干旱区主要陆表过程与人类活动和气候变化研究进展

分析了国内外水、土、气、生主要陆表过程的相互作用以及干旱、半干旱区主要陆表过程与气候变化和人类活动互为响应机制的一系列研究成果,提出了未来该研究领域的发展方向应集中在地球表层系统各要素相互作用的综合研究,同时突出人类活动在陆表过程中的主导地位;在研究手段上应基于国家野外科学观测站、生态网络站的长期定位观测,开展干旱、半干旱区不同尺度水、土、气、生过程相互作用机理及其联网对比、集成研究。最终通过深刻理解研究区陆表过程及其调控机理,丰富陆地表层系统科学研究的内涵,带动相关学科在交叉集成研究上的理论创新。     

Seismically induced landslide displacements: a predictive model

Newmark's model for predicting earthquake-induced landslide displacements provides a simple way to predict the coseismic displacements affecting a sliding mass subject to earthquake loading. In this model, seismic slope stability is measured in terms of critical acceleration, which depends on the mechanical soil properties, pore-pressure distribution, and slope geometry. The triggering seismic forces are investigated in terms of energy radiation from the source, propagation, and site effects, based on 190 accelerometric recordings from 17 Italian earthquakes with magnitudes between 4.5 and 6.8. The method is based on the calibration of relations having the general form of an attenuation law that relates the energy of the seismic forces to the dynamic shear resistances of the sliding mass to propagate the expected landslide displacements as an inverse function of the distance from the fault rupture; the amount of displacement computed through these relations provides a criterion to predict the occurrence of slope failures. Finally, maps showing, in a deterministic and a probabilistic way, the potential of seismically induced landslide displacements are displayed as a tool to provide seismic landslide scenarios and earthquake-induced landslide hazard maps, respectively.     

人类活动在放大和减轻山地灾害中所起作用--以太行山区前南峪和真炭沟小流域为例

山地生态环境脆弱性是山地灾害形成的基础。通过太行山两个典型小流域在 1996年 8月的洪涝灾情形成的对比分析 ,揭示了人类活动在山地环境脆弱性方面所起的重要作用。合理的土地利用方式和水土保持措施可以有效地减轻流域对洪涝灾害的脆弱性。在相同的自然条件和致灾因子强度下 ,脆弱性强 ,灾情重。     

CHARACTERISTICS OF ENVIRONMENTAL AND CLIMATE CHANGE IN CHANGJIANG DELTA AND ITS POSSIBLE MECHANISM*

Characteristics of climate change in the Changjiang Delta were analyzed based on the annual mean meteorological data since 1961,including air temperature,maximum and minimum air temperature,precipitation,sunshine duration and visibility at 48 stations in that area(southern Jiangsu and northern Zhejiang),and its adjacent areas(northern Jiangsu,eastern Anhui and southern Zhejiang),together with the environmental data.The results indicate that it is getting warmer in the Changjiang Delta and cooler in adjacent areas,thus the Changjiang Delta becomes a big heat island,containing many little heat islands consisting of central cities,in which Shanghai City is the strongest heat island.The intensity of heat islands enhances as economic development goes up.From the year 1978.the beginning year of reform and opening policy,to the year 1997,the intensity of big heat island of Changjiang Delta has increased 0.5℃ and Shanghai heat island increased 0.8℃.However.since 1978 the constituents of SO₂,NO_x and TSP(total suspended particles)in the atmosphere,no matter whether in the Changjiang Delta or in the adjacent areas,have all increased,but pH values of precipitation decreased.In the meantime,both sunshine duration and visibility are also decreased,indicating that there exists a mechanism for climate cooling in these areas.Our analyses show that the mechanism for climate warming in the Changjiang Delta may be associated with heating increase caused by,economic development and increasing energy consumption.It is estimated that up to 1997 the intensity of warming caused by this mechanism in the Changjiang Delta has reached 0.8-0.9℃,about 4-4.5 times as large as the mean values before 1978.Since then,the increase rate has become 0. 035℃/a for the Changjiang Delta.It has reached 1.3℃ for Shanghai in 1997,about 12-13 times as large as the mean values before 1978.This is a rough estimation of increasing energy consumption rate caused by economic development.     

