Modelling river water temperature using deterministic,empirical, and hybrid formulations in a Mediterranean stream

River water temperature is a common target of water quality models at the watershed scale, owing to its principal role in shaping biogeochemical processes and in stream ecology. Usually, models include physically‐based, deterministic formulations to calculate water temperatures from detailed meteorological information, which usually comes from meteorological stations located far from the river reaches. However, alternative empirical approaches have been proposed, that usually depend on air temperature as master variable. This study explored the performance of a semidistributed water quality application modelling river water temperature in a Mediterranean watershed, using three different approaches. First, a deterministic approach was used accounting for the different heat exchange components usually considered in water temperature models. Second, an empirical approximation was applied using the equilibrium temperature concept, assuming a linear relationship with air temperature. And third, a hybrid approach was constructed, in which the temperature equilibrium concept and the deterministic approach were combined. Results showed that the hybrid approach gave the best results, followed by the empirical approximation. The deterministic formulation gave the worst results. The hybrid approach not only fitted daily river water temperatures, but also adequately modelled the daily temperature range (maximum–minimum daily temperature). Other river water features directly dependent on water temperature, such as river intrusion depth in lentic systems (i.e. the depth at which the river inflow plunges to equilibrate density differences with lake water), were also correctly modelled even at hourly time steps. However, results for the different heat fluxes between river and atmosphere were very unrealistic. Although direct evidence of discrepancies between meteorological drivers measured at the meteorological stations and the actual river microclimate was not found, the use of models including empirical or hybrid formulations depending mainly on air temperature is recommended if only meteorological data from locations far from the river reaches are available. Copyright © 2008 John Wiley & Sons, Ltd.     

THE CHARACTERISTIC AND CAUSE OF SEA WATER INTRUSION AND POLLUTION IN SOUTH LIAODONG PENINSULA

Based on various patterns of groundwater and their abundance characters in south Liaodong Peninsula, the distribution, stage, pattern and characters of sea water intrusion in the serious sea water intrusion areas are analysed. The reasons to cause sea water intrusion are uneven precipitation, limited recharge of surface water, artificial overpumping, lithology and geological structure. It can provide scientific basis for reasonable utilization of limited water resource in line with the local conditions.     

Mathematical modelling of sea water intrusion,Nauru Island

A two-dimensional finite element model for density dependent groundwater flow was calibrated to simulate sea water intrusion in Nauru Island in the Central Pacific Ocean. Nauru Island occupies an area of 22 km² and supports a population of 8500. The island has been mined for its phosphate deposits and current reserves indicate that the mine has about eight years life remaining. The water supply of the island is about one third dependent on imported water which is also used as ballast on the phosphate ships. Imported water will not be available in the future, and a hydrogeological investigation shows that the island is underlain by a fresh water layer, less than 5 m thick. The freshwater layer overlies a thick transition zone of brackish water which in turn overlies sea water. Simulation of several management options shows that it is possible to substitute current importation of fresh water by careful extraction from the groundwater resources of the island.     

长乐-南澳构造带白垩纪“片麻状”浆混杂岩的成岩机制研究——以泉州肖厝岩体为例

闽东南长乐南澳构造带沿线出露大面积白垩纪花岗岩岩基,普遍存在岩浆混合现象,肖厝侵入岩是其中的代表性岩体.野外观察和化学分析表明,肖厝侵入岩由二长花岗岩和辉长闪长岩、以及该两种混合端员岩浆混合形成的闪长质-花岗闪长质-花岗质过渡岩类组成;岩石总体富碱、富LREE和LILE、贫HFSE; A/CNK=0.82～1.05,属准铝质微过铝质钙碱性系列,部分受流体交代的岩石A/CNK值可升高至1.69;岩浆混合过程中发生了元素的选择性富集/亏损和同位素组成的均一化,（87Sr/86Sr）为0.7055～0.7061,εNd（t）为-1.9～-3.0.锆石年代学研究表明,肖厝侵入岩的岩浆混合开始于约136Ma,于121Ma时初始侵位于下地壳.结合区域地质特征,分析了肖厝侵入岩的成岩机制,提出岩体侵位早于长乐-南澳构造带的变质变形作用,两者不存在成因上的联系;118～～100Ma时该构造带曾发生过深层次地壳逆冲推覆,使形成于中—下地壳的韧性剪切带和肖厝侵入岩共同快速上升至地表.     

