甘肃西北部黑河流域水资源对下游生态环境变化的影响阈   总被引：3，自引：0，他引：3  

张光辉聂振龙  刘少玉王金哲 《地质通报》2006,25(1):244-250

从流域尺度水资源承载能力及其有限性、可变性和上下游关联性的角度,探讨了黑河流域下游区生态环境变化的影响阈,阐明了不同水文年中游区的安全引水量和不同目标下下游区的生态环境修复对水资源的需求阈.基于多年平均地表径流量37.8×108m3/a的安全引水量为13.97×108m3/a和枯水年份(95%保证率)的安全引水量为10.14×108m3/a,下游区初步改善生态环境的生态需水量为8.01×108m3/a.提出了中游区经济社会可持续发展的水资源保障阈,即未来20年生产生活安全需水量介于22×108～23×108m3/a之间.在此基础上,阐明了在中游区经济社会稳定持续发展目标约束下确保黑河流域下游区生态环境不断改善的流域水资源优化配置模式及对策.  相似文献   

基于SuperMap的松花江流域地理信息系统   总被引：3，自引：0，他引：3  

康国婷  陈圣波  谭瑶 《吉林地质》2006,25(3):64-68

松花江流域地理信息系统利用地理信息系统技术,以组件式GIS-SuperMap为基础,对松花江全流域空间信息进行管理,不仅实现了松花江全流域的污染模拟分析功能,还融合遥感影像、数字高程模型,实现了松花江全流域三维动态模拟功能.松花江流域地理信息系统的开发,对于实现水资源的可持续开发利用和流域的可持续发展具有重要意义.  相似文献   

珠江口盆地沉降史定量模拟和分析   总被引：3，自引：0，他引：3  

高红芳杜德莉  钟广见 《南海地质研究》2006,(1):11-20

运用Petrosys盆地模拟系统，定量和动态地模拟了珠江口盆地三个主要坳陷的沉降过程，论述了沉降速率的变化与生储盖发育之间的关联，认为珠江口盆地构造沉降史具有幕式、多阶段变化的特征。盆地第一幕和第二幕沉降是盆地发育的主要时期，奠定了盆地的构造格架，形成了盆地主要的沉积地层和油气资源。第三幕沉降为盆地的改造和完成阶段，是盆地区域盖层发育的主要时期。  相似文献   

GRAPES模式对长江流域天气预报的检验分析   总被引：1，自引：3，他引：1  

徐双柱  张兵  谌伟 《气象》2007,33(11):65-71

GRAPES是中国新一代数值天气预报模式。使用GRAPES中尺度模式产品和常规观测资料,分析检验了2005、2006年汛期发生在长江流域的11次主要降水天气过程,得到:GRAPES模式对于长江流域的预报,无论是降水、天气形势还是物理量都有比较强的预报能力;GRAPES模式对级别较大的降水预报容易出现漏报,而不易出现空报,对于10mm以下的雨区预报比较准确,而对于大于50mm的雨区预报,尤其是大于100mm的降水中心存在较大的偏差;对于西太平洋副热带高压的预报比实际情况偏南、偏东;对于水汽通量散度的预报与实际情况比较吻合。  相似文献   

Climatic change during the last 4000 years in the southern Tarim Basin,Xinjiang, northwest China   总被引：1，自引：0，他引：1  

Wei Zhong  Ji Bin Xue  Qiang Shu  Li Guo Wang 《第四纪科学杂志》2007,22(7):659-665

In this study, a ca. 4000 cal. yr ancient lacustrine (or wetland) sediment record at the southern margin of Tarim Basin is used to reconstruct the history of climate change. Six radiocarbon dates on organic matter were obtained. δ¹⁸O and δ¹³C of carbonate, pollen and sediment particle size were analysed for climate proxies. The proxies indicate that a drier climate prevailed in the area before ca. 1010 BC and during period 1010 BC–AD 500 climate then changed rapidly and continuously from dry to moist, but after about AD 500 climate generally shows dry condition. Several centennial‐scale climatic events were revealed, with the wettest spell during AD 450–550, and a relatively wetter interval between AD 930–1030. Pollen results show that regional climate may influence human agricultural activities. Spectral analysis of mean grain size (MGS) proxy reveals statistically pronounced cyclic signals, such as ca. 200 yr, ca. 120 yr, ca. 90 yr, ca. 45 yr and ca. 33 or 30 yr, which may be associated with solar activities, implying that solar variability plays an important role in the decadal‐ and centennial‐scale climate variations in the study area. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

The Holocene estuarine sequence at Redwick, Welsh Severn Estuary Levels, UK: the character and role of silts     

J.R.L. Allen 《Proceedings of the Geologists' Association. Geologists' Association》2007,118(2):157-174

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Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River: Relative importance of changes in bed-sand grain size and bed-sand area     

