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排序方式: 共有478条查询结果,搜索用时 328 毫秒
71.
D. H. A. AL-KHUDHAIRY C. LEEMHUIS V. HOFFMANN R. CALAON I. M. SHEPHERD J. R. THOMPSON 《水文科学杂志》2013,58(4):585-597
Abstract An understanding of hydrology is a prerequisite for ensuring the successful management, conservation and restoration of wetland environments. Frequently, however, little is known about historical hydrological conditions, such as water levels, within wetlands. Moreover, many channel and ditch systems in wetlands are not routinely monitored, except perhaps for research purposes. A methodology is presented herein which makes use of satellite imagery to indirectly provide remotely sensed observations of water levels within channels and ditches. Using multi-temporal Landsat Thematic Mapper (TM) imagery and simultaneous ground-based measurements of water levels, statistical relationships are established between satellite-derived effective wet ditch widths and measured water levels in the drainage system of the Elmley Marshes, southeast England. These relationships can be used subsequently to estimate historical ditch water levels and to monitor contemporary ditch water levels in the wetland. The study shows that satellite imagery has much to offer in monitoring changes in the hydrological regime of wetlands and in providing complimentary approaches to field monitoring. 相似文献
72.
《International Journal of Digital Earth》2013,6(1):130-147
Abstract Fresh water is arguably the most vital resource for many aspects of a healthy and stable environment. Monitoring the extent of surface water enables resource managers to detect perturbations and long term trends in water availability, and set consumption guidelines accordingly. Potential end-users of water-related observations are numerous and reflect society as a whole. They encompass scientists and managers at all levels of government, aboriginal groups, water/power utility managers, farmers, planners, engineers, hydrologists, medical researchers, climate scientists, recreation enthusiasts, public school to post-graduate students, many special interest groups and the general public. Water data and analyses generate information products that benefit water resources planning and management, engineering design, plant operations, navigation activities, health research, water quality assessments and ecosystem management. As well, they serve as inputs for flood and drought warnings and weather and climate prediction models. Radar data in general, and RADARSAT in particular, are very good for detecting open surface water and have been used operationally for flood monitoring in many countries. Significant radar data archives now exist to analyse seasonal, annual and decadal trends, in order to attain a better understanding of the freshwater cycle. Radar data are also useful for wetland classification and soil moisture estimation. With the increasing pressure on water resources, both from a quality as well as a quantity perspective, the need will continue to increase for reliable information. RADARSAT-2 has several innovations that will enhance the ability to provide useful information about water resources. This paper provides an overview of the use of radar in general, and RADARSAT-2 in particular, for the generation of information products useful to water resource managers. 相似文献
73.
国家林业局2009年启动第二次全国湿地资源调查,江西省开展并完成了这项工作。本文通过本次调查的操作细则和1996年首次调查进行比较分析,说明了本次调查手段先进、方法科学、数据丰富,同时展望了本次调查成果在江西省开展湿地资源管理上实现标准化、规范化、信息化方面的巨大作用。 相似文献
74.
云南楚雄龙川江流域上游的水库建设和河道渠化等工程改变了河谷盆地、缓坡、农耕地、河道、间歇性河流湿地和季节性溪流的地形和水文条件,曾经支持健康河流生态系统的间歇性湿地大面积退化,导致河流自净能力下降、植被退化以及生物多样性降低。通过调查和评估龙川江湿地,分析间歇性河流湿地生态修复的轨迹,确定修复目标、参考模型和技术路线,并制定湿地管理计划,旨在恢复健康的河流湿地环境。在湿地修复措施方面,挖掘和重新连接关键生态属性的湿地斑块,通过间歇性湿地保留雨水和流域的径流水量,实施综合种植计划,在河岸两侧恢复具有重要生态意义的季节性湿地综合体等。 相似文献
75.
76.
