湖水面面积变化与集水区雪冰覆盖变化规律及其与五道梁站气温与降水量之间的关系进行探讨。分析表明:1)卓乃湖2011年9月溃决后,4个湖泊的水面面积都发生较大的改变;2)2005—2014年期间,四湖集水区雪冰覆盖率总体呈小幅度增加趋势;3)卓乃湖溃决后,库塞湖及卓乃湖的水面面积与五道梁站年均气温的相关性显著提高,而库塞湖及卓乃湖的水面面积与四湖集水区雪冰覆盖率的相关性显著降低。     

基于GSM的水位与降雨量在线监测系统

本文设计的基于GSM水位与降雨量在线监测系统,是通过现有的GSM网络,利用短消息方式,进行单片机和TC35模块开发的远程数据采集;实现了远距离采集数据与GSM无线数据传输技术相结合,完成江河、湖泊及水库等水位和该区域降雨量的远程在线监测,摆脱有线困扰,能够实现水文站的无人值守功能.     

基于遥感的西藏S301公路沿线湖泊变化研究

西藏S301公路联结那曲和阿里地区,东接青藏铁路、G109线青藏公路及G317线川藏北线,西接G219线新藏公路,是西藏“三纵、两横、六个通道”骨架公路网中的北横线西段,是通往阿里地区的重要通道之一,其路网地位和作用十分重要。该公路经过地区湖泊纵横,在全球气候变暖、冰川融化退缩和冻土退化的背景下,湖泊水位上涨给公路带来许多隐患。利用1970~2000年来的地形图、航空相片和多时相TM卫星遥感资料对西藏S301公路沿线的湖泊变化进行了遥感综合分析,并对湖泊变化对公路的影响进行了研究。结果表明,在1970~2000年期间,西藏301公路沿线的湖泊以扩张为主,部分湖泊的水位上升对西藏301公路已造成较大影响,此公路的改扩建工程一定要考虑公路沿线湖泊水位上升所带来的影响。     

青藏高原地区湖泊面积插补迭代自动提取

青藏高原湖泊面积变化在反映气候变化方面具有非常重要的意义。通常的阈值法提取湖泊面积由于受到冻湖、山体阴影和冰雪的影响,进行大范围提取时会存在阈值选择的不确定性和较难实现自动化提取等问题。基于归一化差异水体指数NDWI(Normalized Difference Water Index)、数字高程数据和雪盖指数NDSI(Normalized Difference Snow Index),提出了针对冻湖的湖泊面积插补迭代自动提取方法。结果表明,此方法能够实现非冻湖和冻湖阈值的自动确定,不仅可以在大范围内准确地完成湖泊面积提取,而且能减少山体阴影、冰雪的干扰。该方法相较于传统的基于水体指数的阈值法,具有更高的分类精度。     

浅水型湖泊湿地景观季节变化分析

为阐明水位和植被生长状况的季节变化对湖泊湿地景观格局所产生的影响,以浅水通江湖泊安徽菜子湖为例,选取相邻年份不同月份的SPOT-5影像,基于RS/GIS解译得到湖泊湿地景观图,统计分析不同季节的湿地景观结构及其相互转化,并利用Fragstats景观格局分析软件从景观和类型2个层次探讨不同季节的湿地景观格局指数变化。结果表明,菜子湖湿地景观以水体为主,受到湖泊水位和植被生长状况影响,湿地景观结构发生明显的季节变化;湖泊湿地景观的季节变化是以不同类型之间的可逆转移实现的;随着湿地景观结构的改变,类型和景观2个层次的景观格局指数也发生季节性波动。该研究可为长时间序列浅水型湖泊湿地景观变化研究中的遥感影像选取提供科学依据。     

单片机控制的水位与降雨量监测系统

为解决防洪中水位和降雨量人工监测存在的操作不安全、数据不准确和实时性不强等问题，我们开发了单片机控制的水位与降雨量监测系统，该系统以单片机为控制核心，采用了较好的系统软件与硬件，利用该系统，可实现江河、湖泊与水库水位及降雨量信息的自动采集和处理。     

