[Objective] The aim was to analyze the correlation between tree-ring width of Picea crassifolia in the east of Qilian Mountains and the precipitation, temperature and the normalized difference vegetation index (NDVI)....[Objective] The aim was to analyze the correlation between tree-ring width of Picea crassifolia in the east of Qilian Mountains and the precipitation, temperature and the normalized difference vegetation index (NDVI). [Method] The correlation analysis and the regression analysis were used in this study. [Result] The tree-ring width was significantly correlated with the autumn precipitation and the spring average NDVI. The conversion equation between tree-ring width and spring NDVI (R2 = 48.5% , R2adj =46.2% , F =21.627, P <0.001) was developed and NDVI sequence was reconstructed during the period 1915 -2007. The drought in the 1920s was pronounced. Vegetation cover in the Qilian Mountains increased during the period 1922-1934, 1940-1957, 1965-1969, 1984-1988 and 1995-1997, but decreased during 1935 -1939, 1958 -1964, 1970 -1983, 1989 -1994 and 1998 -2005. [Conclusion] The reconstructed NDVI showed the drought evolution in the study area.展开更多
祁连山东段金塔河流域分布着两级夷平面(山顶面与主夷平面)、一级剥蚀面和多级河流阶地,它们是晚新生代青藏高原阶段性隆升的产物。通过电子自旋共振(Electronspinresonance ,简写为ESR)、热释光(Lumines cence ,简写为TL)、红外释光(In...祁连山东段金塔河流域分布着两级夷平面(山顶面与主夷平面)、一级剥蚀面和多级河流阶地,它们是晚新生代青藏高原阶段性隆升的产物。通过电子自旋共振(Electronspinresonance ,简写为ESR)、热释光(Lumines cence ,简写为TL)、红外释光(Infra redstimulatedluminescence ,简写为IRSL)和14 C等绝对测年手段并结合区域对比的研究表明,该区山顶面形成于老第三纪,主夷平面形成于中新世至上新世,剥蚀面解体于1 4MaB P 左右。其后金塔河流域发育5～6级阶地,形成时代大致为1 2 4MaB P 、0 78MaB P 、0 14MaB P 、0 0 6MaB P 、0 0 3MaB P 和0 0 1MaB P 。结合河流阶地的形成年代、发育特征以及邻区阶地的发育模式研究表明。展开更多
根据自然灾害系统理论和冰雹灾害风险评估的相关理论,选择冰雹多发地区的祁连山东端天祝藏族自治县为研究区,并基于天祝县和周边常规气象站观测资料、历史灾情资料和基础地理信息数据,探索和研究县级冰雹灾害风险区划的技术方法。通过...根据自然灾害系统理论和冰雹灾害风险评估的相关理论,选择冰雹多发地区的祁连山东端天祝藏族自治县为研究区,并基于天祝县和周边常规气象站观测资料、历史灾情资料和基础地理信息数据,探索和研究县级冰雹灾害风险区划的技术方法。通过分析致灾因子危险性、孕灾环境敏感性、承载体易损性以及防灾减灾能力4个指标,建立了冰雹灾害风险评估模型,并利用GIS(Geographic Information System)技术得到了天祝县冰雹灾害风险区划。结果显示:天祝藏族自治县冰雹灾害风险南高北低,其中华藏寺、东坪、石门、打柴沟大部及炭山岭和赛什斯的局部发生冰雹灾害的风险最高;哈溪、朵什、西大滩次之;松山的东部、旦马、祁连西南部为冰雹低风险区。展开更多
基金Supported by the NSFC(41071128 and 40801004)the Key Program of Hebei Education Department(ZH2012035)
文摘[Objective] The aim was to analyze the correlation between tree-ring width of Picea crassifolia in the east of Qilian Mountains and the precipitation, temperature and the normalized difference vegetation index (NDVI). [Method] The correlation analysis and the regression analysis were used in this study. [Result] The tree-ring width was significantly correlated with the autumn precipitation and the spring average NDVI. The conversion equation between tree-ring width and spring NDVI (R2 = 48.5% , R2adj =46.2% , F =21.627, P <0.001) was developed and NDVI sequence was reconstructed during the period 1915 -2007. The drought in the 1920s was pronounced. Vegetation cover in the Qilian Mountains increased during the period 1922-1934, 1940-1957, 1965-1969, 1984-1988 and 1995-1997, but decreased during 1935 -1939, 1958 -1964, 1970 -1983, 1989 -1994 and 1998 -2005. [Conclusion] The reconstructed NDVI showed the drought evolution in the study area.
文摘祁连山东段金塔河流域分布着两级夷平面(山顶面与主夷平面)、一级剥蚀面和多级河流阶地,它们是晚新生代青藏高原阶段性隆升的产物。通过电子自旋共振(Electronspinresonance ,简写为ESR)、热释光(Lumines cence ,简写为TL)、红外释光(Infra redstimulatedluminescence ,简写为IRSL)和14 C等绝对测年手段并结合区域对比的研究表明,该区山顶面形成于老第三纪,主夷平面形成于中新世至上新世,剥蚀面解体于1 4MaB P 左右。其后金塔河流域发育5～6级阶地,形成时代大致为1 2 4MaB P 、0 78MaB P 、0 14MaB P 、0 0 6MaB P 、0 0 3MaB P 和0 0 1MaB P 。结合河流阶地的形成年代、发育特征以及邻区阶地的发育模式研究表明。
文摘根据自然灾害系统理论和冰雹灾害风险评估的相关理论,选择冰雹多发地区的祁连山东端天祝藏族自治县为研究区,并基于天祝县和周边常规气象站观测资料、历史灾情资料和基础地理信息数据,探索和研究县级冰雹灾害风险区划的技术方法。通过分析致灾因子危险性、孕灾环境敏感性、承载体易损性以及防灾减灾能力4个指标,建立了冰雹灾害风险评估模型,并利用GIS(Geographic Information System)技术得到了天祝县冰雹灾害风险区划。结果显示:天祝藏族自治县冰雹灾害风险南高北低,其中华藏寺、东坪、石门、打柴沟大部及炭山岭和赛什斯的局部发生冰雹灾害的风险最高;哈溪、朵什、西大滩次之;松山的东部、旦马、祁连西南部为冰雹低风险区。
