浙江晚泥盆世五通组中的楔叶类(Sphenophyllales)化石     

陈其奭 《浙江国土资源》2001,17(1):19-26

本文描述了产自浙江长兴泗安五通组中的几种楔叶类化石Eviostachya hoegii(Stockmans)、Arch-aeocalamites sp.、Hamatophyton verticillatum Gu et Zhi、Sphenophyllum pseudotenerrimum(Sze)和Sphenophyllostachys sp.等.特别是Eviostachya hoegii的发现,为浙江晚泥盆世地层进行国际性对比,提供了新的依据.  相似文献   

Growing season evapotranspiration from Tamarix ramosissima stands under extreme arid conditions in northwest China   总被引：1，自引：0，他引：1  

J. H. Si  Q. Feng  X. Y. Zhang  W. Liu  Y. H. Su  Y. W. Zhang 《Environmental Geology》2005,48(7):861-870

Given the increasing threat of water shortages in the extremely arid regions (rainfall<50 mm year⁻¹) of northwestern China, growing season evapotranspiration (ET) associated with native species such as Tamarix ramosissima is of particular interest. Consequently, this study sought to evaluate the accuracy of daily ET estimates using Bowen ratio data, as well as measuring seasonal ET and development of an energy balance for a stand of T. ramosissima. Bowen ratio apparatus measurements of ET were carried out on a stand of T. ramosissima in a 2.04 km² field, which are all covered with T. ramosissima near Erdaoqiao, Ejina Province, Inner Mongolia Autonomous Region, China. Soil moisture content and green area index were also monitored. Daily ET could be accurately estimated from Bowen ratio data on a continuous basis over the 153-day growing season. The mean daily T. ramosissima ET over this period was 1.62 mm day⁻¹, for a seasonal total of 248.20 mm. In this extremely arid locale, the great majority of available energy dissipated over the growing season was a result of sensible rather than latent heat fluxes. While the heat storage term was the main source of energy at night and a considerable sink of energy during the daytime, the magnitude of the daily mean soil heat flux was small. Such a determination of temporal and ecosystem-specific ET patterns allows an improved prediction of ET in the desert riparian zone.  相似文献   

A New Computer Program for Pile Capacity Prediction using CPT Data     

J. R. Omer  R. Delpak  R. B. Robinson 《Geotechnical and Geological Engineering》2006,24(2):399-426

An interactive computer program “GLAMCPT” is developed for application in soil profiling and prediction of pile load capacity using cone penetration test (CPT) and laboratory soil test results. GLAMCPT calculates pile capacity according to 10 selected methods from European design codes, refereed international publications and recommendations of professional institutions. To demonstrate the capabilities of the program, a database of comprehensive ground investigation and full-scale pile tests in sand, at a Belgian site, is analysed using GLAMCPT. The database comprises 11 static tests and 12 dynamic tests on piles of different construction techniques, including driven pre-cast concrete piles and screwed cast in-situ piles, installed using 5 different procedures. Prior to pile installation, CPTs were carried out at each proposed pile location. Comparison of GLAMCPT predictions with the observed pile capacities reveals that the most accurate of the existing methods yields an average, μ, of predicted to observed pile head capacity [P_uh(p)/P_uh(m)] equal to 0.94. The most consistent method produces a coeffcient of variation (COV) of [P_uh(p)/P_uh(m)] equal to 0.1 and ranking index (RI) of 0.08. Parametric studies have been carried out using GLAMCPT to formulate an improved predictive method, which yielded: μ = 0.99, COV = 0.07 and RI = 0.04.  相似文献   

烟台市海水入侵程度及影响因素探讨   总被引：3，自引：0，他引：3  

姚普  姜振泉  田梅青 《江苏地质》2006,30(2):120-125

介绍了烟台市开发区夹河地区20年来海水入侵的现状及过程。基于区内4个监测井点的长期观测资料,讨论了影响海水入侵程度的主要因素,认为烟台市海水入侵程度与区内地下水动态关联密切。在海侵区内,地下水被海水浸染的程度主要受地下水位降深控制,地下水降落漏斗范围内海水对地下水浸染程度随水位下降逐年加剧,而漏斗区外地下水质则多年保持相对稳定。  相似文献   

METEOROLOGICAL CONDITIONS DURING SLUSH-FLOW RELEASE AND THEIR GEOMORPHOLOGICAL IMPACT IN NORTHWESTERN ICELAND: A CASE STUDY FROM THE BÍLDUDALUR VALLEY     

ARMELLE DECAULNE  ÞORSTEINN SÆMUNDSSON 《Geografiska Annaler: Series A, Physical Geography》2006,88(3):187-197

ABSTRACT. This paper examines triggering factors and geomorphic significance of slush flows in the Bíldudalur valley, northwestern Iceland. The area is prone to release slush flows from two confined gullies, and at least ten flows have been reported since the beginning of the twentieth century. Despite their short path (600 m) and their moderate magnitude (from 6000 to 8000 m³), slush flows in the Bíldudalur valley represent a serious threat for the local community that is situated within the runout and deposition zones. With the help of meteorological data, the release of known slush flows is examined, highlighting the role of heavy rainfall and rapid snow-melt during winter cyclonic activity. The geomorphological impact of slush flows is assessed through the characteristics of the landforms produced during the 1997 and 1998 slush-flow events. It appears that the most obvious characteristics of slush flows in the Bíldudalur valley are the entrainment and deposition of debris, spatially differentiated. Chaotic sedimentation occurs chiefly in the middle part of a clearly concave cone, even if the flows continue beyond the cone.  相似文献   

