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991.
Real-time monitoring and early warning of landslides at relocated Wushan Town,the Three Gorges Reservoir,China 总被引:12,自引:6,他引:6
A special monitoring and warning system has been established and improved in the Three Gorges Reservoir area since 1999. It
is necessary to develop a real-time monitoring system on landslides because there are dense populations centered in the reservoir
area and geo-hazards may be triggered by a 30-m water level fluctuation between 145 and 175 m in elevation during reservoir
operation; the regular monitoring could not be suitable to the early warning on landslides. Since 2003, the authors have carried
out a real-time monitoring and early warning project on landslides at the relocated Wushan town in the Three Gorges Reservoir
area. The monitoring station includes Global Positioning System with high-accuracy double frequency to monitor ground displacement,
time domain reflection technology, and immobile borehole, inclinometer to monitor deep displacement, piezometer to monitor
pore water pressure, and precipitation and reservoir water level monitoring. Compared with traditional methods, the real-time
monitoring is continuous and traceable in the acquisition process, and the cycle of data acquisition is very short, usually
within hours, minutes, or even shorter. Based on the landslide monitoring experience at the Three Gorges Reservoir area, the
early warning criteria on landslide are established in which the critical situation is classified into four levels: blue,
yellow, orange, and red, respectively, expressed by no, slight, moderate, and high risk situation. Comprehensive judgment
from multimonitoring data of Yuhuangge landslide in this area since 2004 suggested that the new Wushan town will be at the
blue early warning level, although some monitoring data of individual displacement at deep borehole showed that the displacement
was increased by 5 mm in 5 months with an average velocity of 1.0 mm/month, and the data of BOTDR also showed an obvious dislocation
along a stairway on the landslide. 相似文献
992.
Hydraulic redistribution in the Inner Mongolia Huangfuchuan basins under different climate scenarios
This paper describes the scaling up to a day scale of the Ryel hour scale model incorporating the process of hydraulic redistribution
(HR). The Ryel model was applied to the Inner Mongolia Huangfuchuan basins to analyze transpiration, evaporation and stomatal
conductance of Artemisia tridentate, and to indicate the added value of the feedback by comparing simulations with and without incorporating HR. Five climate
scenarios were designed based on 40-y continuous climate data from the study area and the response of HR to the different
climate scenarios was modeled. Under 1991 climate conditions, cumulative transpiration and evaporation with HR during the
growing season were 161.7 mm and 206.14 mm, respectively, compared with transpiration of 140.7 mm and evaporation of 174.2
mm without HR. Under the five different climate change scenarios, HR influenced evaporation more than transpiration. The effect
of HR on transpiration, evaporation and stomatal conductance was very different among the scenarios. Inclusion of HR gave
rise to the largest increase in transpiration and evaporation under the T2P0 scenario and the smallest under the T2P2 scenario,
but transpiration and evaporation decreased under the T0P-2 scenario. Stomatal conductance significantly increased with the
inclusion of HR. The model used in this study has potential benefits for incorporating HR into soil processes, such as water
movement and mass transfer. 相似文献
993.
994.
Hong Zhang Hung-Lung Huang Agnes Lim Robert Holz Steve Dutcher Fred Nagle Liam Gumley Jinnian Wang Runhe Shi Wei Gao 《Frontiers of Earth Science》2010,4(3):363-373
The Atmospheric Infrared Sounder (AIRS) and MODerate-Resolution Imaging Spectroradiometer (MODIS) on board NASA Earth Observing
System (EOS) Aqua spacecraft measure the upwelling infrared radiance used for numerous remote-sensing- and climate-related
applications. AIRS provides high spectral resolution infrared radiances, while MODIS provides collocated high spatial resolution
radiances at 16 broad infrared bands. An optimal algorithm for cloud-clearing has been developed for AIRS cloudy soundings
at the University of Wisconsin-Madison, where the spatially and spectrally collocated AIRS and MODIS data has been used to
analyze the characteristic of this algorithm. An analysis and characterization of the global AIRS cloud-cleared radiances
using the bias and the standard deviation between the cloud-cleared and the nearby clear measurements are studied. Scene inhomogeneity
for both land- and water-surface types has been estimated to account for the assessed error. Both monthly and seasonal changes
of global AIRS/MODIS cloud-clearing performance also have been analyzed. 相似文献
995.
乌兰陶勒盖水源地位于毛乌素沙漠腹地,地表水体不发育,植被生态相对脆弱。水源地大规模开采引发的地下水位下降将会对区内的植被生态造成一定的破坏。采用样方调查方法,对区内植被生态现状进行了调查,将区内植被分为荒漠、低湿和沙地三种植被类型;对植被覆盖度与地下水位的关系进行了探讨,得出植被生存的最佳水位是1.1~3.0m;运用GIS软件对区内植物现状与地下水位埋深进行了敏感性分区研究。试探性的建立开采条件下的植被生态风险指数,并根据指数值的大小进行风险性分区,结果表明,在选定的开采方案下,高风险区和中风险区的分布面积较小,而低风险区的面积最大,从而说明在乌兰陶勒盖水源地新增地下水开采量11.82万m3/d的情况下,不会对生态植被造成大的影响。 相似文献
996.