基于MODIS的青藏高原雪线高度遥感监测

雪线作为区分积雪覆盖区与无雪区的边界线,是冰冻圈各要素中对气候变化最为敏感的指示器。利用去云后的MODIS积雪面积比例产品并结合DEM数据,通过雪线像元及其高度的提取、雪线高度场的建立,对青藏高原近12a(2000~2011年)雪线高度的时空变化特征进行了分析。结果表明:青藏高原雪线高度的分布受地形的影响,高原内部的雪线高度明显高于周围山区;在近12a中,青藏高原的雪线高度变化虽然没有明显的年际变化趋势(升高或者降低),但是体现出较高的年内和年际波动特征,特别是青藏高原的东部和南部地区由于受西南季风的影响,夏季雪线高度的年际变化尤为强烈。提出基于MODIS的雪线高度提取方法具有较好的应用潜力,能够适用于其他地方雪线高度的遥感监测。     

New method and error analysis of lake retrieval with MetOp-A AVHRR images on the Tibetan Plateau

Land-surface water is an important factor influencing the regional environment and climate and is a key factor in the Tibetan Plateau, which is one of the most sensitive regions to global changes. Because of the high elevation, complex topography, and erratic weather of the Tibetan Plateau, direct measurement of the area of every lake is largely unfeasible. Moreover, complex natural geographic conditions increase the difficulty of image processing and information extraction with remote sensing because they enhance the uncertainty of quantitative data retrieved with satellites. Methods based on spectral features do not generate the expected results of lake area over the Tibetan Plateau due to a lack of distinction between water and other land objects, especially snow, vegetation, and low cloud cover. Therefore, a new method to extract lake area from satellite images in the Tibetan Plateau is needed. In this article, an automatic method was proposed to evaluate lake area during the wet season (from 1 September to 31 October) on the Tibetan Plateau with multi-day Advanced Very High Resolution Radiometer (AVHRR) remote-sensing images on board the Meteorological Operational satellite-A (MetOp-A) satellite. The method considers both spectral and textural features of lakes and does not need a cloud mask as an input. In addition, the Mixture Tuned Matched Filtering (MTMF) algorithm was applied to decompose the mixed pixels to better identify lakes and estimate the lake area. Based on daily lake identifications, the wet season’s lake data were composited with the maximum value composition (MVC) method to determine the lake area. A comparison of our work with the manually interpreted results from Landsat Thematic Mapper (TM) images and observational reports demonstrates the accuracy and reliability of our approach. However, certain factors, i.e. the sensor zenith angle of the polar-orbit satellite and the topography, can affect the lake area extracted from the remote-sensing images.     

Monitoring lake level changes on the Tibetan Plateau using ICESat altimetry data (2003-2009)

In this study, ICESat altimetry data are used to provide precise lake elevations of the Tibetan Plateau (TP) during the period of 2003-2009. Among the 261 lakes examined ICESat data are available on 111 lakes: 74 lakes with ICESat footprints for 4-7 years and 37 lakes with footprints for 1-3 years. This is the first time that precise lake elevation data are provided for the 111 lakes. Those ICESat elevation data can be used as baselines for future changes in lake levels as well as for changes during the 2003-2009 period. It is found that in the 74 lakes (56 salt lakes) examined, 62 (i.e. 84%) of all lakes and 50 (i.e. 89%) of the salt lakes show tendency of lake level increase. The mean lake water level increase rate is 0.23 m/year for the 56 salt lakes and 0.27 m/year for the 50 salt lakes of water level increase. The largest lake level increase rate (0.80 m/year) found in this study is the lake Cedo Caka. The 74 lakes are grouped into four subareas based on geographical locations and change tendencies in lake levels. Three of the four subareas show increased lake levels. The mean lake level change rates for subareas I, II, III, IV, and the entire TP are 0.12, 0.26, 0.19, −0.11, and 0.2 m/year, respectively. These recent increases in lake level, particularly for a high percentage of salt lakes, supports accelerated glacier melting due to global warming as the most likely cause.     

