Research on Climate Feedback of Human Water Use and Its Impact on Terrestrial Water Cycles —Advances and Challenges

The terrestrial water cycle is the mutual transformation of surface and near-surface water, which controls the supply of fresh water resources. It is affected by human activities, solar radiation and gravity, as well as climate and environmental conditions. Inter-basin water transfer, irrigation, crop cultivation and harvesting, exploitation of groundwater water and other human activities lead to the change of spatial and temporal distribution of soil moisture, the underground water level, surface albedo, surface evaporation, as well as water and energy exchange between land surface and atmosphere. Human water use generates important feedback on the climate and changes the processes of the terrestrial water cycle significantly. The spatial and temporal distribution of precipitation in China is uneven. In addition, human activities further exacerbate the fragility of water resources and the contradiction between supply and demand, posing a serious challenge to the sustainable development of social economy. Therefore, understanding the laws and mechanisms of terrestrial water cycle change is very important for water resources utilization and human sustainable development. From the perspective of climate change and human activities, this paper summarized the impact of human activities on terrestrial water cycle and the progress of climate feedback research. It is urgent to consider the evolution of terrestrial water cycle and its climate under the dual impact of natural and human activities, and develop the large-scale land surface hydrological models and climate models with human water use, crop planting and irrigation, lateral groundwater flow. From the perspective of a fully coupled system, we need quantitatively to assess the climate feedback of human water use and its impact on the terrestrial water cycle process, and to explore its mechanism. We need to distinguish the contribution of human water activities and global climate change to the evolution of terrestrial water cycle in the context of climate change, and to propose water resources management strategies to address climate change.     

郴县新田岭钨矿床地质特征

郴县新田岭白钨矿床，是一个大型─超大型矿床。储量巨大的Ⅰ＿５、Ⅰ＿（３０）和Ⅱ＿（２３）号主矿体，皆赋存在燕山早期花岗岩与石磴子组灰岩接触带的凹陷部位，三个主矿体的钨金属量，占矿区总储量的９０％以上。矿床矿物成分、结构构造和围岩蚀变均较复杂，其中晚期复杂矽卡岩与钨矿化关系密切。本矿床的形成，受成矿岩体、有利的围岩和接触带及层间破碎带控制，矿床的成生，经历了两个成矿期５个成矿阶段。矿床成因属气化─高温热液矿床。     

天津雾和霾自动观测与人工观测的对比评估

为适应地面气象观测业务调整方向,提高新型自动气象站观测资料的质量及可用性,研究中对天津地区10个地面气象站1951—2014年历年2月人工观测及2014年2月自动观测和人工观测的轻雾、雾、霾现象进行对比评估。结果表明:天津地区历年2月轻雾的平均日数为10 d,雾和霾均为2 d,轻雾和霾同期出现的日数占有天气现象的7.4%,而雾和霾同期出现日数仅占0.7%;平行观测期的对比分析得到人工观测轻雾日数比自动观测多11 d,雾日数和霾日数均比自动观测少6 d,其中,轻雾和雾的判别差异集中出现在每日08:00(北京时,下同),霾则基本出现在每日08:00,14:00,17:00,20:00;通过对比自动观测和人工观测的能见度数据发现,二者相对偏差达25.1%,能见度小于15.0 km时,自动观测的能见度有60%~76%数值偏小,特别是08:00和20:00, 因此,在相对湿度满足条件的情况下,能见度的判别误差是导致自动观测与人工观测轻雾、雾、霾现象判别差异的重要原因。     

Mapping Potential Groundwater‐Dependent Ecosystems for Sustainable Management

Ecosystems which rely on either the surface expression or subsurface presence of groundwater are known as groundwater‐dependent ecosystems (GDEs). A comprehensive inventory of GDE locations at an appropriate management scale is a necessary first‐step for sustainable management of supporting aquifers; however, this information is unavailable for most areas of concern. To address this gap, this study created a two‐step algorithm which analyzed existing geospatial and remote sensing data to identify potential GDEs at both state/province and aquifer/basin scales. At the state/province scale, a geospatial information system (GIS) database was constructed for Texas, including climate, topography, hydrology, and ecology data. From these data, a GDE index was calculated, which combined vegetative and hydrological indicators. The results indicated that central Texas, particularly the Edwards Aquifer region, had highest potential to host GDEs. Next, an aquifer/basin scale remote sensing‐based algorithm was created to provide more detailed maps of GDEs in the Edwards Aquifer region. This algorithm used Landsat ETM+ and MODIS images to track the changes of NDVI for each vegetation pixel. The NDVI dynamics were used to identify the vegetation with high potential to use groundwater—such plants remain high NDVI during extended dry periods and also exhibit low seasonal and inter‐annual NDVI changes between dry and wet seasons/years. The results indicated that 8% of natural vegetation was very likely using groundwater. Of the potential GDEs identified, 75% were located on shallow soil averaging 45 cm in depth. The dominant GDE species were live oak, ashe juniper, and mesquite.     

