Major ions in typical subterranean rivers and their anthropogenic impacts in southwest karst areas,China   总被引：5，自引：0，他引：5  

Fang Guo  Guanghui Jiang  Daoxian Yuan 《Environmental Geology》2007,53(3):533-541

Subterranean rivers contain much of the groundwater in karst and supply many local people in southwest China. The quality of groundwater in subterranean rivers is of concern because of its sensitivity to anthropogenic activity. Groundwater samples in a rural catchment were collected at the discharge point, and the concentrations of major ions including potassium, sodium, calcium, magnesium, chloride, sulfate, nitrate and bicarbonate were analyzed in this study. Rainfall and discharge were also observed at the same time. It could be concluded from the data that the concentrations of sulfate and nitrate had a peak in the rainy season when the concentrations of sodium, calcium, magnesium and bicarbonate were low. The concentrations of potassium and chloride changed randomly throughout the year. The concentration of major ions in flood process was not completely controlled by discharge. Only the concentrations of nitrate and sulfate had obviously increased during the past two decades. It was believed that dilution, eluviation, karst erosion and anthropogenic activity can explain the ion variations and hence this study helps to understand environmental problem in karst.  相似文献   

RESPONSE OF SEDIMENT DISCHARGE TO ECOHYDROLOGICAL FACTORS IN LUERGOU CATCHMENT BASED ON WAVELET ANALYSIS     

Yuan TIAN Xinxiao YU Derong SU Xin YANG 《国际泥沙研究》2007,22(1):70-77

The response of sediment discharge rate to the following four ecohydrological factors: temperature, rainfall, evapotranspiration (ET), and stream flow was evaluated by conducting wavelet analysis on Luergou small catchment data ranging from 1982 to 2000. For sediment discharge rate, there was an overall trend of reduction that included a periodic oscillation of 6 to 7 years per cycle. Rainfall also had an overall trend of reduction that included two periodic oscillations of 7 years per cycle and 2 years per cycle, respectively. Stream flow had the same trend as rainfall but had one periodic oscillation of 6 to 7 years per cycle. In contrast with rainfall and stream flow, the trends for temperature and ET each showed an overall increasing tendency, and both had the same two periodic oscillations of 6 to 7 years per cycle and 4 years per cycle, respectively. The sediment discharge rate had significant relationships with the four ecohydrological factors, with stream flow and rainfall having positive correlations, while ET and temperature had negative correlations. The correlation between ET and sediment discharge rate became stronger when ET was compared to the sediment discharge rate of the following year. The relationship between sediment discharge rate and the four ecohydrological factors was further expressed by the multi-linear regression model that was constructed, which makes sediment discharge rate a function of stream flow, rainfall, ET, and temperature.  相似文献   

土耳其贝帕扎里天然碱矿钻井工程MWD实地校核     

胡汉月向军文  董迪壮 《探矿工程》2007,34(7):1-4

土耳其贝帕扎里天然碱矿采卤工程是目前世界范围内采用对接井水溶开采方法进行采矿的最大规模的天然碱采矿工程。在对接井施工过程中，由于出现了地磁变化异常和地质条件变化，致使MWD导向系统出现了一定偏差。为减少仪器偏差，设计并对仪器进行了实地校核。校核结果表明，探管的安装条件对其数据精度有较大的影响。其校核结果被应用于实际生产中，起到了良好的指导作用。  相似文献   

Rainfall interception in three contrasting lowland rain forest types in Central Kalimantan, Indonesia   总被引：3，自引：0，他引：3  

R.R.E. Vernimmen  L.A. Bruijnzeel  A. Romdoni  J. Proctor   《Journal of Hydrology》2007,340(3-4):217-232

Rainfall interception was quantified and modeled for a Lowland Evergreen Rain Forest (LERF) and two Heath Forests (HF) of contrasting stature during a one-year period at a remote site in Central Kalimantan, Indonesia. Throughfall was measured using a roving gauge approach using 18–20 gauges per forest type. Throughfall was 82.8% of incident rainfall in the LERF vs. 89.1% in tall HF and 76.7% in stunted HF. Corresponding stemflow fractions were 0.8%, 1.3% and 2.0% of rainfall, respectively. Interception losses derived for the LERF (16.4%) and the tall HF (9.6%) were close to findings obtained for similar forest types elsewhere but the high interception loss for the stunted HF (21.3%) was unexpected. On the basis of canopy structural characteristics and wet canopy evaporation modeling it is concluded that throughfall in the stunted HF was underestimated and that the specific nature of the HF required a more intensive sampling arrangement. Throughfall sampling schemes in tropical forests, associated errors and hydrological implications are discussed.  相似文献   

均生函数场预报模型对降水预报的试验研究   总被引：4，自引：1，他引：3  

张万诚  解明恩  张荣华 《高原气象》2000,19(3):379-384

基于均生函数的处理原则,运用经验正交分解方法,将正交展开的时间系数俄为预报因子,并引入逐步算法进行因子筛选建立预报模型。将均生函数场预报模型用于云南省汛期雨量及５月雨量预报试验。结果表明：用这种模型作区域性降水预报有一定的优越性,并可作多步预测,是一咱滚动客观预报方法。  相似文献   

Local boundary-layer development over burnt and unburnt tropical savanna: an observational study     

Chris K. Wendt  Jason Beringer  Nigel J. Tapper  Lindsay B. Hutley 《Boundary-Layer Meteorology》2007,124(2):291-304