Water level fluctuations derived from ENVISAT Radar Altimeter (RA-2) and in-situ measurements in a subtropical waterbody: Lake Izabal (Guatemala)

The use of remote sensing techniques in monitoring inland waters has become a powerful tool, considering the amount of ungauged waterbodies all over the world. The water mass balance is an essential subject to take into account in water management activities. The level changes of a lake surface are an indicator of the water mass balance of a basin since they reflect the water storage variations. Space borne altimeters have been successfully used in the last decade to measure lakes, rivers and wetland stages. This study presents the first analysis of Lake Izabal — the biggest lake of Guatemala (Central America) — water level fluctuations using altimetry data and in-situ measurements. Water level variations were obtained from Envisat Radar Altimeter (RA-2) Geophysical Data Records coupled with in-situ measurements. The analysis period included three complete years (2004 to 2006). The rainfall and temperature records over the catchment were analyzed considering that the amount of water feeding the lake, either by the tributaries and/or the groundwater, is driven by the climatic conditions over the lake's catchment. The results obtained show a good agreement between both, altimeter and in-situ datasets (correlation coefficient: 0.83 and rms error: 0.09 m). Lake Izabal water level fluctuations have a seasonal signal forced by the rainy and dry climate seasons in the region. An abrupt lake level rise was found in July 2006 which is correlated to abnormal precipitations in June. We found a connection between the higher/lower extreme values in the lake level variations with rainfall anomalies produced by regional climate changes forced by El Niño Southern Oscillation and the Tropical North Atlantic anomaly.     

A Review of Lake Dynamic Change Researchbased on Remote Sensing

The shrink and expansion of lakes can reflect the regional changes in climate and environment. It has an important significance for further research of the climate change and the sustainable development.The rapid development of remote sensing technology has provided technical support for the dynamic change to real-time monitoring of lakes.This paper discussed the selection of data source,the delineation of lake water,the lake variation trends and causes.Then made a systematic summary of the current situation and progress in the studies on lake change and predicted the trends of lake change research in the future.     

Research on Lake Variation in Tibetan Plateau based on Space-borne Laser Radar

Based on ICESat data and temperature and precipitation from 2003 to 2010 and used ANUSPLINE interpolation method and Theil\|Sen’s method,we analyzed and discussed lake water level change characteristic from 2003 to 2010,as well as the temporal\|spatial response of lake water level to climate changes.the results showed that most of lakes mainly distribute in the central and western region of TP,and their lake water levels are mainly between 4 500 to 5 000 meters.Lake water level of Tak kyel and Yamzhog Yumco in the southern of TP as well as Panggong in the western of TP showed a decreasing trend.Analysis of the relationship between lake water level and climate factor indicated that lake water level in different basin showed different trends because of varied temperature and precipitation.the increasing trend of lake volume was not only dependent on direct supply of precipitation,but also effected by melted water from glaciers and snow due to climate warming.     

基于遥感的湖泊水域动态变化监测研究进展

湖泊动态变化作为人类面临的三大湖泊环境问题之一,成为湖泊研究的重点。遥感技术作为科学、快速、大面积的调查监测手段,在湖泊动态变化研究中应用广泛。从湖泊动态变化研究的基本原理和数据源、湖泊信息提取方法和遥感动态监测方法等几方面介绍了国内外遥感技术在湖泊动态变化研究的主要进展情况,并深入分析了各种数据源和分析方法的优缺点,同时讨论了当前湖泊遥感动态变化研究中存在的一些问题和发展的趋势。     

遥感湖泊面积MTMF提取方法及空间尺度效应研究

主要研究遥感湖泊面积亚像元分解提取方法和空间尺度效应,为遥感湖泊面积提取、检验及基于此的局地气候变化分析提供科学的基础数据。在对TM遥感数据进行升尺度处理的基础上,采用混合调制匹配滤波(Mixture Tuned Matched Filtering,MTMF)进行亚像元分解,得到不同空间分辨率的湖泊面积。进而分析不同面积湖泊随遥感空间尺度的变化。结果表明:(1)当通过对高空间分辨率的遥感数据重采样获取多尺度遥感影像进行湖泊面积提取及湖泊空间尺度效应分析时,采用最近邻法比像元聚合重采样法更合理。(2)MTMF亚像元分解法可以用于基于水体光谱特征的遥感湖泊边界提取和面积计算,但边界提取过程中容易将湖泊与河流或其他非湖泊的水体混淆。(3)遥感湖泊面积的提取结果受所用遥感影像空间分辨率的影响较大,影像的空间分辨率越低,湖泊面积提取的偏差越大,尤其对面积较小的湖泊。