绿洲演变及其调控因素初析

绿洲是荒漠区适宜多种生物共同生息繁衍的地域。它通过人为干扰、气候波动和构造活动等因素的变化调控而发生演变。构造活动对绿洲演变的影响具有空间差异性和时间滞后性;气候波动则表现为区域相对一致性, 随时间发展的渐变性和过程的复杂性;人为干扰无论是空间上还是时段上都有很强的局限性, 但其发展迅速和时空不稳定性(社会原因)成为影响绿洲演变的调控因素, 同时也是人工干预绿洲演变, 实施永序管理的重要途径。     

Hydrogeology of a coal-seam gas exploration area, southeastern British Columbia, Canada: Part 1. Groundwater flow systems

Discovery of high contents of methane gas in coals of the Mist Mountain Formation in the Elk River valley, southeastern British Columbia, Canada, has led to increased exploration activity for coal-seam gas (CSG). CSG production requires groundwater abstraction to depressurize the coal beds and to facilitate methane flow to the production wells. Groundwater abstraction will have hydrodynamic effects on the flow system, and an understanding of the groundwater flow system is needed to evaluate these effects. The purpose of this paper is to describe the groundwater flow system in the area by means of a groundwater flow model and interpretation of hydrochemical and isotopic analyses of groundwater and surface water. Groundwater flow for the Weary Creek exploration area is modeled in two vertical sections. The model domains, based on classic upland–lowland conceptual flow models, are approximately 10,000 m long and 4,000 m deep. Each consists of a fixed water-table boundary and no-flow boundaries along the traces of major faults. Steady-state groundwater flow is calibrated to hydraulic-head, streamflow, and groundwater-recharge data. Simulated steady-state velocity fields define regional and local flow components consistent with the conceptual model. The results are consistent with regional trends in δ²H, δ¹⁸O, tritium, and TDS, which define two distinct groundwater groups (A and B) and a third of intermediate composition. An active, shallow, local flow component (group A) is recharged in beds cropping out along subdued ridges; this component discharges as seeps along lower and mid-slope positions in the southern part of the study area. The waters are tritiated, relatively enriched in δ²H and δ¹⁸O, and have low TDS. A deeper regional flow component (group B), which originates at a higher altitude and which discharges to the Elk River valley bottom, is characterized by non-tritiated groundwater with relatively depleted δ²H and δ¹⁸O, and higher TDS. Groundwater contributes less than 10% of the total direct flow to the Elk River, as indicated by flow measurements and by the absence of group A and group B characteristics in the river water. Thus it is hypothesized that groundwater extraction during CSG production will have little impact on the river. The groundwater flow model developed in this work is used in a companion paper to further test this hypothesis. Electronic Publication     

城市生态环境形象设计的生态背景值研究

城市生态背景值包括自然生态背景值与人文生态背景值。城市生态背景值越高,城市生态环境形象建设与管理的成本就越低。通过城市生态背景值的相关因素分析与量化分等,在选择分析的中国14个特大城市中,生态背景值相差甚远。按综合分值分等,第一等空缺,第二等和第三等分别只有广州市和上海市,第四等有7个城市,第五等有3个城市,得分最低的第六等有兰州市和乌鲁木齐市。按自然生态背景值分值划分,第一等空缺,得分最高的第二等只有广州市,最低的第九等是乌鲁木齐市。按人文生态背景值分值划分,第一等空缺,第二等是北京市,其余为第三等和第四等。文章以城市生态背景值为依据,较为详细地分析了广州市何以在较短的时间内由一个"不适合居住"的城市变为"国际花园城市"的原因。     

三江平原气候突变分析

采用累积距平法、J_y参数法和Mann-Kendall法联合检测1955~2000年三江平原气候变化过程中的突变现象,讨论了引发三江平原气候突变的可能原因。分析发现,三江平原年降水量在20世纪60年代发生了减少突变;而三江平原在20世纪70年代和80年代连续两次经历的增温突变,使其气温变化与东北北部平原其它地区明显不同;年日照时数和平均风速的减少突变均发生在20世纪80年代。总体来看,三江平原气候变化在20世纪80年代最明显。     

土体应力-应变关系转型问题分析

通过对土体应力应变试验结果的分析,明确指出了土体普遍存在的应力-应变关系转型现象。提出了按后破坏模量和临界围压两个参数判别土体应力-应变关系转型的方法,对影响土体应力-应变关系转型的因素包括土的类型、围压、初始密度或含水率、排水条件及应力路径等进行了简要分析。最后,对砂土初步提出了一个能反映转型现象的组合应力-应变关系模型的理论框架。     

矿物粉尘溶解行为的电镜研究及其生物化学意义

本文对用Ｇａｎｂｌｅ溶液、有机酸及无机强酸溶解后的矿物粉尘残余物进行了扫描电子显微镜分析。结果表明,矿物纤维粉尘纤维变短、长径比减小、柔性减弱、端部变圆,部分溶解成串珠状;粗大颗粒松散塌陷,表面粗糙度增加;片状粉为碎变细;硅酸盐矿物粉尘具有向以ＳｉＯ２为主要成分的纳米级近球形颗粒转化的趋势。故提出在纳米级别上研究粉尘致病机理是非常有价值的。