Fire scars have the ability to radically alter the surface energy budget within a tropical savanna by reducing surface albedo, increasing available energy for partitioning into sensible and latent heat fluxes and increasing substrate heat flux. These changes have the potential to alter boundary-layer conditions and ultimately feedback to local and regional climate. We measured radiative and energy fluxes over burnt and unburnt tropical savanna near Howard Springs, Darwin, Australia. At the burnt site a low to moderate intensity fire, ranging between 1,000 and 3,500 kW m⁻¹, initially affected the land surface by removing all understorey vegetation, charring and blackening the ground surface, scorching the overstorey canopy and reducing the albedo. A reduction in latent heat fluxes to almost zero was seen immediately after the fire when the canopy was scorched. This was then followed by an increase in the sensible heat flux and a large increase in the ground heat flux over the burnt surface. Tethered balloon measurements showed that, despite the presence of pre-monsoonal rain events occurring during the measurement period, the lower boundary layer over the burnt site was up to 2^°C warmer than that over the unburnt site. This increase in boundary-layer heating when applied to fire scars at the landscape scale can have the ability to form or alter local mesoscale circulations and ultimately create a feedback to regional heating and precipitation patterns that may affect larger-scale processes such as the Australian monsoon.  相似文献   

EDM三角高程测量在大型桥梁中的应用     

傅新军  崔巍 《现代测绘》2007,30(3):16-18

通过对EDM三角高程测量基本原理的分析,确定测量误差的主要来源,并在施测过程中制定相应的质量控制措施,保证EDM三角高程测量满足桥梁工程测量精度要求,并以南京大胜关长江大桥为例进行说明.  相似文献   

利用多普勒雷达定量估测降水试验   总被引：2，自引：0，他引：2  

徐继延  郭建华  蔡冠勋 《气象与减灾研究》2007,30(4):52-56

利用南昌多普勒雷达体扫资料和抚州市气象台站自记雨量资料,建立了定量估测降水方程,在抚河流域的不同区域进行了定量估测降水对比试验,据此给出了有利人工增雨作业的多普勒雷达产品判据。结果表明,综合利用多仰角基本反射率、回波顶高和垂直积分含水量进行定量估测降水,效果明显好于单独利用单仰角基本反射率估测定量降水。在降水量≤3 mm时,综合定量估测降水值、常规定量估测降水值与实测降水值比较吻合;在降水量>3 mm、特别是出现较大降水(>5 mm)时,与常规定量估测降水值相比,综合定量估测降水值更接近实测降水值。  相似文献   

数值剖析0411号热带气旋位置不连续变化和强度突变   总被引：1，自引：0，他引：1  

陈桂兴  林良勋  冯业荣  林钢  袁卓建 《气象学报》2007,65(4):588-600

为探究竟0411号热带气旋(TC0411)出现数小时内向北"走"了300多公里且急剧加强的异常现象,根据TC0411经向环流特征(辐合抬升ω<0的水汽多来自偏南风v>0)及其与第2类条件不稳定(CISK)机制的密切关系,运用反映南海经向环流的线性诊断模式(包含边界效应、各稳定度及17个内力因子),对TC0411进行定量诊断。结果表明:南海东北部深厚强盛的偏南风急流及其造成的弱惯性稳定度为TC0411发生发展(向北不连续位移)提供了有利水汽输送和抬升(驱动)条件。其中,对偏南风有突出正贡献的边界效应与5°N西南夏季风和西太平洋东南风的辐合有关;驱动地转南风的气压梯度力与中南半岛季风槽、西太平洋高压和高层东风扰动有关。驱动非地转南风的内力因子主要是与斜压不稳定有关的平均经向温度平流、与西南风急流切变场有关的涡动西风动量经向输送、与夏季风环流和高层东风扰动相互作用有关的平均西风动量纬向输送及与非对称动力热力场有关的涡动温度平流。TC0411向北不连续位移实质为22.7°N附近生成新热带低压(TD)和19°N附近TD消亡的结果。2004年7月26日20时—27日02时激发22.7°N附近上升运动(19°N附近下沉运动)的主要因子是平均经向温度平流和涡动西风动量水平输送(平均西风动量纬向输送和涡动温度平流)。27日02—14时使新TD加强为热带风暴(TS)并维持的主要因子是潜热加热和平均经向温度平流。根据以上分析,建议业务预报应着眼于深厚强盛西南风急流和温度平流的共同作用。  相似文献   

邯郸地区一次登陆台风大暴雨过程观测分析   总被引：2，自引：8，他引：2  

张海霞  崔晓鹏  康凤琴  蔡守新 《高原气象》2007,26(5):980-991

受登陆台风"海棠"减弱后低压与东移锋面云系的共同影响,2005年7月21日夜间到23日早晨邯郸地区出现了大范围的暴雨天气。本文从天气形势、水汽输送特征、云系演变特征和大气不稳定条件等方面进行分析,探讨了这次登陆台风暴雨天气的成因。结果表明,台风低压、稳定少变的副热带高压以及500 hPa低槽相互作用,共同造成了这次暴雨天气过程,高纬弱冷空气南下,与台风携带的暖湿空气相遇,加之太行山地形的影响,造成暖湿空气抬升,使得冀南地区产生中尺度对流云团,进而发生强降水。地面自动站以及加密站风场资料分析指出,低空偏北风与偏东风之间的中尺度辐合线对暴雨发生有重要作用,其出现的时间和位置决定了中尺度暴雨天气的发生时间和位置。在水汽输送方面,西部山区的暴雨区水汽主要来源于南海和东海,而东部平原地区的大暴雨,其水汽主要来源于南海。简单的层结分析表明,暴雨区上空存在对流不稳定和对称不稳定共存的现象,两者共同为系统发展和暴雨发生提供了不稳定条件。  相似文献