An insight into the dynamics of Lake Nainital (Kumaun Himalaya,India) using stable isotope data / Un aperçu de la dynamique du Lac Nainital (Himalaya Kumaun,Inde) à partir de données isotopiques stables     

《水文科学杂志》2013,58(6)

Abstract

Abstract The water balance of Lake Nainital in the Kumaun Himalaya, India was previously computed using water budgeting and other indirect methods. An important data set of stable oxygen and hydrogen isotopic composition of water sources of the lake region was also presented and used to verify the annual estimates of subsurface flow/water balance. In the present study, the same data set has been used to investigate the dynamics of this lake in terms of the seasonal processes operative during the annual hydrological cycle: increased inflow during the monsoon, delayed groundwater inflow, and stratification and mixing of water. Based on the available data, a simple two-box model was used to constrain the values of exchange coefficients between the hypolimnion and epilimnion layers and to estimate evaporation and outflow components from the isotopic data.  相似文献   

基于PCRaster的流域非点源氮磷负荷估算   总被引：4，自引：0，他引：4       下载免费PDF全文

赵广举  田鹏  穆兴民  高俊峰  李恒鹏  张增信 《水科学进展》2012,23(1):80-86

以太湖流域上游的西笤溪流域为研究区,应用动态环境模拟语言PCRaster构建月水文和氮磷营养物质输出模型,分析流域内氮磷输出的时空分布特征。以输出系数法为基础,将分布式水文模型与非点源负荷模型相结合,应用地理信息技术构建基于栅格的非点源污染模拟模型,根据1988~2007年的水文、水质实测数据对模型进行率定和验证,定量分析西笤溪流域非点源污染负荷量与氮磷输出的空间分布。研究结果显示:基于单元网格的月水文模型在该流域具有较好的应用效果,率定和验证期的Nash系数和线性相关系数R2均超过了0.80。应用模型估算西笤溪流域非点源污染2002~2005年总氮年输出量为1 670~2 035t/a,2002~2007年总磷输出量为102~164t/a。氮磷负荷的空间分布表明以稻麦或水稻/油菜轮作的农田是非点源污染的最主要来源。  相似文献   

伽马能谱法测量水中226Ra最短平衡时间的确定          下载免费PDF全文

曹诚彦  徐步新  陈美芳 《江苏地质》2012,36(2):219-221

伽马(γ)能谱法测量水中226Ra,在制样过程中天然放射性核素衰变链遭到破坏,一般规定样品放射性平衡期为3～4周后测定。通过试验证明,样品天然放射性核素衰变链最终达到平衡的最短时间为11d,测量结果在允许误差范围内,满足测量精度。  相似文献   

岷江犍为水电站库区右岸塘坝煤矿涌水量研究     

袁婷  邓英尔  蒋欢欢 《地下水》2012,(1):12-13,79

在大型矿山开采工程中,涌水量往往会影响生产和工程的进度,而且会威胁矿山开采安全。塘坝煤矿位于岷江犍为水电站库区右岸。分析了塘坝煤矿矿区的水文地质条件,分别采用了地下水动力学解析公式与水均衡法,计算了塘坝煤矿目前开采区的涌水量,并对三种计算方法进行了比较,结合井田实际水文地质条件及相关分析,得出了塘坝煤矿目前开采区比较符合实际的涌水量,即水平廊道法结果比较接近实际情况,为煤矿的安全开采提供了相关的依据。  相似文献   

九寨沟地下径流系统     

杨俊义  张慧利 《四川地质学报》2012,32(1):80-82,93

九寨沟景观钙华呈相对集中的带状分布,地表径流多处流量呈现异常,运用水均衡原理,论证了九寨沟次级含水单元间的补、排关系,用则查哇沟、丹祖沟次级含水单元通过渗漏补给日则沟,保证了九寨沟核心景观的稳定,长海对九寨沟径流系统具有重要调节作用。  相似文献   

一种改进的简单的估算原始岩浆的方法   总被引：2，自引：0，他引：2  

李永生  张招崇  聂保锋 《地质论评》2012,58(4):653-659

利用橄榄石和熔浆的Fe—Mg分配系数,制作了MgO—FeO演化图解。根据MgO—FeO体系中Fo橄榄石的Fo值:Fo=n(Mg)÷n(Mg)+n(Fen(Mg)/n(Mg)+n(Fe))等值线与Fe—Mg演化曲线交点确定原始岩浆成分。该图解优点在于可以更简单、直观地判别原始岩浆成分,适用于橄榄石分离结晶体系。同时介绍了该图解的使用方法,并以峨眉山大火成岩省丽江地区的大具与仕满两个剖面的苦橄岩为例,说明如何应用该图解来恢复原始岩浆以及解释岩石的成因。研究结果表明,仕满地区原始岩浆MgO、FeO含量分别为23.5%和12.8%,部分熔融程度较高,SM-14和SM-15是由仕满原始岩浆经过轻度橄榄石分离结晶形成的,基本可以代表原始岩浆成分。大具地区原始岩浆可分为两类,一类部分熔融程度较低,MgO、FeO含量分别为19.8%和11.3%;另一类部分熔融程度较高,MgO、FeO含量分别为23%和13.3%,与仕满原始岩浆成分类似。大具地区的岩石样品成分均不能代表该地区的原始岩浆成分,而是经历了明显的橄榄石分离结晶作用。另外,峨眉山大火成岩省中绝大多数的玄武岩中CaO含量不符合橄榄石分离结晶关系,并且MgO含量一般都低于8%,以及岩石中普遍出现单斜辉石和斜长石矿物等都表明这些玄武岩不可能由地幔部分熔融形成的原始岩浆直接通过橄榄石分离结晶作用形成。  相似文献   

