Using live vegetation volume to analyze the effects of plot Pinus massoniana Lamb on water and soil conservation under natural rainfall events

The 3-D spatial distributions of vegetation are of great significance for water and soil conservation but are rarely concerned in literatures. The live vegetation volume （LVV） was used to relate to water/soil loss under 144 natural erosive rainfall events from 2007 to 2010 in a typical water-eroded area of southern China. Quadratic polynomial regression models were established for five pure tree （Pinus massoniana Lamb） plots between LVV and water （rtmoff）/soil conservation effects （RE/SE）. RE/SE corresponds to the ratios of runoff depth/soil loss of the pure tree plots to that of the control plot under each rainfall event. Increasing LVV exhibits descending （DS）, descending-ascending （DA）, ascending-descending （AD）, and ascending （AS） trends in the LVV-RE and LVV-SE curves. The effects of soil conservation on the plots were generally more noticeable than the effects of water conservation, and most of the RE and SE values reflected the positive effects of water and soil conservation. The effects were mainly positive under heavy rains （e.g., rainfall erosivity, R = 140 MJ mm ha-l h, maximum 30 min intensity, I30 = 16 mm h-l）, whereas the effects were mainly negative under light rains （e.g., R = 45 MJ mm ha-1 h, I30 = 8 mm h-l）. The trees＇ water/soil conservation effects notably transformed when rainfall erosivity and intensity were lower than the positive or negative effects to a certain threshold. About 50% rainfall events led to obvious transform effects when LVVs were near 0.5 or 0.6. These results are able to aid in the decision making on the forest reconstruction in water-eroded areas.     

一个储量可再生的石油地质模型

最新石油地质基础研究表明,目前正在开采的油气藏可能存在大规模的油气补充,以往勘探地质模型、开发地质模型、三次采油地质模型都没有考虑到储量可增长的因素,可能需要修正。建议国家有关部门设立专项研究,以期为油气勘探开发部署和后期调整提供可靠的地质依据。     

裂隙岩质边坡地下水渗流数值模拟

本文从反倾向岩质高边坡的渗流特征和渗流普遍规律出发,根据渗流力学知识,建立数学模型,通过渗流数值模拟计算分析了渗透压力、水头变化规律以及对岩质边坡稳定性的影响.     

高应变法在判定大直径灌注桩缺陷中的应用

测试数据准确可靠的高应变法检测,能够定量分析基桩缺陷,准确判定缺陷位置。通过工程桩的低应变法和高应变法对桩身完整性判定分析的工程实例,结合钻芯法验证,总结高应变法在不同情况下对桩身完整性的评定。     

The response of the azimuthal component of the ionospheric electric field to auroral arc brightening

We have analyzed the response of azimuthal component of the ionospheric electric field to auroral arc activity. We have chosen for analysis three intervals of coordinated EISCAT and TV observations on 18 February, 1993. These intervals include three kinds of arc activity: the appearance of a new auroral arc, the gradual brightening of the existing arc and variations of the arc luminosity. The arcs were mostly east-west aligned. In all cases, the enhancement of arc luminosity is accompanied by a decrease in the westward component of the ionospheric electric field. In contrast, an increase of that component seems to be connected with arc fading. The observed response is assumed to have the same nature as the short circuit of an external electric field by the conductor. The possible consequence of this phenomenon is discussed.     

Bulk-rock Major and Trace Element Compositions of Abyssal Peridotites: Implications for Mantle Melting, Melt Extraction and Post-melting Processes Beneath Mid-Ocean Ridges

