Seasonal connections between meteoric water and streamflow generation along a mountain headwater stream     

Sam J. Leuthold  Stephanie A. Ewing  Robert A. Payn  Florence R. Miller  Stephan G. Custer 《水文研究》2021,35(2):e14029

In snowmelt-driven mountain watersheds, the hydrologic connectivity between meteoric waters and stream flow generation varies strongly with the season, reflecting variable connection to soil and groundwater storage within the watershed. This variable connectivity regulates how streamflow generation mechanisms transform the seasonal and elevational variation in oxygen and hydrogen isotopic composition (δ¹⁸O and δD) of meteoric precipitation. Thus, water isotopes in stream flow can signal immediate connectivity or more prolonged mixing, especially in high-relief mountainous catchments. We characterized δ¹⁸O and δD values in stream water along an elevational gradient in a mountain headwater catchment in southwestern Montana. Stream water isotopic compositions related most strongly to elevation between February and March, exhibiting higher δ¹⁸O and δD values with decreasing elevation. These elevational isotopic lapse rates likely reflect increased connection between stream flow and proximal snow-derived water sources heavily subject to elevational isotopic effects. These patterns disappeared during summer sampling, when consistently lower δ¹⁸O and δD values of stream water reflected contributions from snowmelt or colder rainfall, despite much higher δ¹⁸O and δD values expected in warmer seasonal rainfall. The consistently low isotopic values and absence of a trend with elevation during summer suggest lower connectivity between summer precipitation and stream flow generation as a consequence of drier soils and greater transpiration. As further evidence of intermittent seasonal connectivity between the stream and adjacent groundwaters, we observed a late-winter flush of nitrate into the stream at higher elevations, consistent with increased connection to accumulating mineralized nitrogen in riparian wetlands. This pattern was distinct from mid-summer patterns of nitrate loading at lower elevations that suggested heightened human recreational activity along the stream corridor. These observations provide insights linking stream flow generation and seasonal water storage in high elevation mountainous watersheds. Greater understanding of the connections between surface water, soil water and groundwater in these environments will help predict how the quality and quantity of mountain runoff will respond to changing climate and allow better informed water management decisions.  相似文献   

利用自回归模型检测地球极移重力效应     

杨学峰  孙和平  徐建桥 《大地测量与地球动力学》2004,24(2):110-114

同时采用4个台站的国际超导重力仪长期连续重力观测资料和国际地球自转服务中心提供的同步地球自转参数，研究了极移引起的地球重力场变化特征。利用自回归模型估计了各序列的功率谱密度和积谱密度，结果表明极移导致的重力效应的主要能量集中在Chandler摆动和周年项附近，叠积后实际重力观测与极移重力信号理论值之间的差异分别为0．4％和3．9％，说明超导重力仪可有效监测极移导致的重力变化。  相似文献   

优化发电能源结构的初探   总被引：1，自引：0，他引：1  

程地卫 《成都信息工程学院学报》2001,16(1):41-45

从我国电力工业发展的角度，浅析了国内外发电能源结构及其变化趋势，作者认为优化我国发电能源结构、采取必要的技术措施，是实现我国电力 工业可持续发的重要途径。  相似文献   

Water transport from the North-east Irish Sea to western Scottish coastal waters: Further observations from time-trend matching of Sellafield radiocaesium     

W.A. McKay  M.S. Baxter 《Estuarine, Coastal and Shelf Science》1985,21(4):471-480

Radiocaesium isotopes, discharged into the North-east Irish Sea from the Sellafield (formerly Windscale) nuclear fuel reprocessing plant in Cumbria, have been employed as flow monitors to update and extend the record of coastal water movement from the Irish Sea to the Clyde Sea area and, further north, to Loch Etive. The temporal trends in radiocaesium levels have been used to determine the extent of water mixing en route and to define mean advection rates. Flow conditions from the Irish Sea have changed considerably since the mid-1970s, the residence time of northern Irish Sea waters being ～12 months during 1978–1980 inclusive. Average transport times of four and six months are estimated for the Sellafield to Clyde and Sellafield to Etive transects respectively. Sellafield ¹³⁷Cs levels in seawater were diluted by factors of 27 and 50 respectively during current movement to the Clyde and Etive areas. The decrease in salinity-corrected ¹³⁷Cs concentrations between the Clyde and Etive suggests that dilution by Atlantic water occurs, the latter mainly entering the Firth of Lorne from the west. The majority (～94%) of the radiocaesium supply to Loch Etive enters the Firth of Lorne via the portion of the coastal current circulating west of Islay, only ～6% arriving via the Sound of Jura.  相似文献   

