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521.
辽东湾是典型的复杂二类水体,我们利用2002~2004年在辽东湾现场实测的叶绿素a数据(分光法、荧光法和HPLC法),以及水面之上法现场实测的离水辐射率和遥感反射率数据模拟的MODIS各相应波段值对MODIS海洋水色算法进行了评估.评估的MODIS生物光学算法有四个,即CZCS_pigm、chlor_MODIS、chlor_a_2和chlor_a_3算法.结果表明,两个一类水体生物光学算法(CZCS_pigm和chlor_MODIS)反演值与分光法和荧光法测试分析结果相比,算法均低估了叶绿素a浓度,与HPLC分析结果相比算法高估了叶绿素a浓度;两个二类水体算法(chlor_a_2和chlor_a_3)与所有叶绿素a分析方法相比,均高估了叶绿素a浓度.根据MODIS生物光学算法在辽东湾的具体表现,我们认为HPLC法分析的叶绿素a浓度更适合于作为海洋水色算法评估的现场检验依据.叶绿素a浓度的反演值和实测值之间较低的相关系数则显示MODIS两个一类水体算法所采用的波段比值不适合本海区. 相似文献
522.
为加强环境自动监测系统的建设,提供了一个支持多种类型现场信息宽接入的信息采集、支持有线和无线信息传输的开放式在线数据采集传输装置.装置用标准化的工控机作为控制核心,具备模拟信号、LonWorks信号、视频信号、RS-485信号输入接口,网络通信和GPRS远程通信方式,采用Windows操作系统和数据库技术,应用方便灵活,有助于提供有效、客观的现场环境信息,实现环境自动监测与管理. 相似文献
523.
综合考虑植被、温度和降水的四川省月尺度伏旱遥感监测 总被引:2,自引:0,他引:2
基于四川农业大省的重要性、伏旱监测的必要性、复杂地貌背景区实测气象站点的有限性以及多云雾天气下高频伏旱遥感监测的困难性,综合降水(TRM)、植被(VCI)和地表热力状况(TCI)在旱情发生发展中的作用及体现,构建基于三者加权的伏旱遥感监测模型,并完成了2000—2015年7—8月四川省月尺度伏旱监测,从伏旱多年平均状态、演变趋势、频率三方面分析了四川省月尺度伏旱的时空演变规律。结果表明:1)SDCI(归一化旱情综合指数)=0.25×VCI+0.5×TRM+0.25×TCI模型是最适用于四川省的月尺度伏旱监测模型。该模型体现了在伏旱监测过程中考虑并突出降水的重要性。2)四川省7月平均旱情强度较强,8月旱情强度整体上有所减弱;各地貌类型区7、8月旱情强度则表现为川东盆地旱情强度最强,高原与盆地过渡区次之,川西高原最弱。3)四川省整体上7月伏旱呈减缓变化,8月旱情呈加重变化。川东盆地7月伏旱以加重变化为主,8月则为减缓变化;高原与盆地过渡区及川西高原7月伏旱以减缓变化为主,8月多表现为加重变化。4)四川省不同地貌背景区伏旱频率分布特征表现为川东盆地历年旱情发生频率最高,其次是高原与盆地过渡区、川西高原。川东盆地和高原与盆地过渡区以中度干旱较为频发,川西高原则多为轻度干旱。 相似文献
524.
Detection of Coastal Saline Land Uses with Multi-Temporal Landsat Images in Shangyu City,China 总被引:11,自引:0,他引:11
Many coastal regions in China are confronted with pressing problems of scarce land resources and heavy population. Over the
past 30 years, considerable parts of coastal tidelands have been enclosed and reclaimed for agricultural land uses. To assess,
plan, and implement large-scale reclamation programs, up-to-date and reliable information concerning the nature, areal extent,
and physical and chemical characteristics of coastal saline lands is essential. This paper reports a remote sensing approach
to detecting coastal saline land uses in Shangyu City, China, by using multi-temporal Landsat images. First, with the aid
of resolution-sharpened Landsat-7 ETM+ images and their enhanced linear features, a visual interpretation is applied to extract
individual dikes. Based on time series images and local government records, a spatial zoning procedure is then used to define
six sub-zones with different historical years of reclamation. It shows that a total of 15,668 ha of coastal saline lands were
enclosed and reclaimed from 1969 to 1996. Second, a modified land-use classification system for the study area is prescribed,
and both unsupervised and supervised classifiers are performed for land-use classifications of grouped sub-zones. Information
obtained from the spatial zoning, Tasseled Cap transformation and Normalized Difference Vegetation Index, is also utilized
to facilitate the supervised classification process. Finally, a detailed land-use map is produced, with an overall classification
accuracy of 77.8%. Results show that dominant agricultural land uses of sub-zones are changed with historical reclamation
years, from saline lands with wildgrass (very recently reclaimed) to aqua-farm ponds, to cotton fields, and to paddy fields
and orchards (very early reclaimed). This transform process is primarily affected by soil salinities, and according to a soil
survey an electrical conductivity of saturation extract decreased from 7.3 ds/m in the saline land reclaimed in 1996 to below
2 ds/m in the land reclaimed before 1969. The study concludes that multi-temporal remotely sensed images are important and
effective data sources for monitoring the rapid changes of coastal land uses. 相似文献
525.