This paper presents the first comprehensive major and traceelement data for 130 abyssal peridotite samples from the Pacificand Indian ocean ridge–transform systems. The data revealimportant features about the petrogenesis of these rocks, mantlemelting and melt extraction processes beneath ocean ridges,and elemental behaviours. Although abyssal peridotites are serpentinized,and have also experienced seafloor weathering, magmatic signaturesremain well preserved in the bulk-rock compositions. The betterinverse correlation of MgO with progressively heavier rare earthelements (REE) reflects varying amounts of melt depletion. Thismelt depletion may result from recent sub-ridge mantle melting,but could also be inherited from previous melt extraction eventsfrom the fertile mantle source. Light REE (LREE) in bulk-rocksamples are more enriched, not more depleted, than in the constituentclinopyroxenes (cpx) of the same sample suites. If the cpx LREErecord sub-ridge mantle melting processes, then the bulk-rockLREE must reflect post-melting refertilization. The significantcorrelations of LREE (e.g. La, Ce, Pr, Nd) with immobile highfield strength elements (HFSE, e.g. Nb and Zr) suggest thatenrichments of both LREE and HFSE resulted from a common magmaticprocess. The refertilization takes place in the ‘cold’thermal boundary layer (TBL) beneath ridges through which theascending melts migrate and interact with the advanced residues.The refertilization apparently did not affect the cpx relicsanalyzed for trace elements. This observation suggests grain-boundaryporous melt migration in the TBL. The ascending melts may notbe thermally ‘reactive’, and thus may have affectedonly cpx rims, which, together with precipitated olivine, entrappedmelt, and the rest of the rock, were subsequently serpentinized.Very large variations in bulk-rock Zr/Hf and Nb/Ta ratios areobserved, which are unexpected. The correlation between thetwo ratios is consistent with observations on basalts that D_Zr/D_Hf< 1 and D_Nb/D_Ta < 1. Given the identical charges (5⁺ forNb and Ta; 4⁺ for Zr and Hf) and essentially the same ionicradii (R_Nb/R_Ta = 1·000 and R_Zr/R_Hf = 1·006–1·026),yet a factor of 2 mass differences (M_Zr/M_Hf = 0·511 andM_Nb/M_Ta = 0·513), it is hypothesized that mass-dependentD values, or diffusion or mass-transfer rates may be importantin causing elemental fractionations during porous melt migrationin the TBL. It is also possible that some ‘exotic’phases with highly fractionated Zr/Hf and Nb/Ta ratios may existin these rocks, thus having ‘nugget’ effects onthe bulk-rock analyses. All these hypotheses need testing byconstraining the storage and distribution of all the incompatibletrace elements in mantle peridotite. As serpentine containsup to 13 wt % H₂O, and is stable up to 7 GPa before it is transformedto dense hydrous magnesium silicate phases that are stable atpressures of 5–50 GPa, it is possible that the serpentinizedperidotites may survive, at least partly, subduction-zone dehydration,and transport large amounts of H₂O (also Ba, Rb, Cs, K, U, Sr,Pb, etc. with elevated U/Pb ratios) into the deep mantle. Thelatter may contribute to the HIMU component in the source regionsof some oceanic basalts. KEY WORDS: abyssal peridotites; serpentinization; seafloor weathering; bulk-rock major and trace element compositions; mantle melting; melt extraction; melt–residue interaction; porous flows; Nb/Ta and Zr/Hf fractionations; HIMU mantle sources     

三江源地区土壤侵蚀特点

三江源地区地域辽阔,土壤侵蚀复杂多样.近年来土壤侵蚀加剧,生态环境严重退化.以2000年土壤侵蚀调查的数据成果为基数.并与更新后的2005年数据成果比较,进行土壤侵蚀动态变化分析.对三江源地区不同类型土壤侵蚀区的土壤侵蚀现状做了较全面的分区评价.同时对作为典型区域的黄河源头区12个县的2000年1:10万Landsat 5 TIM假彩色合成影像,通过野外调查建它解译标志来分析该区植被覆盖状况,对该区典型区域的土壤侵蚀现状做了定量评价.根据评价结果,对三江源地区土壤侵蚀的发展趋势做了预测.     

浅谈全国第二次土地调查项目的几个关键环节

介绍了全国第二次土地调查项目中调绘底图生产、土地调查、田坎系数测定、农村宅基地调查等关键环节,结合实际生产,分析了各环节的重要性及实施情况。     

On the solar cycle dependence of winds and planetary waves as seen from mid-latitude D1 LF mesopause region wind measurements

At the Collm Observatory of the University of Leipzig LF D1 low-frequency total reflection nighttime wind measurements have been carried out continuously for more than two decades. Using a multiple regression analysis to derive prevailing winds, tides and the quasi-2-day wave from the half-hourly mean values of the horizontal wind components, monthly mean values of mesopause wind parameters are obtained that can be analysed with respect to long-term trends and influences of solar variability. The response of the prevailing wind to the 11-year solar cycle differs throughout the year. While in winter no significant correlation between the zonal prevailing wind and solar activity is found, in spring and summer a negative correlation between the TWC can be seen from the measurements. This is connected with stronger vertical gradients of the zonal prevailing wind during solar maximum than during solar minimum. Since the amplitude of the quasi-2-day wave is dependent on the zonal mean wind vertical gradient, this is connected with a positive correlation between solar activity and quasi-two-day wave activity.Paper Presented at the Second IAGA/ICMA (IAMAS) Workshop on Solar Activity Forcing of the Middle Atmosphere, Prague, August 1997     

兼顾志愿者地理信息的国家应急测绘公众服务平台设计

随着互联网技术的进步和新一代网络信息传播模式的深入发展,志愿者地理信息的研究和应用日益广泛,但由于其规范性和均一性方面的缺陷,在应急公共服务领域,志愿者信息的有效利用依旧是亟需突破的难题。本文将重点介绍国家应急测绘公众服务平台设计思路和总体架构,并结合志愿者地理信息特点,探讨该类信息在国家应急测绘公众服务平台建设中的处理流程和应用模式,力求在应急信息资源共享和服务平台共建方面进行新的尝试,为我国突发事件应急体系建设提供有益实践。