D.J. Topping  D.M. Rubin 《Sedimentary Geology》2007,202(3):538-561

Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Construction and operation of the dam has enhanced the degree to which the first two of these four effects are evident, and has not affected the degree to which the last two effects of sand supply limitation are evident in the Colorado River in Marble and Grand canyons. The first three of the effects involve coupled changes in suspended-sand concentration and grain size that are controlled by changes in the upstream supply of sand. During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase, even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. Also associated with these changes in sand supply are changes in the fraction of the bed that is covered by sand. Thus, suspended-sand concentration in the Colorado River is likely regulated by both changes in the bed-sand grain size and changes in the bed-sand area. A physically based flow and suspended-sediment transport model is developed, tested, and applied to data from the Colorado River to evaluate the relative importance of changes in the bed-sand grain size and changes in the bed-sand area in regulating suspended-sand concentration. Although the model was developed using approximations for steady, uniform flow, and other simplifications that are not met in the Colorado River, the results nevertheless support the idea that changes in bed-sand grain size are much more important than changes in bed-sand area in regulating the concentration of suspended sand.  相似文献   

珠江口咸潮入侵分析与经验模型——以磨刀门水道为例   总被引：8，自引：0，他引：8       下载免费PDF全文

陈水森  方立刚  李宏丽  张立新 《水科学进展》2007,18(5):751-755

收集了2004-2006年珠江口磨刀门水道咸潮发生时测站(1~7)逐日定时观测的的含氯度、水位与流量数据,分析了各监测站含氯度与水位的日变化与年变化,导出了咸潮演变各过程中,含氯度与径流、潮流、河口地形等的关系式,建立了珠江口地区磨刀门水道咸潮入侵的经验模型。据此,模拟了2006年1月12日的磨刀门地区的咸潮入侵态势,经过和沿途各观测点验证发现与实测数据非常吻合。以含氯度等于250mg/L(饮用水的含氯度最大值)的点作为咸潮入侵的最远点,用简化修改后的盐度模拟模型计算了磨刀门咸潮入侵最大距离,并根据2006年1月12~20日的河口含氯度与最近的上游天河站的径流量实测数据计算出相应的咸潮入侵最大距离。研究表明,在河流枯水期(珠江河口通常是12月至翌年3月),只要获得当天河口的含氯度和上游测站的径流量数据,就能利用此经验模型估算出河流各点的含氯度,作出盐度模拟图,并估算出相应的咸潮入侵最大距离。  相似文献   

Pleistocene tectonics inferred from fluvial terraces of the northern Upper Rhine Graben, Germany   总被引：1，自引：0，他引：1  

Gwendolyn Peters  Ronald T. van Balen 《Tectonophysics》2007,430(1-4):41-65

This study of fluvial terraces of the River Rhine and tributaries aims to search for indications of Pleistocene tectonic activity. The study area includes the northern Upper Rhine Graben (URG), the Mainz Basin and the adjacent Rhenish Massif with the Middle Rhine Valley. High rates of Quaternary surface processes, large amount of human modifications, relatively slow tectonic deformation and presently low intra-plate seismic activity characterize this area. Therefore, the records of relatively slow tectonic deformation are less well preserved and thus difficult to detect. This study uses the relative position of fluvial terraces to determine the more local effects of fault movements on the terraces and to evaluate their displacement rates and patterns. The research is based on a review of previous terrace studies and new terrace mapping from the eastern Mainz Basin and the bordering URG using topographic map interpretations and field observations. This newly mapped sequence of terrace surfaces can be correlated to other terraces in the vicinity on the basis of relative height levels. Terrace correlation between the western Mainz Basin and Middle Rhine Valley relies on a single chronostratigraphic unit (Mosbach sands) and additional relative height correlations. This is the first study to present a continuous correlation of terraces from the western margin of the URG to the Rhenish Massif and enables the study of the transition from the subsiding graben to the uplifted Rhenish Massif. By means of a longitudinal profile, which ranges from the URG to the Rhenish Massif, the influence of individual fault movements on the terrace levels and the large-scale regional uplift is demonstrated. It is evident from the profile that the uplift of Early to Middle Pleistocene terraces increases northwards, towards the Rhenish Massif. The uplift was diachronic, with a significant pulse occurring first in the northern URG (Lower Pleistocene) and later in the Rhenish Massif (Middle Pleistocene). The largest vertical displacements are recorded for the boundary fault separating the Mainz Basin and the Rhenish Massif (Hunsrück–Taunus Boundary Fault) and for faults bounding the northeastern Mainz Basin. The motions and displacement rates calculated for individual faults indicate deformation rates in the order of 0.01–0.08 mm/year. At this stage, the calculation of displacement rates depends mostly on a single dated stratigraphic unit. Additional dating of terrace deposits is urgently needed to better constrain the temporal development of the terrace sequence and the impact of tectonic movements.  相似文献   

氮氧同位素在河流硝酸盐研究中的应用   总被引：9，自引：0，他引：9  

陈法锦  李学辉  贾国东 《地球科学进展》2007,23(12):1251-1257

多年来，世界各地河流普遍存在硝酸盐污染问题。为控制河流的硝酸盐污染，确定河水中硝酸盐的来源以及研究氮的循环过程就显得尤为重要。由于在不同成因下，硝酸盐的δ¹⁵N和δ¹⁸O存在着较大差异，因此利用氮、氧同位素方法研究河流硝酸盐问题正日益受到国内外研究人员的重视。综述了用硝酸盐中氮、氧同位素来研究河流硝酸盐的不同来源(大气沉降、化肥、牲畜粪、土壤硝酸盐等)和示踪其地球化学循环过程，特别是反硝化过程，这两方面的研究进展，并对我国河流硝酸盐研究现状进行了讨论及提出今后的研究方向。   相似文献