A 40,000-yr record of environmental change from Burial Lake in Northwest Alaska     

Mark B. Abbott  Mary E. Edwards  Bruce P. Finney 《Quaternary Research》2010,74(1):156-165

Burial Lake in northwest Alaska records changes in water level and regional vegetation since ∼ 39,000 cal yr BP based on terrestrial macrofossil AMS radiocarbon dates. A sedimentary unconformity is dated between 34,800 and 23,200 cal yr BP. During all or some of this period there was a hiatus in deposition indicating a major drop in lake level and deflation of lacustrine sediments. MIS 3 vegetation was herb-shrub tundra; more xeric graminoid-herb tundra developed after 23,200 cal yr BP. The tundra gradually became more mesic after 17,000 cal yr BP. Expansions of Salix then Betula, at 15,000 and 14,000 cal yr BP, respectively, are coincident with a major rise in lake level marked by increasing fine-grained sediment and higher organic matter content. Several sites in the region display disrupted sedimentation and probable hiatuses during the last glacial maximum (LGM); together regional data indicate an arid interval prior to and during the LGM and continued low moisture levels until ∼ 15,000 cal yr BP. AMS ¹⁴C dates from Burial Lake are approximately synchronous with AMS ¹⁴C dates reported for the Betula expansion at nearby sites and sites across northern Alaska, but 1000-2000 yr younger than bulk-sediment dates.  相似文献   

Geotechnical Characteristics of Volcanic Soils Taken from Recent Eruptions     

Rolando P. Orense  Andrew Zapanta Jr.  Akinori Hata  Ikuo Towhata 《Geotechnical and Geological Engineering》2006,24(1):129-161

Recent volcanic eruptions at Mt. Unzen (Japan) in 1990 and Mt. Pinatubo (Philippines) in 1991 produced voluminous amounts of ash and sediments which inundated widespread areas. In later rehabilitation and reconstruction, it is practical and economical to use these freshly deposited sediments as materials for foundations and embankments. However, the geotechnical properties of young volcanic products have not been fully investigated. Accordingly, we investigated the geotechnical characteristics of volcanic soils associated with three recent eruptions, namely, the Unzen and Izu-Oshima eruptions of 1990 and 1986, respectively, in Japan and the Pinatubo eruption of 1991 in the Philippines. We specifically investigated index properties, permeability and compaction characteristics, and strength and deformation behavior in drained conditions. Additionally, we examined the dynamic properties and liquefaction characteristics of samples taken from Mt. Pinatubo. The results showed that the geotechnical characteristics of the deposits generally varied with the sampling sites. Depending on the location, either upstream or downstream from a volcano, the preferential sizing due to alluvial deposition affects engineering properties of the deposits. For example, volcanic sediments upstream from Mt. Pinatubo have high compressibility and low cyclic strength, whereas those taken downstream show dilative tendencies and high liquefaction strength.  相似文献   

人口总量及其空间分布特征与经济发展关系的动力学研究   总被引：5，自引：3，他引：2  

陈楠  林宗坚 《测绘科学》2006,31(4):14-16

建立了人口—经济系统的微分方程组模型,并在方程中引入人口空间分布与经济发展协调的因子η,通过分析模型的稳定性特征得出以下结论:人口经济系统是复杂的非线性关系;人口的过于快速增长会使经济总量趋向于零;如果η>1并且较高,则人口经济系统发展稳定时,经济总量会高些,也即人口数量稳定在同样水平时,会因为空间分布的不同而有不同的经济产出。说明在控制人口数量的同时必须重视人口空间分布的问题。  相似文献   

区域蒸散发量的遥感模型方法研究   总被引：5，自引：0，他引：5  

乔平林  张继贤  王翠华  燕琴  刘正军 《测绘科学》2006,31(3):45-46,61

蒸散是水资源管理的一个重要参数。与传统的蒸散计算方法相比,利用遥感进行蒸散研究具有快速、准确、大区域尺度及地图可视化显示等特点。本文通过研究,提出了基于能量平衡方法遥感反演蒸散发的计算模型,指出了模型参数的求解方法,建立了基于MOD IS遥感数据的大区域蒸散发遥感反演技术方法。通过对石羊河流域进行试验,反演误差基本小于10%,并且具有进一步推广的技术前景。  相似文献