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11.
Productive wetland systems at land-water interfaces that provide unique ecosystem services are challenging to study because of water dynamics, complex surface cover and constrained field access. We applied object-based image analysis and supervised classification to four 32-m Beijing-1 microsatellite images to examine broad-scale surface cover composition and its change during November 2007-March 2008 low water season at Poyang Lake, the largest freshwater lake-wetland system in China (> 4000 km2). We proposed a novel method for semi-automated selection of training objects in this heterogeneous landscape using extreme values of spectral indices (SIs) estimated from satellite data. Dynamics of the major wetland cover types (Water, Mudflat, Vegetation and Sand) were investigated both as transitions among primary classes based on maximum membership value, and as changes in memberships to all classes even under no change in a primary class. Fuzzy classification accuracy was evaluated as match frequencies between classification outcome and a) the best reference candidate class (MAX function) and b) any acceptable reference class (RIGHT function). MAX-based accuracy was relatively high for Vegetation (≥ 90%), Water (≥ 82%), Mudflat (≥ 76%) and the smallest-area Sand (≥ 75%) in all scenes; these scores improved with the RIGHT function to 87-100%. Classification uncertainty assessed as the proportion of fuzzy object area within a class at a given fuzzy threshold value was the highest for all classes in November 2007, and consistently higher for Mudflat than for other classes in all scenes. Vegetation was the dominant class in all scenes, occupying 41.2-49.3% of the study area. Object memberships to Vegetation mostly declined from November 2007 to February 2008 and increased substantially only in February-March 2008, possibly reflecting growing season conditions and grazing. Spatial extent of Water both declined and increased during the study period, reflecting precipitation and hydrological events. The “fuzziest” Mudflat class was involved in major detected transitions among classes and declined in classification accuracy by March 2008, representing a key target for finer-scale research. Future work should introduce Vegetation sub-classes reflecting differences in phenology and alternative methods to discriminate Mudflat from other classes. Results can be used to guide field sampling and top-down landscape analyses in this wetland. 相似文献
12.
Characterization of terrestrial water dynamics in the Congo Basin using GRACE and satellite radar altimetry 总被引:1,自引:0,他引:1
Hyongki Lee R. Edward Beighley Hahn Chul Jung Jianbin Duan Dai Yamazaki 《Remote sensing of environment》2011,115(12):3530-3538
The Congo Basin is the world's third largest in size (~ 3.7 million km2), and second only to the Amazon River in discharge (~ 40,200 m3 s− 1 annual average). However, the hydrological dynamics of seasonally flooded wetlands and floodplains remains poorly quantified. Here, we separate the Congo wetland into four 3° × 3° regions, and use remote sensing measurements (i.e., GRACE, satellite radar altimeter, GPCP, JERS-1, SRTM, and MODIS) to estimate the amounts of water filling and draining from the Congo wetland, and to determine the source of the water. We find that the amount of water annually filling and draining the Congo wetlands is 111 km3, which is about one-third the size of the water volumes found on the mainstem Amazon floodplain. Based on amplitude comparisons among the water volume changes and timing comparisons among their fluxes, we conclude that the local upland runoff is the main source of the Congo wetland water, not the fluvial process of river-floodplain water exchange as in the Amazon. Our hydraulic analysis using altimeter measurements also supports our conclusion by demonstrating that water surface elevations in the wetlands are consistently higher than the adjacent river water levels. Our research highlights differences in the hydrology and hydrodynamics between the Congo wetland and the mainstem Amazon floodplain. 相似文献
13.
负荷及温度对人工湿地去除氨氮的影响 总被引:3,自引:0,他引:3
本研究在借鉴他人研究成果的基础上,利用海泡石这一江西特有的矿物质为基质,辅以香根草等适应环境能力强,去污效果好的植物,构成海泡石人工湿地系统。通过试验发现,该人工湿地对生活污水中氨氮具有良好的去除效果。 相似文献
14.
水是维系湿地生态系统的基本要素之一.目前,扎龙湿地人工补水、调水缺乏基础资料支撑.扎龙湿地由于其为丹顶鹤和其他鸟类提供繁殖地和迁徙停歇地成为亚洲著名湿地之一.笔者自2005年在扎龙湿地做水资源监测,监测内容主要包括水位和水量的变化以及降水、蒸发等水文气象要素.由于人类活动的长期影响,湿地水资源分流受到严重威胁,如水利工程的建设割裂了区内水资源系统的自流格局与自然分配机制;同时,区域性的干旱,加剧了保护区水资源的短缺矛盾.通过2005-2008年共4 a的水文监测,初步摸清了湿地来水的传播路径,掌握了来水、退水过程和湿地核心区水位变化. 相似文献
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16.
Philip Yuan 《Architectural Design》2016,86(2):92-99
Philip Yuan , Founding Director of Shanghai-based firm Archi-Union Architects, applies parametric techniques to his design and research in China. Here he explains how Parametricism can provide a highly adaptive and open approach to architectural knowledge and spatial organisation, accommodating regional variations in culture and environment, through an emphasis on local climate, materials and craft traditions. 相似文献
17.
湿地公园植物群落构景营造具有特殊性,本文以西安浐灞国家湿地公园为研究对象,依托景观生态学理论。从湿地公园的功能角度考虑,根据湿地环境的不同特点,从陆生、湿生、水生、岛屿四种环境特点总结出浐灞湿地公园植物群落组合的营造模式。 相似文献
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该文以武汉市东湖国家湿地公园为研究对象,通过对东湖国家湿地公园的现状调查,结合湿地公园景观营建相关资料,分析了东湖国家湿地公园与武汉市及东湖风景区的关系,阐述了东湖国家湿地公园中景观构成要素的营建方式。在此基础上,归纳了城市湖泊型湿地公园的特性,并分别从植被、湖岸带、水环境及人工设施等方面分析探讨城市湖泊型湿地公园景观营建方法。通过对东湖国家湿地公园的景观营建分析及城市湖泊型湿地公园景观营建方法的探索,为完善东湖湿地公园建设及城市湖泊型湿地公园景观营建提供指导策略及参考。 相似文献
20.
Andreas Zehnsdorf Norman Stock Juliane Richter Michael Blumberg Roland A. Müller 《化学,工程师,技术》2016,88(8):1138-1144
There is increasing interest worldwide in the decentralized treatment of gray water. Since ground‐level areas are generally costly, gray‐water treatment can also be carried out using helophyte mats on the roofs of buildings as an alternative. Alongside the water treatment itself, this process also has a positive effect on the indoor climate in the building. In a test carried out under realistic conditions, it was shown that a helophyte mat with a root‐layer depth of 0.1 m and with hydraulic loads per unit up to 15 L m?2d?1 is suitable for treating typical gray water from a residential building. 相似文献