在分析矿区地质及水文地质条件的基础上,以冯家塔煤矿1201工作面为例,论述了府谷矿区矿井突水因素,认为大气降水、岩溶水和地表水是矿井充水的主要水源,断层、采煤形成的裂隙带是矿井充水的通道,小煤矿采空区是未来煤矿安全生产的重大隐患。运用突水系数和水文地质实验法,对矿区的突水危险区域进行了评价,指出井田西北部突水系数大于0.6,可能存在突水危险;清水川地堑断裂带内富水性及导水性弱,对煤层开采不会造成威胁。最后提出了加强矿井水文地质勘查、做好矿井涌水量观测等矿井防治水建议。 相似文献
997.
Heavy metal contamination of cultivated wetland soils along a typical plateau lake from southwest China 总被引:3,自引:0,他引:3
Junhong Bai Baoshan Cui Zhifeng Yang Xiaofeng Xu Qiuyi Ding Haifeng Gao 《Environmental Earth Sciences》2010,59(8):1781-1788
Topsoil (0–20 cm) samples were collected from four cultivated wetlands including Northern and Western Fields (about 30-year
tillage), and Southern and Western Fields (about 20-year tillage) along the Yilong Lake of China in October, 2005. Total concentrations
of As, Cr, Cu, Pb, and Zn were determined using the inductively coupled plasma atomic absorption spectrometry in order to
assess contamination status in four sampling plots. Results showed that the average concentrations of these heavy metals in
Northern and Western Fields were significantly (P < 0.01) higher than those in reference soils, while they were generally lower in Southern and Eastern Fields. All the mean
concentrations of heavy metals were lower, except that the average concentrations of As and Cr in Northern Field slightly
exceeded the soil quality guidelines. The contamination indices showed low-contamination levels for As, Cu, Pb, and Zn in
Northern and Western Fields, while no contamination levels could be observed in Southern and Eastern Fields. As for Cr, they
showed moderate-contamination levels in Northern Field, but low or no contamination levels in other three Fields. The integrated
contamination index values indicated Northern and Western Fields were moderately contaminated, while Southern and Eastern
Fields were less contaminated. The same contamination sources of these heavy metals were identified in these fields using
factor- and cluster analysis. 相似文献
998.
Disposal of saline subsurface drainage waters from croplands into evaporation basins (or ponds) in the San Joaquin Valley
of California causes excessive accumulation of salts and elevated concentrations of arsenic (As), a potentially high risk
element with little information about its fate, in the agricultural evaporation ponds. We examined dissolved As concentration,
speciation, and distribution in waters as well as As fractionation in sediments in the 10-cell South Evaporation Basin for
better understanding of processes and conditions affecting As transformations and fate in a specific drainage disposal facility.
The increase of total dissolved As concentrations were observed with higher Cl− and electric conductivity along flow path indicating that evaporation was an important factor regulating total dissolved
As concentration. The increases of reduced As species such as arsenite [As(III)] and organic As (monomethylarsonic acid and
dimethylarsinic acid) were found towards the terminal flow pathway. However, arsenate [As(V)], the oxidized species remained
greater than 67% of total dissolved As in all cell waters. Sequential extractions of sediments indicated that reducing conditions
may influence As behavior in sediments to be more soluble and exchangeable. Arsenic association with oxides was appreciable
only under oxidizing condition. Carbonate minerals played an important role in immobilizing As into the sediments under alkaline
condition and a broad range of redox conditions. However, these sink mechanisms did not significantly reduce As concentrations
in the cell waters. The reducing condition facilitated by high concentration of organic matter might be a major factor for
the increase in As mobility. 相似文献
999.
Guangquan Chen Bochao Xu Shibin Zhao Disong Yang William C.Burnett Shaobo Diao Maosheng Gao Xingyong Xu Lisha Wang 《海洋学报(英文版)》2022,41(1):11-20
Submarine groundwater discharge(SGD) has received increasing attention by studies on coastal areas; however,its effects on biogeochemical zonation have not been investigated to date. The Huanghe River Estuary(HRE) is a world class river estuary with high turbidity, and heavy human regulation. This study investigated how SGD is related to the benthic biogeochemistry of the HRE. Based on the distribution of several parameters(e.g., salinity,temperature, dissolved oxygen(DO) levels, p H, radium iso... 相似文献
1000.
Hypoxia is increasingly reported off the Changjiang River Estuary with the confluence of multiple high volume nutrient sources. The Regional Ocean Modeling System coupled with a biological model was used to analyze the effect of different nutrient sources on the development of hypoxia off the Changjiang River Estuary. By comparing to observed data, our model suitably captured the regional dynamics of chlorophyll a, dissolved oxygen, and nutrient concentration. A series of sensitivity experiments were conducted to investigate the hypoxia response to the various nutrient sources, such as loading from the Changjiang River, Kuroshio and Taiwan Warm Current. Our model results indicated that nutrients from different sources significantly influenced the hypoxia off the Changjiang River Estuary, and it was mostly affected by nutrients sourced from the Kuroshio. The nutrients input from the Changjiang River had larger impacts on the hypoxia in the north of 30°N than that in the south of 30°N. The nutrients sourced from the Taiwan Strait had a least influence on the hypoxia off the Changjiang River Estuary. 相似文献