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A tree-ring-width chronology of Pinus tabulaeformis from Kalaqin, Inner Mongolia was developed using modern dendrochronological techniques. Based on the results of correlation function analysis, the total precipitation from the previous August to current July was reconstructed for 1771?C2008 AD with an explained variance of 49.3%. The reconstruction correlated well with the dryness/wetness series derived from historical documents, as well as the precipitation reconstruction of the Chifeng-Weichang region. There were eight intervals with greater precipitation than the average (associated with the strong East Asian summer monsoon) and seven intervals lower than the average (weak monsoon). A power spectrum analysis showed that there were 120 a, 80 a, 8 a and 2 a periodicities.  相似文献   

3.
A tree-ring-width chronology of Pinus tabulaeformis from Kalaqin, Inner Mongolia was developed using modern dendroc hronological techniques. Based on the results of correlation function analysis, the total precipitation from the previous August to current July was reconstructed for 1771-2008 AD with an explained variance of 49.3%. The reconstruction correlated well with the dryness/wetness series derived from historical documents, as well as the precipitation reconstruction of the Chifeng-Weichang region. T...  相似文献   

4.
目的:对内蒙古呼伦贝尔市蚋类进行分类区系调查,初步摸清该地蚋相本底资料。方法:选择内蒙古呼伦贝尔市代表性地区,按常规方法采集幼蚋,经隔离培育出两性成虫,制片、鉴定;并据此对内蒙古蚋类名表进行更新和作相关讨论。结果:记载内蒙古呼伦贝尔市蚋科3属(原蚋属、后克蚋属和蚋属)22种,其中含5个新种及10个内蒙古新记录种。内蒙古蚋类更新至4属35种。结论:内蒙古具有蚋类多样性及明显的古北界区系特征。  相似文献   

5.
近15年来呼伦贝尔沙地土地沙漠化发展及其驱动力   总被引:4,自引:0,他引:4  
基于2001—2015年MODIS NDVI遥感数据反演了呼伦贝尔沙地近15年来植被覆盖度和沙漠化土地的空间格局与变化.结果表明:2001年以来呼伦贝尔沙地土地沙漠化总体有所减弱,但年际变化显著.其中:2001—2007年沙漠化土地以扩张为主;2007—2013年随植被覆盖缓慢恢复,沙漠化逐渐逆转;2013—2015年沙漠化有所加剧.降水量年际变化是该区沙漠化逆转或加剧最重要的驱动力.在气候变化背景下,未来几十年内该区沙漠化具有正过程发展趋势.  相似文献   

6.
根据洮河干流4个水文站1956-2009年的逐月径流量资料,从不均匀性和集中程度等方面分析了径流量年内分配的变化特征,并采用Mann-Kendall非参数检验方法分析了流域月、年径流量变化的趋势性.结果表明:洮河干流径流量在枯水季节和丰水季节相差较大,年内分配极不均匀.从时间上来看,1980年以后各水文站径流量的不均匀性和集中程度有所缓解,径流量的集中期有提前的趋势.从空间上来看,洮河流域下游比上游具有更高的不均匀性和集中度,说明越向下游径流量年内分配越不均匀.另外,不均匀性和集中度的相对变化幅度整体有升高趋势.1980年以后洮河干流各月径流量普遍减小,汛期减少尤为明显,且上游枯水期减少趋势大于下游,下游汛期减少趋势大于上游,春、夏季减少趋势大于秋、冬季.洮河干流径流量的年际变化较为剧烈,1980年以后洮河干流年径流量明显减小,且下游减少趋势大于上游.其中,下巴沟、岷县、李家村、红旗站年径流量分别以每年0.14×108,0.28×108,0.35×108,0.37×108m3的速率递减,递减量分别占多年平均径流量的0.91%,0.84%,0.88%,0.81%.  相似文献   

