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The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial use.The water source area of the MR-SNWDP is the region that is most sensitive to and most affected by the construction of this water diversion project.In this study,we used Landsat Thematic Mapper(TM)and HJ-1 A/B images from 2000 to 2015 by an object-based approach with a hierarchical classification method for mapping land cover in the water source area.The changes in land cover were illuminated by transfer matrixes,single dynamic degree,slope zones and fractional vegetation cover(FVC).The results indicated that the area of cropland decreased by 31%and was replaced mainly by shrub over the past 15 years,whereas forest and settlements showed continuous increases of 29.2% and 77.7%,respectively.The changes in cropland were obvious in all slope zones and decreased most remarkably(–43.8%)in the slope zone above 25°.Compared to the FVC of forest and shrub,significant improvement was exhibited in the FVC of grassland,with a growth rate of 16.6%.We concluded that local policies,including economic development,water conservation and immigration resulting from the construction of the MR-SNWDP,were the main drivers of land cover changes;notably,they stimulated the substantial and rapid expansion of settlements,doubled the wetlands and drove the transformation from cropland to settlements in immigration areas. 相似文献
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Journal of Geographical Systems - 相似文献
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研究华为P40手机终端北斗三频观测数据质量及噪声特性,通过与测量型接收机对比分析发现,P40手机海思芯片具有较好的北斗三号信号捕获能力,B1I、 B1C和B2a三频信号信噪比略低于测量型天线,且3个频点均存在与终端芯片相关的系统误差。外置天线零基线实验结果表明,P40手机海思芯片零基线定位精度达到mm级,伪距和载波相位噪声可达到测量接收机噪声精度水平,B2a伪距噪声优于0.5 m,3个频点的相位噪声均优于2 mm。 相似文献
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针对山区地形复杂、植被茂密,采用传统的测量手段进行高速公路勘测设计较为困难,且工期长的实际,本文提出了一种基于无人机载激光雷达技术的山区高速公路勘测设计的应用技术流程.该技术流程在河南济源沿太行高速公路勘测设计中得到应用,验证了其可行性及精度,表明无人机载激光雷达在山区高速公路勘测设计中能够提高生产效率及精度,节约成本. 相似文献
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针对GPT2w模型误差累积所导致的天顶对流层延迟(zenith tropospheric delay, ZTD)和大气可降水量(precipitable water vapor, PWV)精度不高的问题,利用2017年长三角地区7个探空站和2个GNSS站的实测数据检验GPT2w模型获取的气压、温度、水汽压、加权平均温度(Tm)和ZTD等参数的精度,并融合GNSS解算得到的ZTD(GNSS-ZTD)与GPT2w模型获取的气象参数,提高PWV反演精度。结果表明：1)近地面处的气压、温度和水汽压的bias分布在－3~4 mbar、－7~7 K和－9~2 mbar之间,精度较高;2)GPT2w模型获取的Tm在长三角地区适用性较好,年均bias和RMS分别为－1.21 K和6.89 K;3)基于GPT2w模型解算的ZTD的bias和RMS均值分别为1.4 cm和9.4 cm,精度明显低于基于实测气象数据获得的GNSS-ZTD;4)参数融合法计算的PWV与GNSS-PWV精度相当,该方法可用于无实测气象参数时实时获取PWV。 相似文献
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Variational safety factors and slip surfaces of slope using three-dimensional strength reduction analysis 总被引：1，自引：0，他引：1
Hang Lin Wenwen Zhong Ping Cao Taoying Liu 《Journal of the Geological Society of India》2013,82(5):545-552
This paper describes the effect of boundary conditions combined with geometric and strength parameters on slope stability, including safety factor and slip surface, using numerical strength reduction analysis. The different boundary conditions are discussed, which include the fully restrained boundary, half-restrained boundary, and free boundary on the safety factor of slope. The effects of geometric and strength parameters on the safety factor of slope are then examined. Discrepancies between the slip surface shape and the escaping points are also presented to assess slope stability. 相似文献
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