基于锥形模型的空间方向查询研究     

夏宇  朱欣焰  苏科华 《地理空间信息》2007,5(3):65-67

分析了基于锥形模型进行空间方向查询的原理,提出应结合不同实际应用领域和针对不同的空间数据特征选择适当的空间方向关系形式化描述模型的思想。按照这种思想,针对全国各省1∶25万县市级行政区划数据,设计并实现了基于八方向锥形模型的空间方向查询,取得了比较好的检索效果。  相似文献   

沙地柠条(Caragana)灌丛微生境节肢动物群落特征     

刘任涛  郗伟华  刘佳楠  赵娟  常海涛 《中国沙漠》2018,38(1):117-125

以宁夏荒漠草原柠条（Caragana）灌丛林地为研究对象,于2011年春、夏、秋季,利用陷阱诱捕法,调查了灌丛微生境节肢动物群落分布特征。结果表明：（1）调查共获得节肢动物9目31科32个类群,分属于4种功能群（植食性、捕食性、腐食性和杂食性）。其中,优势类群为蚁科（Formicidae）和拟步甲科（Tenebrionidae）,个体数占总个体数的71.97%;常见类群有7科8个类群,个体数占总个体数的19.72%;其余22个类群为稀有类群,个体数仅占总个体数的8.30%。（2）随着季节变化,灌丛内外节肢动物类群组成和个体数分布均发生改变。春季灌丛内外均包括优势类群、常见类群和稀有类群;夏季灌丛内外均包括优势类群,而灌丛下仅有常见类群,无稀有类群,灌丛外既没有常见类群也没有稀有类群;秋季灌丛内外均有优势类群和常见类群,但灌丛内外均无稀有类群。（3）夏季灌丛内外共有类群数最少,相似性指数最低,秋季次之,而春季灌丛内外共有类群数最多,相似性指数也最高。（4）春季和秋季,灌丛内外微生境中节肢动物个体数、丰富度和Shannon指数均无显著差异（P>0.05）。夏季,节肢动物个体数灌丛内外无显著差异性（P>0.05）,但丰富度和Shannon指数均表现为灌丛内显著高于灌丛外（P<0.05）。（5）春季灌丛内外捕食性、植食性和杂食性节肢动物的个体数和丰富度均无显著差异性（P>0.05）;但是,腐食性动物个体数和丰富度均表现为灌丛内显著高于灌丛外（P<0.05）。夏季,仅有捕食性动物丰富度呈现出灌丛内显著高于灌丛外（P<0.05）,而其他指标灌丛内外均无显著差异性（P>0.05）。秋季,每种功能群动物的个体数和丰富度灌丛内外均无显著差异性（P>0.05）。沙地灌丛内外生境中节肢动物的空间分布,既与灌丛本身生理生态学特性相关,也与季节性降雨和温度等气象条件的改变密切相关。  相似文献   

高光谱指数法用于确定多枝柽柳(Tamarix ramosissima)蒸腾速率     

王珊珊  陈曦  周可法  王重 《中国沙漠》2014,34(4):1023-1030

蒸腾速率(Tr)是植物生理生态学研究中表征蒸腾耗水的常用指标,研究植物的蒸腾耗水有助于了解当地生态系统稳定性和水资源的可持续利用,但在遥感应用尤其在干旱区遥感应用中很少被使用。本文以古尔班通古特沙漠南缘的主要建群种多枝柽柳(Tamarix ramosissima)作为研究对象,应用高光谱指数法对其Tr日变化过程进行研究,寻找和确定最佳的Tr光谱指数。选择的6个光谱指数判定系数R2介于0.06~0.73,其中简单比值(SR)光谱指数有最高的判定系数(R2=0.73)、较低的均方根误差(RMSE=0.24)和较为简单的形式,光谱范围处于近红外波段(1 645~1 655nm)/(1 775~1 785nm)。SR作为Tr最佳光谱指数,对植被水分关系变化敏感,能够较好地记录和监测Tr日变化过程,有益于揭示光谱指数物理和生理机制。  相似文献   

A dredged material solidification treatment for fill soils in East China: A case history     

Yinghao Huang  Chan Dong  Chunlei Zhang  Kai Xu 《Marine Georesources & Geotechnology》2017,35(6):865-872

Large amounts of sediments are dredged annually from Chinese oceans. Dredged materials (DMs) possess poor geotechnical properties and are normally treated as waste. This paper presents the first large-scale engineering application of DM solidification treatment in China. The technique has been used to treat approximately 1.8?×?10⁶?m³ of DM from Taihu Lake to produce fill soils. Portland cement was chosen as the solidification material, the amount of which is confirmed through indoor unconfined compressive strength (UCS) tests. Special solidification machines process DM at 120?m³/hours. Field-based DM solidification engineering began in September 2006. Curing specimens were examined over 28 days. Results show that both UCS and failure strain of solidified DM could meet fill soil requirements. Bearing capacity was also assessed with a cone penetrometer test. Samples were examined after 2 years (after project completion), and the mean UCS of the specimens was 237.2?kPa, which completely satisfied the engineering request. Wuxi Taihu City Science and Technology Industrial Park has now been established on top of the solidified DM storage yard. The successful engineering of such facilities results in economic and environmental benefits; thus, engineering applications of DM solidification treatment are widely promoted in China.  相似文献   

茅山东部地区第三纪两期玄武岩综合地质特征   总被引：1，自引：0，他引：1  

陈炯达  戴健  张文英 《江苏地质》1999,23(4):212-215

茅山东部地区第三纪两期玄武岩 ,在岩石地层上命名为凉帽顶火山岩锥、方山火山岩锥 ,分别隶属于渐新世三垛组和中—上新世雨花台组 ,相当于两个火山旋回 ,在岩石学、岩石化学、地球化学上有一定的演化规律。两期玄武岩均属钠质碱性玄武岩系列、B类岩浆 ,原始岩浆来源于深部上地幔  相似文献