7.
We established a Juniperus przewalski tree ring width chronology, based on tree ring cores collected from the A’nyêmaqên Mountains. Statistical analysis showed that the chronology was highly correlated with instrumental streamflow records from previous August to current July from the Tangnaihai Station in the upper reaches of the Yellow River, with a correlation coefficient of 0.656. Streamflow for the upper reaches of the Yellow River was reconstructed for the past 1234 years. Low flow periods for the 11-year averaged streamflow reconstruction were definite as lower than mean plus 1 standard deviation, and high flow periods were higher than mean minus 1 standard deviation. Over the past 1234 years, high flows occurred 18 times, and low flows occurred 12 times. The main low flow periods were identified as AD 1140–1156, AD 1295–1309, AD 1473–1500, and AD 1820–1847, and the main high flow periods were identified as AD 846–873, and AD 1375–1400. Extremely low streamflow over the reconstruction period was seen during the late 15th century, coinciding with a widespread drought phenomenon, which took place in the northeastern Tibetan Plateau over the same period. Reconstructed streamflow shows significant low-frequency variability, which is in line with drought variability of neighboring regions, as inferred from tree rings and other proxies. Multi-taper spectral analysis suggests the existence of significant periods of 2–5, 22, 35–38, 55–62, and 114–227 years, particularly significant for cyclic variations of years 159 and 36.  相似文献   

8.
采用遥感监测方法对内蒙古伊敏矿区生态环境进行回顾评价,解译了覆盖矿区的5期(1987年、1991年、1994年、2002年、2004年)Landsat—TM遥感影像,将1987--2004年划分为4个时段,对每个时段的监测区域进行了土地利用变化分析、草地植被覆盖度变化分析、草地产草量与疏干地下水量的相关性分析.以此为基础,对比了疏干降落漏斗影响范围内、外的变化差异.分析了疏干地下水对矿区及其周边草原生态环境的影响.结果表明,煤矿生产对周边草原生态环境的影响不大.  相似文献   

9.
Ostracods are small bivalved aquatic crustaceans. They secrete shells of low-Mg calcite that are often preserved in lake sediments. Recent work has shown that the uptake of trace elements (especially Mg and Sr) into the shell may be a function of the salinity and temperature of the host water. We measured Sr/Ca ratios in living ostracod valves from the species of genus Limnocythere cf. inopinata and Sr2+/Ca2+ ratios of the host water to calculate distribution coefficient of genus Limnocythere cf. inopinata in the Daihai Lake. A function for Sr2+/Ca2+ ratio and salinity was established by measuring a series of Sr2+/Ca2+ ratios and salinities of the lake water in different places of the Daihai Lake. Finally paleosalinities of the lake water were quantitatively reconstructed by the Sr/Ca ratios of ostracod shells of the same species in sediment core of the Daihai Lake.  相似文献   

10.
epartment of Wood Science, University of Hamburg, Hamburg D-21031, GermanyBased on three Chinese pine (Pinus tabulaeformis Carr.) and one Meyer spruce (Picea meyeri Rehd. et Wils.) ring-width chronologies, a 163-year drought history was reconstructed in the eastern Ortindag Sand Land. All tree-ring chronologies show large inter-annual variations and strong common signals and fairly consistent variation between different chronologies, indicating that they are excellent proxy of regional climate. A regional chronology (RC) was established by averaging the four standard chronologies and further employed for the analysis and climatic reconstruction. The analysis revealed that tree growth is primarily limited by low precipitation in February-March and June-July and high temperature in May-July. In addition, RC has high correlations with the monthly Palmer drought severity index (PDSI) prior to and during the growing season because the PDSI considers the accumulation of the droughts. Response function analysis revealed that RC only exhibits significant correlations with the PDSI in June and July (close to the 95% significance level in May). Because May―July is a critical period for tree growth, the average May-July PDSI (PDSI5-7) was reconstructed back to 1842 using RC in the Ortindag Sand Land. The reconstruction can explain 52% of the PDSI variance and the equation was rather stable over time. It agrees well with the variation of the average dryness/wetness indices in North China,and captures the decline process of the East Asian summer monsoon since the mid-1960s. It is worth noting that the Ortindag Sand Land has experienced the most severe drought in the recent 40 years based on the 163-year drought reconstruction. Like summer precipitation in North China the reconstructed PDSI5-7 also displays a 20-year oscillation.  相似文献   

