1208-1369年陕甘宁交界地区干湿变化

More than 240 items of historical records containing climatic information were retrieved from official historical books, local chronicles, annals and regional meteorological disaster yearbooks. By using moisture index and flood/drought (F/D) index obtained from the above information, the historical climate change, namely wet-dry conditions in borderland of Shaanxi Province, Gansu Province and Ningxia Hui Autonomous Region (BSGN, mainly included Ningxialu, Hezhoulu, Gongchanglu, Fengyuanlu and Yan’anlu in the Yuan Dynasty) was studied. The results showed that the climate of the region was generally dry and the ratio between drought and flood disasters was 85/38 during the period of 1208–1369. According to the frequencies of drought-flood disasters, the whole period could be divided into three phases. (1) 1208–1240: drought dominated the phase with occasional flood disasters. (2) 1240–1320: long-time drought disasters and extreme drought events happened frequently. (3) 1320–1369: drought disasters were less severe when flood and drought disasters happened alternately. Besides, the reconstructed wet-dry change curve revealed obvious transition and periodicity in the Mongol-Yuan Period. The transitions occurred in 1230 and 1325. The wet-dry change revealed 10- and 23-year quasi-periods which were consistent with solar cycles, indicating that solar activity had affected the wet-dry conditions of the study region in the Mongol-Yuan Period. The reconstructed results were consistent with two other study results reconstructed from natural evidences, and were similar to another study results from historical documents. All the above results showed that the climate in BSGN was characterized by long-time dry condition with frequent severe drought disasters during 1258 to 1308. Thus, these aspects of climatic changes might have profound impacts on local vegetation and socio-economic system.     

遥感影像变化检测自适应阈值分割的Kriging方法

提出了一种基于空间统计理论的自适应阈值分割方法,用于多时相高分辨率遥感影像变化检测研究。针对未确定类别的目标像素点,分别以局部区域内的变化类和非变化类为样本点,将目标点的实际值和估计值进行比较,以确定目标点的类别。为验证本方法的优越性和自适应性,分别与系列传统阈值分割方法进行了对比分析。实验结果表明,本方法能够有效去除伪变化信息,减少目标的错判、误判率,提高检测精度。     

气候变化对里海水位的影响（英文）

目前,关于里海的两个主要问题是水位变化及其生态条件。历史上,里海的海水入侵和衰退对该区域的生活和生产有很大影响。应用地质数据、历史数据和考古数据,以及观测数据,本文对地质历史时期里海水位的变化、年度和季度变化以及短期的波动进行了研究。文章对解释里海水位波动的两种不同的方法进行了论述,并认为里海水位变化是受地质、水文气候和水量平衡以及人类活动等因素的影响的多级过程,其中主要影响因素为水文气候的变化。     

柽柳灌丛沙堆及丘间地蚀积分布随背景植被变化的风洞实验

以塔克拉玛干沙漠南缘沙漠-绿洲过渡带广泛分布的柽柳灌丛沙堆及丘间地植物为原型,依据风沙运动相似理论,制作背景植被盖度依次为0%、4%、10%、16%和26%五组灌丛沙堆模型,在风洞中进行蚀积变化规律模拟实验。结果表明：柽柳灌丛沙堆及丘间地蚀积分布可划分为6个区域,依次为沙堆前积沙区、沙堆迎风坡风蚀区、沙堆两侧风蚀区、沙堆背风侧涡流积沙区、沙堆后尾流积沙区和不受沙堆影响区。随着指示风速增大,沙堆前积沙区和尾流积沙区范围缩小而沙堆两侧风蚀区面积明显增大。随着背景植被盖度的增大,沙堆前积沙区和尾流积沙区范围增大而沙堆两侧风蚀区范围明显减小。灌丛沙堆及丘间地整体风蚀面积比、风蚀率、各分区蚀积强度均呈指数规律递减。背景植被盖度为0%时,灌丛沙堆影响区风蚀率明显高于不受沙堆影响区,说明裸露地表条件下灌丛沙堆的存在会加剧地表风蚀;当背景植被盖度为4%~16%时,灌丛沙堆影响区风蚀率均低于不受沙堆影响区,可见丘间地植被存在可使灌丛沙堆起到一定的防风阻沙作用。当背景植被盖度>16%时,柽柳灌丛沙堆及丘间地整体蚀积强度和风蚀率变化趋于平稳。据此认为维持不低于16%的背景植被覆盖,是沙漠-绿洲过渡带柽柳灌丛沙堆科学保育的关键。     