可移动中继节点在传感器网络中的节能应用     

唐帙  罗惠琼 《成都信息工程学院学报》2005,20(2):147-150

介绍了一种新颖的静态传感器网络实现方法，它利用可移动的中继节点来收集静态传感器网络的数据，有效的节约各传感器节点的能源，延长整个传感器网络的有效工作时间。也可以对该方法进行适当的改进，应用到某些实时性要求较高的场合中去。然后介绍了应用该原理实现的一个通讯协议。  相似文献   

On the practice of estimating fractal dimension   总被引：11，自引：0，他引：11  

James R. Carr  William B. Benzer 《Mathematical Geology》1991,23(7):945-958

Coastlines epitomize deterministic fractals and fractal (Hausdorff-Besicovitch) dimensions; a divider [compass] method can be used to calculate fractal dimensions for these features. Noise models are used to develop another notion of fractals, a stochastic one. Spectral and variogram methods are used to estimate fractal dimensions for stochastic fractals. When estimating fractal dimension, the objective of the analysis must be consistent with the method chosen for fractal dimension calculation. Spectal and variogram methods yield fractal dimensions which indicate the similarity of the feature under study to noise (e.g., Brownian noise). A divider measurement method yields a fractal dimension which is a measure of complexity of shape.  相似文献   

Morphological analysis of the drainage system in the Eastern Alps   总被引：2，自引：1，他引：1  

Jrg Robl  Stefan Hergarten  Kurt Stüwe 《Tectonophysics》2008,460(1-4):263-277

We study the morphology of the major rivers draining the Eastern Alps to test whether the active tectonics of this part of the orogen is reflected in the shape of channel profiles of the river network. In our approach we compare channel profiles measured from digital elevation models with numerically modelled channel profiles using a stream power approach. It is shown that regions of high stream power coincide largely with regions of highest topography and largest uplift rates, while the forelands and the Pannonian Basin are characterised by a significantly lower stream power. From stream power modelling we conclude that there is young uplift at the very east of the Eastern Alps, in the Bohemian Massif and in the Pohorje Range. The impact of the Pleistocene glaciations is explored by comparing properties of rivers that drain in proximal and distal positions relative to the ice sheet during the last glacial maximum. Our analysis shows that most knick points, wind gaps and other non-equilibrium features of catchments covered by ice during the last glaciations (Salzach, Enns) can be correlated with glacial processes. In contrast the ice free catchments of the Mur and Drava are characterized by channels in morphological equilibrium at the first approximation and are showing only weak evidence of the strong tectonic activity within these catchments. Finally, the channel profiles of the Adige and the divide between the upper Rhine and Danube catchments differ significantly from the other catchments. We relate this to the fact that the Adige and the Rhine respond to different base levels from the remainder of the Eastern Alps: The Adige may preserve a record from the Messininan base level change and the Rhine is subject to the base level lowering in the Rhine Graben.  相似文献   

氢化物发生及其在分析检测领域的应用   总被引：2，自引：2，他引：0  

郑大中  郑若锋  王惠萍 《岩矿测试》2008,27(1):55-59

论述了氢化物发生的条件和普遍性及其在分析检测领域的应用,这些领域包括试样分解,分离富集,容量分析、比色分析、原子荧光光谱、原子吸收光谱、电感耦合等离子体原子发射光谱、电感耦合等离子体质谱等分析测试技术。  相似文献   

微型氢化物发生装置在冷原子吸收分光光度法测汞中的应用     

赵延庆 《岩矿测试》2008,27(1):69-70

采用微型氢化物发生装置-冷原子吸收分光光度法测定了焊锡料及纽扣电池中的汞。在酸性介质中,用硼氢化钾将汞离子还原为汞原子,用载气将汞蒸气导入石英管,原子吸收分光光度计在波长253.7 nm处进行测定。选择了实验条件,对共存离子的干扰等进行了考察。方法的检出限为0.34 ng/mL,11次测定的相对标准偏差(RSD)小于6%,加标回收率为94.4%~104.7%。  相似文献   

氢化物发生-原子荧光光谱法直接测定地球化学样品中痕量碲   总被引：2，自引：1，他引：1  

林光西 《岩矿测试》2008,27(2):151-152

采用硝酸-氢氟酸-高氯酸溶解样品,以Fe3+作减缓剂,不需分离富集,用氢化物发生-原子荧光光谱法直接测定地球化学样品中痕量碲。对测定介质、KBH4浓度、铁盐的作用等条件进行试验。方法检出限为0.0031μg/g,精密度(RSD,n=11)<6.10%。方法用于国家一级地球化学标准物质中痕量碲的测定,结果与标准值一致。  相似文献