11.
Based on the function relationship between the shell length of Limnocythere inopinata and the salinity of its living water in Tibetan Plateau lakes, the paleosalinty of Qinghai Lake in the past 900 years was reconstructed through the measurement of the adult body length of Limnocythere inopinata. Meanwhile, the paleosalinity sequence of Qinghai Lake during the same period was rebuilt by the St/Ca ratio of the shell of Eucypris inflata combined with the St/Ca ratio of living ostracod valves from the species of genus Eucypris inflata and the host water. The paleosalinity results obtained by two different methods were compared and assessed in this paper. To check the result, it was also contrasted with other historical climatic sequences of this area including tree ring and ice core. It was shown that the paleosalinity sequence rebuilt by adult ostracod body length had high reliability, and the paleosalinity reconstruction method by trace elements of ostracod shells was not suitable for Qinghai Lake. From the reconstructed paleosalinty sequence of Qinghai Lake, it can be found that low salinity during 1160-1290 AD showed the humid climate condition on the Mediaeval Warm Period in this area, while the high salinity during 1410-1540 AD, 1610-1670 AD and 1770-1850 AD which was corresponding to the three cold pulses of the Little Ice Age with a dry climate condition. And the high salinity in the latest several decades was consistent with recent warm and dry trends of the climate in this area. The good consistency of the reconstructed palaeosalinity sequence and the precipitation sequence in this area rebuilt by tree ring proves the reconstruction of past lake salinity is reliable.  相似文献   

12.
内蒙古中部太古界乌拉山岩群变质作用PTt轨迹表现为顺时针形式,峰期变质的温度为830~948℃,压力为0.942GPa.是麻粒岩相变质作用发生于地壳大幅度增厚的环境,强烈的构造变动和区域性高热流共同作用的结果.从第二阶段峰期变质到第三阶段近等温减压过程为区域性地壳减薄的开始,直至第四期角闪岩相的退变质阶段显示出地壳大幅度减薄和抬升剥蚀的特点.  相似文献   

13.
《科学通报(英文版)》1999,44(Z1):205-205
The sediments, at bore-hole T-3 in the upper reaches of the Urumqi River, are 10.7 m thick, and are composed mainly of till, slope-washed materials, solifluction and glacial-water deposits. The borehole can be divided into six sections based on the pollen distribution, magnetic susceptibility , δ~(13)C determinations and the diatoms distribution. There were three cold and dry periods during the past 10.0 Ka (10~3 years): before 9.3 KaBP, from 8.1 to 5.6 KaBP and 3.0 to 1.0 KaBP. The three warmer periods were from 9.3 to 8.1 KaBP, 5.6 to 3.0 KaBP and since 1.0 KaBP. The Holocene maximum was between 5.6 and 3 KaBP. However, the vegetation compositions, mainly C_3 plants, the magnetic susceptibility and the δ~(13)C were little changed in the study region in the past 10 Ka. Indications are that the climate was relatively cold and stable during the past 10 Ka.  相似文献   

14.
采用SWAT模型和RegCM3模式预测A1B情景下黄河源区未来的径流变化趋势。构建了黄河源区SWAT模型,采用2000—2005年和2006—2008年逐日气温、降水、流量等实测水文气象数据对模型进行率定和验证,率定期纳西效率系数为0.86、相关系数为0.83,验证期纳西效率系数为0.89、相关系数为0.86,模拟效果好。评价RegCM3模式对黄河源区气温和降水的模拟能力,结果表明该模式对气温和降水的模拟具有很好的相关性,模拟效果令人满意。采用RegCM3模式预测的A1B情景下未来气候信息经系统校正和插值处理后,驱动所构建的SWAT模型模拟了黄河源区2010—2098年的径流系列,预估了黄河源区未来的径流变化趋势。研究结果表明,黄河源区唐乃亥水文站径流系列在2010—2098年总体上呈减少趋势,在2010—2039年、2040—2069年和2070—2098年3个时期呈减—增—减的交替变化趋势,其中2010—2039年和2040—2069年变化趋势不显著,2070—2098年呈显著减少趋势。  相似文献   

