Long-term temperature variability has significant effects on runoff into the upper reaches of inland rivers. This paper developed a tree-ring chronology of Qilian juniper (Sabina przewalskii Kom.) from the upper tree-...Long-term temperature variability has significant effects on runoff into the upper reaches of inland rivers. This paper developed a tree-ring chronology of Qilian juniper (Sabina przewalskii Kom.) from the upper tree-line of the middle Qilian Mountains within the upper reaches of Heihe River Basin, Northwest China for a long-term reconstruction of temperature at the study site. In this paper, tree-ring chronology was used to examine climate-growth associations considering local climate data obtained from Qilian Meteorological Station. The results showed that temperatures correlated extremely well with standardized growth indices of trees (r=0.564, P<0.001). Tree-ring chronology was highest correlated with annual mean temperature (r=0.641, P<0.0001). Annual mean temperature which spans the period of 1445–2011 was reconstructed and explained 57.8% of the inter-annual to decadal temperature variance at the regional scale for the period 1961–2011. Spatial correlation patterns revealed that reconstructed temperature data and gridded temperature data had a significant correlation on a regional scale, indicating that the reconstruction represents climatic variations for an extended area surrounding the sampling sites. Analysis of the temperature reconstruction indicated that major cold periods occurred during the periods of 1450s–1480s, 1590s–1770s, 1810s–1890s, 1920s–1940s, and 1960s–1970s. Warm intervals occurred during 1490s–1580s, 1780s–1800s, 1900s–1910s, 1950s, and 1980s to present. The coldest 100-year and decadal periods occurred from 1490s–1580s and 1780s–1800s, respectively, while the warmest 100 years within the studied time period was the 20<sup>th</sup> century. Colder events and intervals coincided with wet or moist conditions in and near the study region. The reconstructed temperature agreed well with other temperature series reconstructed across the surrounding areas, demonstrating that this reconstructed temperature could be used to evaluate regional climate change. Compared to the tree-ring reconstructed temperature from nearby regions and records of glacier fluctuations from the surrounding high mountains, this reconstruction was reliable, and could aid in the evaluation of regional climate variability. Spectral analyses suggested that the reconstructed annual mean temperature variation may be related to large-scale atmospheric–oceanic variability such as the solar activity, Pacific Decadal Oscillation (PDO) and El Ni?o–Southern Oscillation (ENSO).展开更多
Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using fie...Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.展开更多
Palaeoflood hydrology study is a leading subject in global change study. Through field investigation in the upper reaches of Hanjiang River, palaeoflood slackwater deposits （SWD） were found in the bedrock gorges of ...Palaeoflood hydrology study is a leading subject in global change study. Through field investigation in the upper reaches of Hanjiang River, palaeoflood slackwater deposits （SWD） were found in the bedrock gorges of the Yunxi reach. The results of field observation, laboratory analysis including particle-size distribution and magnetic susceptibility, and com- parison with modern flood deposits, the SWD were identified as the most typical Holocene palaeoflood deposits of the Hanjiang River. By using stratig;aphic correlation and OSL dating method, the palaeoflood event was dated to be 3200-2800 a BP at the turn from the middle to late Holocene. According to the palaeoflood peak stage and hydraulic parameters, the peak discharges of the palaeoflood were reconstructed as 48,830-51,710 m3/s by using the slope-area method. At same time, the flood peak discharges of 1983, 2005 and 2010 severe floods were reconstructed with the same method and hydraulic parameters in the same cross section. The error between the reconstructed and gauged discharges was 1.99%-4.21%. This showed that the reconstructed palaeoflood peak discharges were reliable. The flood peak discharge-frequency relationship at 10,000-year time scale was established by a com- bination of the gauged flood, historical flood and palaeoflood hydrological data. These results are very important for hydraulic engineering and flood mitigation on the Hanjiang River.展开更多
本研究以太湖上游平原圩区为研究对象,采用氮动态模型(Nitrogen dynamic model for lowland polder systems,NDP)和磷动态模型(Phosphorus dynamic model for lowland polder systems,PDP)模拟圩区氮磷流失的动态过程,并基于圩区氮磷流...本研究以太湖上游平原圩区为研究对象,采用氮动态模型(Nitrogen dynamic model for lowland polder systems,NDP)和磷动态模型(Phosphorus dynamic model for lowland polder systems,PDP)模拟圩区氮磷流失的动态过程,并基于圩区氮磷流失机制进行管理情景定量模拟与氮磷减污效益分析。结果表明:①圩区氮磷的年平均流失强度分别为40和1.75 kg/(hm^(2)·a),高于太湖流域的平均氮磷流失水平;②当圩区外部水质控制为Ⅳ类时,氮磷流失强度分别为37.54和1.58 kg/(hm^(2)·a),圩区截流氮磷量分别增加4.9%和9.9%,高氮磷流失级别的圩区数量分别减少26.2%和63.8%;③如将圩区内5%的水田转化为水体,氮磷流失强度分别为36.73和1.72 kg/(hm^(2)·a),圩区截流氮磷量分别增加6.6%和1.7%,高氮磷流失级别的圩区数量分别减少46.2%和22.5%;④圩区氮磷的流失机制具有明显不同,圩外水质目标对于圩内磷的流失影响较大,圩内的水体和坑塘等对于氮滞留和净化更加有优势。展开更多