兰州银滩湿地区域生态经济价值评估 总被引:2,自引:2,他引:0
通过分析人工湿地的生态系统服务功能,阐述了黄河湿地生物多样性保护与水文调控生态功能区的重要性,计算了兰州银滩湿地的固碳释氧、空气质量调节、水源涵养和科研文化四项核心生态经济价值。结果表明:银滩湿地核心生态经济价值理论值为1 623.7万元,其中固碳释氧和科研文化价值实现率较高,分别为324.88万元和11.53万元。但现状水分供给、生态结构方面尚存在不合理之处,通过合理配置树草种构成,优化引水渠道等措施,该湿地将发挥更大的生态经济效益。 相似文献
77.
闽江河口湿地生态退化现状与保护对策 总被引:2,自引:0,他引:2
闽江河口湿地是福建省最重要的湿地之一,但该湿地正遭受不同程度的退化。通过实地调查,其退化类型可分为:面积减少退化型、生物多样性受损退化型、污染退化型、生物入侵退化型和泥沙淤积退化型。据此提出了闽江河口湿地生态保护的对策,保障闽江河口湿地生态环境与社会经济协调、稳定与可持续发展。 相似文献
78.
20世纪50-70年代的围湖垦殖与江汉平原湖泊湿地演化 总被引:1,自引:0,他引:1
利用相关资料并借助RS/GIS方法对20世纪50-70年代的大规模围垦情况进行了初步分析。结果表明:20世纪50年代、60年代、70年代、80年代0.1km2以上的湖泊总量分别是1309个、611个、612个、838个,湖泊总面积分别是8503.7km2、5467.5km2、2934.3km2、2977.3km2。湖泊数量和面积减少与围湖垦殖关系密切,江汉湖区平均面积变化率为65.0%,围垦具有明显的区域差异特征。围湖垦殖与江汉平原湿地演化关系密切,围湖垦殖降低了江汉平原湿地演化的可持续性。 相似文献
79.
Coastal salt-marshes represent an important coastal wetland system. The total area of coastal wetlands exceeds 5000 km2 in Jiangsu Province, China, but it is decreasing rapidly in response to the intense reclamation activities and coastal erosion along a part of the coastline. Hence, two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coastal areas, in order to protect the coastline from erosion and to increase the accumulation rate. Pb-210 and Cs-137 analyses were carried out for sediment samples from the salt-marshes of Wanggang to determine the sedimentation rate, on the basis of an evaluation of the background activity values and the factors affecting the enrichment of Pb-210. Analysis of a typical sediment column of the tidal flat shows that there is weak absorption of Pb-210 in the silt-dominated sediment. Because of the influences of factors such as storm events, bioturbation, material sources and analytical error, some abnormal data points appear in the Pb-210 record. After ignoring these data the calculated sedimentation rate was 3.3 cm yr-1 on average. Based upon analysis of the Cs-137 dating, the rate since 1963 was 3.1 cm yr-1 on average, similar to the data by Pb-210 dating and the previous studies. The dating results show that there were three stages of sedimentation, with the most rapid accretion being taking place after Spartina angelica was introduced into the area. The study also shows that at the stage of Spartina alterniflora growth, the accretion rate was higher than on the flat surface with the same elevation without the cover of this plant. 相似文献
80.
基于EOS/MODIS的若尔盖高原湿地定量遥感研究 总被引:1,自引:0,他引:1
研究旨在探讨EOS/MODIS影像提取若尔盖高原湿地信息的定量遥感方法.先计算MODIS影像的NDVI并将其线性变换到0~255;然后经多次试验确定区分湿地与非湿地的MODIS-NDVI阀值,并用人机交互式调整的方法消除误判像元及云的干扰,再多次试验得到区分湿地内部沼泽地和水体的阀值;通过统计不同类型湿地像元数计算湿地面积.研究表明,若尔盖高原湿地空间分布和面积具有季节差异,这与该地区降水和气温季节变化相关;采用MODIS-NDVI阀值并结合人机交互式调整的方法提取若尔盖高原夏半年的湿地信息是可行的,精度达到82%,而利用该方法提取冬半年湿地信息效果不甚理想,冬半年的MODIS影像湿地判识方法有待进一步探讨. 相似文献