贵州乌蒙山区资源相对承载力的时空动态变化

贵州乌蒙山区是国家划定的18片贫困区之一,随着人口增长和社会经济发展的加速,山区人地资源矛盾日趋突出,已严重阻碍了乌蒙山区社会经济的可持续发展。运用并改进了相对资源承载力的研究思路和计算方法,研究了1995~2006年贵州乌蒙山区自然资源、经济资源、生活水平的相对承载力和综合承载力的时空动态变化过程。对于认清和把握乌蒙山区资源承载力变化规律,完善山区资源环境承载力研究成果具有重要指导意义。研究表明:贵州乌蒙山区人口严重超载,而承载人口的主要资源为土地资源,经济资源和生活水平承载力偏低;相对资源承载力空间差异显著,绝大多数县域综合承载力均处于超载状态。     

江苏淤泥质潮滩对海平面变化的形态响应

通过对江苏滨海平原淤泥质潮滩1980年以来19个固定潮滩断面112个测次滩面高程测量的统计分析，探讨典型淤泥质潮滩剖面形态对海平面变化的形态响应过程。结果表明，典型淤涨岸段海平面上升，多年平均潮位线以上滩面仍将淤积加高，但淤高幅度除多年平均高潮线附近滩面相对较大外，其余均较小，表明随海平面上升该滩带总体淤积速率将趋于减小；与此相反，多年平均潮位线以下滩面则趋于蚀低，且侵蚀强度较大，表明该滩带的侵蚀有加剧趋向，最终滩面总体形态将因上带不断淤高和下带不断蚀低而逐渐变陡，剖面上凸形态的曲率不断加大。曲型侵蚀岸段，海平面上升的效应则相反，海平面上升，多年平均潮位线以上滩面强烈蚀低；而多年平均潮位线以下滩面则强烈淤积加高，剖面的上凹形态最终将因上带不断蚀低和下带不断淤高而趋于平直。     

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Land use and land cover change in Liaocheng Prefecture of China

1 Introduction1.1 Introduction to Liaocheng PrefectureLiaocheng Prefecture lies in northwest of Shandong Province and slightly north to the center of the Huang-Huai-Hai Plain with latitudes between 35(47'N and 37(02'N and longitudes between 115(16'E and 116(32'E. Administratively, it consists of two cities (Liaocheng and Linqing) and six counties (Yanggu, Shenxian, Chiping, Dong'e, Guanxian and Gaotang). It covers a total area of 8590 km2 with a maximum distance of 114 km from eas…     

流域生态水文模型研究进展

流域生态水文模型是全球变化下流域生态水文响应研究的重要工具,通过定量刻画植被与水文过程的相互作用及全球变化对流域生态水文过程演变的影响机制,为流域水资源管理和生态恢复提供科学支撑,是生态水文研究的前沿和热点.基于植被与水文过程相互作用规律,流域生态水文模型一方面要充分描述植被与水文过程相互作用和互为反馈机制,另一方面要...     

Impacts of land use changes on groundwater resources in the Heihe River Basin

Land use and land cover changes have a great impact on the regional hydrological process. Based on three periods of remote sensing data from the 1960s and the long-term observed data of groundwater from the 1980s, the impacts of land use changes on the groundwater system in the middle reach of Heihe River Basin in recent three decades are analyzed by the perspective of groundwater recharge and discharge system. The results indicate that with the different intensities of land use changes, the impacts on the groundwater recharge were 2.602×108 m3/a in the former 15 years (1969-1985) and 0.218×108 m3/a in the latter 15 years (1986-2000), and the impacts on the groundwater discharge were 2.035×108 m3/a and 4.91×108 m3/a respectively. When the groundwater exploitation was in a reasonable range less than 3.0×108 m3/a, the land use changes could control the changes of regional groundwater resources. Influenced by the land use changes and the large-scale exploitation in the recent decade, the groundwater resources present apparently regional differences in Zhangye region. Realizing the impact of land use changes on groundwater system and the characteristics of spatial-temporal variations of regional groundwater resources would be very important for reasonably utilizing and managing water and soil resources.