15.
以内蒙古洮儿河流域为研究对象,选取阿尔山气象站、索伦气象站和索伦水文站数据,分析了洮儿河流域累日降水量与索伦水文站流量相关关系,并以累日降水量为主要指标,利用神经网络模型,对流域内重点断面流量进行预测,以期为洮儿河水文站流量预测提供依据。  相似文献   

16.
通过对黄河内蒙河段洪水过程及河床冲淤过程分析,探讨了支流洪水对河段河槽萎缩的影响。  相似文献   

17.
The water shortage problem in the Haihe River Basin is the most severe in China, and has restricted its economic development. Over-extraction of groundwater has been very severe in the past 30 years. To solve this problem, scientific decisions should be made from a historical perspective. It is important to describe water cycle evolution in the Haihe River basin over the past 10000 years. Datasets of paleoclimate, paleogeography, palynoflora, historical record, isotopic abundance ratio and content were collected for research on different time scales. Some interesting conclusions were drawn by a comprehensive analysis method. First, radiation was the intrinsic force driving the evolution of water cycle. Generally, precipitation increased with temperature. Second, precipitation was high during 8 ka-5 ka B.P., the so-called Yangshao warm period of the Middle Holocene, which recharged the major part of the Quaternary groundwater. Third, heavy floods during this period transported sediment to the seaside, forming the Coastal Plain where cities such as Tianjin, Huanghua, Cangzhou are now located. In the last 3000 years, intermittent moderate floods did not have enough energy to transport sediment to the sea. Rivers usually overflowed in the piedmont region of the Taihang Mountains, and sediment deposited there formed the Piedmont Plain, where locate Shijiazhuang, Xingtai, Handan, Baoding and other cities. Precipitation had a high correlation with temperature in Haihe River Basin in the past 10000 years: the high temperature usually coupled with high precipitation. Today precipitation in the Haihe River Basin is relatively low, owing to low temperature. This study reveals the relationship between temperature, precipitation and river networks in the past 10000 years in Haihe River Basin, which has great scientific and practical importance in understanding the current water circulation and water shortage.  相似文献   

18.
近50年渭河关中地区地表径流变化及其归因分析?   总被引:1,自引:0,他引:1  
采用流域水文过程模拟和水文气象统计学相结合的方法,归因分析了近50a来渭河关中地区地表径流的变化.通过对关中地区1958—2008年水文气象要素进行趋势检验分析,发现近50a来该区域地表径流量呈现显著下降趋势,而降雨量和潜在蒸散发量没有明显的变化,说明径流的变化主要受人类活动的影响,并用Mann-Kendall法检验出1990年为径流过程的突变点.基于此,构建SIMHYD月降雨—径流水文模型,以1958—1989年为模拟预处理期,1990—2008年为模拟检测期,通过模拟分析获得气候变化和人类活动对径流影响的归因分析结果.同时采用改进的气候弹性系数法对上述径流变化归因分析进行验证,也得到了近似的结果.结果表明,气候变化对径流减少的影响程度为18%~22%,而人类活动为78%~82%.  相似文献   

19.
对内蒙古科技进步的总体情况进行了扼要的评价,认为内蒙古的经济增长,不仅依赖于企业的技术创新,还依赖于企业的管理和制度等方面的创新。分析了内蒙古企业创新存在的若干障碍,并在此基础上提出了推动内蒙古企业创新的若干建议。  相似文献   

20.
This study surveyed and analyzed the vegetation heterogeneity in the Center of Inner Mongolia (CIM) by a new method based on the beta-binomial distribution for each kind of vegetation. Of the 190 large quadrats of 5 mm × 5 mm (representing an area of 50 km × 50 km) (referred to as L-quadrats hereafter) were extracted from about an area of 475,000 km2. Each L-quadrat was divided into four small quadrats (S-quadrat) of 2.5 mm × 2.5 mm (equivalent to 25 km × 25 km) and the frequency of occurrence of each type of the vegetations was recorded in each small quadrate. The weighted average heterogeneity from all of the vegetations composing a landscape provides a measure at landscape level to determine the spatial intricateness of landscape composition. Our results indicated that each vegetation has its own distribution pattern; and the degree of heterogeneity is different from one kind of vegetation to the other. The results proved that the beta-binomial distribution can be very useful for analyzing vegetation landscapes.  相似文献   

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