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341.
The groundwater table has been declining at a rate of 0.65 m/yr in Luancheng County since large scale groundwater extraction
carried out in the 1960s. The drop of precipitation, substantial increase in agricultural output, variations of crop planting
structure and construction of water conservancy projects in the headwater area all tie up with the decline of the groundwater
table. On the basis of analyzing the hydrogeological conditions and the water resources utilization of Luancheng County, a
three-dimensional groundwater flow model was developed to simulate the county’s groundwater flow through finite-difference
method using Visual Modflow software. We divide the research field into four parts after analyzing the hydrogeological condition.
Based on parameter calibration and adjustment using measured data, the hydraulic conductivity and specific yield were simulated.
Using the calibrated model, we analyze the agricultural water saving potentiality and its influence on the groundwater. The
results are as follows: (1) if we decrease the amount of water extracted by 0.14xl08 m3, the average groundwater table of the five observation wells in December will rise by 0.33 m; (2) if we decrease the water
by 0.29x 108m3, the average groundwater table of the five observation wells in December will rise by 0.64 m; and (3) if we increase the
water by 0.29 x 108m3, the average groundwater table of the five observation wells in December will decline by 0.45 m. So we can draw a conclusion
that controlling the agricultural water use is an important way to prevent the decline of groundwater table. 相似文献
342.
Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin
River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed
that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample
locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in
the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations
in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed
that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from
the Huolin River channel. 相似文献
343.
344.
高密度电阻率法二维成像方法及其应用 总被引:6,自引:0,他引:6
高密度电阻率法在工程勘察和环境监测中是一种很重要的勘探手段,高密度电阻率法二维成像理论与方法的研究在理论和实际应用上都有着很重要的意义。随着地球物理反演和成像技术研究的兴起和发展,层析成像技术在高密度电阻率法中的应用,提高了高密度电阻率法的勘探质量和精度。本文献电阻率法层析成像技术的前提条件及高密度电阻率法二维成像理论与方法进行了粗浅探讨,最后给出了一些应用实例。 相似文献
345.
应用微分求积区域分裂法求解非线性奇异摄动问题。数值实验结果表明,该法准确度高,计算量少。 相似文献
346.
当代世界地质调查工作发展趋势 总被引:4,自引:0,他引:4
20世纪80年代以来,经济全球化的发展、高新技术的广泛应用、世界人口的迅速增长和环境问题的日益严峻,对地质调查工作产生了巨大的冲击,地质调查的驱动机制、主要任务和工作内容、技术手段、服务意识等都发生了很大的变化。总体趋势为:需求驱动——地质调查工作的驱动机制由传统的供给驱动型向需求驱动型转变;领域拓宽——地质调查的研究领域不断拓展,从以寻找、发现矿产资源为主的矿产资源型转变为兼顾资源与环境保护、灾害减轻的资源与环境并重的社会型;技术先导——地质调查的技术手段发生了根本性变化,地质调查传统的“老三件”正逐渐被“新三件”所替代;服务优先——地质调查的服务意识不断增强。 相似文献
347.
Multi-parameter studies (stable isotopes in carbonate and organic matter, pigment,organic carbon and nitrogen contents) from a 660-yr continuous sediment core from Lake Cheng-hai, a closed, eutropic lake in southern China, provide information on lake historical eutrophi-cation. During the last 660 years, great changes have taken place in productivity and eutrophi-cation of Lake Chenghai in response to human activities. In 1690, the productivity of the lakebegan to increase as Lake Chenghai became closed from agriculture in the lake‘‘ s watershed. In 1942, Lake Chenghai evolved to eutrophic state, marked by an increase in organic carbon, ni-trogen, CaC03, pigment contents and obvious negative values of stable isotopes, which is more or less simultaneous with the large-scale population immigration during the period. In 1984, in-tensive human activities induced modern lacustrine productivity and eutrophic level. Human-in-duced trophic changes during the past few decades have affected the Lake Chenghai ecosystem tosuch an extent that it has never experienced before in the last 660 years. 相似文献
348.
The bulk composition of organic matter and saturated and aromatic hydrocarbons extracted from 16 samples collected from two Kuperschiefer profiles in the Rudna mine,Southwest Poland has been analyzed to study the role of organic matter during base metal enrichment in the Kupferschiefer shale.The results indicated that the extract yields and saturated hydrocarbon yields decreased with increasing base metal contents.GC and GC/MS analyses indicated that n -alkanes and alkylated aromatic compounds were depleted and may have served as hydrogen donators for thermochemical sulfate reduction.The enrichment of base metal is closely connected with the destruction of hydrocarbons. 相似文献
349.
From the studies of ore deposit geologic settings,sulfur isotopes,lead isotopes,carbon isotopes and oxygen isotopes,fluid inclusions and petrochemistry in this paper,the authors have drawn a conclusion that the ore-forming hydrothermal solutions are the high-temperature magmatic hydrothermal solutions for the gold ore deposit,and at the same time,the involvemety of crustal materials can not be ruled out .It is the first time that the authors have proposed that the Laozuoshan gold-ploymetallic ore deposit in Heilongjiang Province was formed in the calc-alkaline series environment at the margin of an active continent. 相似文献
350.
1IntroductionTheHongshijinggolddepositislocatedinthenorthofLuobupouLakeofRuoqiang ,about 30 0kmsouthwestofHamiCity ,Xinjiang .ItwasdiscoveredbytheSixthGeologicalTeamofXinjiangduringgeo chemicalexploration .TheHongshijinggolddeposit,whichoccursinthegold bearingformationcomposedofMiddleandLateCarboniferousvolcanicandpyroclasticrocks ,isabrittle ductileshearzonetypegolddepositcontrolledbyariftbelt.TheHongshijinggolddepositislocatedinthesouthwestoftheHongshi jing -Maotoushanmineralizationb… 相似文献