526.
The Spatio-Temporal Dynamic Pattern of Rural Residential Land in China in the 1990s Using Landsat TM Images and GIS 总被引:2,自引:0,他引:2
Through interpreting Landsat TM images, this study analyzes the spatial distribution of rural settlements in China in 2000.
It calculates rural residential land percentage for every 1-km2 cell. The entire country is divided into 33 regions to investigate the spatio-temporal dynamic patterns of rural residential
land during the 1990s. According to the remote sensing survey, the rural residential land increased by 7.88 × 105 ha in the 1990s. The increment of rural residential land was 0.55 million ha in 1990–1995 and 0.23 million ha in 1995–2000.
In 1990–1995, rural residential land increased dramatically in the eastern regions such as the Yangtze River Delta, Pearl
River Delta, and North China Plain, accounting for 80.80% of the national growth; the expansion in the western regions was
much more moderate. In 1995–2000, the expansion of rural residential land in eastern regions slowed, accounting for only 58.54%
of the increase at the national level, whereas the expansion in the western regions accelerated. Rapid rural residential development
resulted from increasing home construction and the limited control on rural land. The great regional disparity reflected the
regional economic development and land-use policy change. Our finding shows that nearly 60% of the rural residential area
came from cropland. 相似文献
527.
528.
Modeling Urban Growth Effects on Surface Runoff with the Integration of Remote Sensing and GIS 总被引:18,自引:0,他引:18
Weng Q 《Environmental management》2001,28(6):737-748
A methodology is developed to relate urban growth studies to distributed hydrological modeling using an integrated approach
of remote sensing and GIS. This linkage is possible because both studies share land-use and land-cover data. Landsat Thematic
Mapper data are utilized to detect urban land-cover changes. GIS analyses are then conducted to examine the changing spatial
patterns of urban growth. The integration of remote sensing and GIS is applied to automate the estimation of surface runoff
based on the Soil Conservation Service model. Impacts of urban growth on surface runoff and the rainfall–runoff relationship
are examined by linking the two modeling results with spatial analysis techniques. This methodology is applied to the Zhujiang
Delta of southern China, where dramatic urban growth has occurred over the past two decades, and the rampant urban growth
has created severe problems in water resources management. The results revealed a notably uneven spatial pattern of urban
growth and an increase of 8.10 mm in annual runoff depth during the 1989–1997 period. An area that experienced more urban
growth had a greater potential for increasing annual surface runoff. Highly urbanized areas were more prone to flooding. Urbanization
lowered potential maximum storage, and thus increased runoff coefficient values. 相似文献
529.
Ming-Der Yang Carolyn J. Merry Robert M. Sykes 《Journal of the American Water Resources Association》1999,35(2):253-263
ABSTRACT: Water quality modeling has been developed for more than three quarters of a century, but is limited to the study of trends instead of making accurate short-term forecasts. A major barrier to water quality forecasting is the lack of an efficient system for water quality monitoring. Traditional water quality sampling is time-consuming, expensive, and can only be taken for small sizes. Remote sensing provides a new technique to monitor water quality repetitively for a large area. The objective of this research is to use remotely sensed data in a water quality model - QUAL2E - in a case study of the Te-Chi Reservoir in Taiwan. The water quality variables developed from the simulations are displayed in map form. The developed forecasting system is designed to predict water quality variables using remote sensing data as an input to initialize and update water quality conditions. 相似文献
530.
近年来,随着抗生素的滥用和不加控制的排放,水体中抗生素的检测已经成为环境分析的一个重要研究领域.本文采用简单的超声方法将超薄石墨相氮化碳纳米片(g-C3N4Ns)固定在氧化石墨烯(GO)的表面,形成g-C3N4Ns/GO纳米复合材料,制备了一种基于石墨相氮化碳/氧化石墨烯的新型电化学传感器,用于环境水样中左氧氟沙星(LEV)的检测.在优化的实验条件下,利用差分脉冲伏安法(DPV)对LEV进行检测,线性范围为0.25~90μmol·L-1,检出限为0.073μmol·L-1.该传感器具有良好的稳定性、灵敏度、抗干扰能力和制备简单等优势,并成功地用于测定河水和自来水样中的LEV,具有良好的回收率,为左氧氟沙星的灵敏检测提供了一种可行的方案. 相似文献