高密度电阻率法在咸水入侵监测中的应用

应用高密度电阻率法测量手段,结合水质调查取样,对山东寿光市咸水入侵过渡带的基本特征进行了研究。通过对典型高密度电阻率法测量剖面的视电阻率进行分析,初步确定10 Ω;m作为该区域咸淡水分界线的视电阻率指示值,并初步推断了咸淡水过渡带的咸水区、咸淡水过渡区及淡水区的位置。结果表明高密度电阻率法具有高效、省时、成本低等优点,可以配合其他方法,作为大范围咸水入侵监测的有效手段。     

河北沿海海侵灾害初探

文中以包含海进、海岸侵蚀和海水入侵的广义“海侵”概念,论述河北沿海地区海侵现状及其危害,探讨海侵产生的自然原因和人为活动的影响,在此基础上,评估海侵发展趋势。     

不同干燥方法对重塑膨润土压汞试验用土样的影响试验研究

采用风干法、烘干法和冻干法分别对不同含水率的重塑膨润土进行干燥制样,利用压汞试验得到的累积进汞量曲线,对重塑膨润土进行了孔隙尺度划分,根据测试结果对土样孔隙尺度分布特征进行了定量分析。试验结果表明：采用风干法、烘干法和冻干法干燥制样后土体孔隙分布存在较大的差异性,土样的含水率越高,差异越明显;风干法、烘干法干燥土样会引起孔隙收缩,导致土体微孔隙特征的变化,冻干法不会引起孔隙收缩,因而不会导致土体微孔隙特征的变化。由此得出了干燥重塑膨润土制备压汞试验用土样最好的干燥方法是冻干法这一结论     

对二郎坪群火神庙组物质组成的质疑与再认识

经研究证明，前人建立的二郎坪群火神庙组确有少量的亚碱性双峰式火山岩。这些火山岩零星地分布在几个地区，走向不连续，出露宽度一般为数百米。构成该组主体的是一条规模宏伟的侵入岩带，其岩石组合为辉长岩－闪长岩－石英闪长岩－斜长花岗岩－花岗岩，总体上表现为正序岩浆演化序列。这些侵入岩普遍经历了三个阶段的变形变质作用，即第一阶段为韧性变形；第二阶段为静态重结晶；第三阶段为带状褶劈理，表现了复杂而漫长的构造演化史。     

Statistical approach to determine the salinized ground water flow path and hydrogeochemical features around the underground LPG cavern,Korea

The ground water flow path of the coastal area in the Yellow Sea, Korea, was interpreted using both the cross‐correlation analysis of hydraulic properties and the principal component analysis (PCA) of ground water chemistry. Data was obtained from observation wells in the underground liquefied petroleum gas (LPG) cavern constructed in the coastal area of Pyeongtaek. Cross‐correlation results showed that the operating pressure became more influenced on artificial factors for the variation of the groundwater level of the study area (45–66% of correlation coefficient) even though its affecting area was limited to the region with fractures or faults, and also showed that the delay time from the variation of operating pressure to the fluctuation of ground water level were relatively long periods (28–31 days). Three hydrogeochemical events (encrusted cement dissolution, host rock dissolution, and seawater intrusion), which were dominantly influenced on ground water quality, could be induced from the result of PCA. Quantitative evaluation for these events using the mixed equation with principal component scores suggest that the dissolution of encrusted cement materials was the predominant factor (39·0% of the total mixed proportion) to change the chemical composition of the seepage water during the ground water flow from the observation wells to the cavern. Integration of the statistical results also imply that ground water flow and hydrogeochemistry were predominantly affected by artificial factors such as cavern operation pressure and dissolution of encrusted cement materials, which were interdependent factors on the observation wells with high cross‐correlation coefficients and pH. Copyright © 2007 John Wiley & Sons, Ltd.     

高挂山—牛头寨地区小型环形影象构造分析及其找矿意义

高挂山—牛头寨地区,通过大比例尺航片解译,发现6个大小不等的小型环形影象信息。这些环形影象与岩浆活动、已知矿床、矿化点、重砂异常、物化探异常等的分布有着内在的联系。为预测找矿远景区和找隐伏矿床提供了影象依据。