基金supported by the National Natural Science Foundation of China(91025002,30970492)the National Key Technology Research&Development Program(2012BAC08B05)the Key Project of the Chinese Academy of Sciences(KZZD-EW-04-05)
文摘Long-term temperature variability has significant effects on runoff into the upper reaches of inland rivers. This paper developed a tree-ring chronology of Qilian juniper (Sabina przewalskii Kom.) from the upper tree-line of the middle Qilian Mountains within the upper reaches of Heihe River Basin, Northwest China for a long-term reconstruction of temperature at the study site. In this paper, tree-ring chronology was used to examine climate-growth associations considering local climate data obtained from Qilian Meteorological Station. The results showed that temperatures correlated extremely well with standardized growth indices of trees (r=0.564, P<0.001). Tree-ring chronology was highest correlated with annual mean temperature (r=0.641, P<0.0001). Annual mean temperature which spans the period of 1445–2011 was reconstructed and explained 57.8% of the inter-annual to decadal temperature variance at the regional scale for the period 1961–2011. Spatial correlation patterns revealed that reconstructed temperature data and gridded temperature data had a significant correlation on a regional scale, indicating that the reconstruction represents climatic variations for an extended area surrounding the sampling sites. Analysis of the temperature reconstruction indicated that major cold periods occurred during the periods of 1450s–1480s, 1590s–1770s, 1810s–1890s, 1920s–1940s, and 1960s–1970s. Warm intervals occurred during 1490s–1580s, 1780s–1800s, 1900s–1910s, 1950s, and 1980s to present. The coldest 100-year and decadal periods occurred from 1490s–1580s and 1780s–1800s, respectively, while the warmest 100 years within the studied time period was the 20<sup>th</sup> century. Colder events and intervals coincided with wet or moist conditions in and near the study region. The reconstructed temperature agreed well with other temperature series reconstructed across the surrounding areas, demonstrating that this reconstructed temperature could be used to evaluate regional climate change. Compared to the tree-ring reconstructed temperature from nearby regions and records of glacier fluctuations from the surrounding high mountains, this reconstruction was reliable, and could aid in the evaluation of regional climate variability. Spectral analyses suggested that the reconstructed annual mean temperature variation may be related to large-scale atmospheric–oceanic variability such as the solar activity, Pacific Decadal Oscillation (PDO) and El Ni?o–Southern Oscillation (ENSO).
基金financially supported by the National Nature Science Foundation of China under Grant No.41372333,41172158China Geological Survey(grant No.1212011220123)
文摘Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.
基金Foundation： National Natural Science Foundation of China, No.41030637, No.41271108 Ph.D. Programs Foundation from Ministry of Education of China, No.20110202130002
文摘Palaeoflood hydrology study is a leading subject in global change study. Through field investigation in the upper reaches of Hanjiang River, palaeoflood slackwater deposits （SWD） were found in the bedrock gorges of the Yunxi reach. The results of field observation, laboratory analysis including particle-size distribution and magnetic susceptibility, and com- parison with modern flood deposits, the SWD were identified as the most typical Holocene palaeoflood deposits of the Hanjiang River. By using stratig;aphic correlation and OSL dating method, the palaeoflood event was dated to be 3200-2800 a BP at the turn from the middle to late Holocene. According to the palaeoflood peak stage and hydraulic parameters, the peak discharges of the palaeoflood were reconstructed as 48,830-51,710 m3/s by using the slope-area method. At same time, the flood peak discharges of 1983, 2005 and 2010 severe floods were reconstructed with the same method and hydraulic parameters in the same cross section. The error between the reconstructed and gauged discharges was 1.99%-4.21%. This showed that the reconstructed palaeoflood peak discharges were reliable. The flood peak discharge-frequency relationship at 10,000-year time scale was established by a com- bination of the gauged flood, historical flood and palaeoflood hydrological data. These results are very important for hydraulic engineering and flood mitigation on the Hanjiang River.
文摘本研究以太湖上游平原圩区为研究对象,采用氮动态模型(Nitrogen dynamic model for lowland polder systems,NDP)和磷动态模型(Phosphorus dynamic model for lowland polder systems,PDP)模拟圩区氮磷流失的动态过程,并基于圩区氮磷流失机制进行管理情景定量模拟与氮磷减污效益分析。结果表明:①圩区氮磷的年平均流失强度分别为40和1.75 kg/(hm^(2)·a),高于太湖流域的平均氮磷流失水平;②当圩区外部水质控制为Ⅳ类时,氮磷流失强度分别为37.54和1.58 kg/(hm^(2)·a),圩区截流氮磷量分别增加4.9%和9.9%,高氮磷流失级别的圩区数量分别减少26.2%和63.8%;③如将圩区内5%的水田转化为水体,氮磷流失强度分别为36.73和1.72 kg/(hm^(2)·a),圩区截流氮磷量分别增加6.6%和1.7%,高氮磷流失级别的圩区数量分别减少46.2%和22.5%;④圩区氮磷的流失机制具有明显不同,圩外水质目标对于圩内磷的流失影响较大,圩内的水体和坑塘等对于氮滞留和净化更加有优势。