冬奥会保障项目地电阻率台站防雷技术系统设计关键技术

雷电危害是影响地震台站稳定运行的重要因素之一,对台站进行雷电防护具有重要意义。介绍冬奥会保障项目地电阻率台站改造中避雷系统的设计,并重点分析研究地电阻率台站架空线路防雷、地埋线路防雷等关键技术点出现的问题,探讨地电阻率台站综合防雷系统在接地网、供电、综合布线等方面的整体设计,最后设计完成宝昌台防雷技术系统。在此基础上,完成项目全部8个台站的避雷系统方案设计,全面提升冬奥会项目台站的防雷实效。通过计算,在项目深化研究中得到一些新的技术成果:(1)地电阻率台站应尽量将供电及测量线路进行埋地;(2)埋地供电及测量线路应避开接地体10 m以上;(3)仍采用架空线路的台站可以安装相应电流值的信号防雷器。研究成果可供今后全国台站防雷系统建设时参考。     

青藏高原西北部帕米尔东北缘构造地貌与活动构造研究

新生代以来,印度板块与欧亚大陆的碰撞和持续的汇聚在青藏高原西北部的帕米尔地区造成了强烈的陆内变形,形成一系列典型的构造地貌。文章在卫片解译、DEM数据处理的基础上,结合野外地质、地貌观察与测量,对帕米尔东北缘的构造地貌与活动构造特征进行了研究,取得以下认识： 1)在英吉沙地区,通过测量地貌变形面计算出英吉沙背斜隆起高度约为230m,并利用面积平衡法估算出英吉沙背斜的最小构造缩短量约为110m,参考前人的年代学数据计算出英吉沙背斜在中更新世以来的最低隆升速率约为0.23mm/a,最小构造缩短速率约为0.11mm/a; 2)在帕米尔前缘,乌泊尔断裂为一条伴随右旋走滑分量的逆冲断裂,该断裂的右旋走滑作用错断了古近纪地层及流过断裂的河流,通过测量单次地震造成的水系错断量并参考前人研究的该地区大震复发周期约为1000年,估算出该断裂的平均走滑速率为 4.0～6.8mm/a,并推测断裂开始活动的时间大约在 2.2～3.0Ma以前; 3)对喀什地区构造地貌特征的观察与研究表明,明尧勒－喀什背斜和阿图什－踏浪河背斜可能分别为帕米尔东北缘西昆仑山山前冲断带和西南天山山前冲断带的前缘,该地区以西,帕米尔东北缘西昆仑山和西南天山两大构造系统已经发生了碰撞和拼贴。     

华北地台沉积岩型金矿床的找矿勘查意义

冀东地区沉积岩型金矿床主要赋存在中上元古界长城系和蓟县系巨厚钙－镁碳酸盐岩内,金矿化受层间角砾岩带控制。相比之下,内蒙古中西部沉积岩型金矿床主要产出在上元古界青白不钙质粉砂岩和板岩内,矿父母产状受层间构造破碎带控制。尽管上述金矿床的成矿环境、赋矿围岩和成矿时代存在一定差别,但是它们均以埋藏浅、规模大、物质组分简单和易选冶为特点。为突出这两类金矿床的区域性特征,前者命为“长城式”,后者则确定为“阿拉     

古尔班通古特沙漠蚀余沙丘的发现及其意义

我国贺兰山以东的沙漠多以流动沙丘为主,但新疆北部准噶尔盆地在年降水量不足150ｍｍ的古尔班通古特沙漠则以固定、半固定沙丘为主。因而研究这一沙漠的“准稳定态”,对我国沙漠理论的研究和风沙灾害治理、土地沙漠化防治均有重要意义。     

扬子台地西南部奥陶系宝塔组底部含鲕绿泥石灰岩成因意义

对四川省兴文县上奥陶统宝塔组底部含鲕绿泥石灰岩开展成因研究,有助于了解扬子台地西南部同时期的沉积环境演化过程.通过沉积学分析,并辅助以电子探针和扫描电镜等矿物学研究方法,发现富鲕绿泥石鲕粒及球粒为同生期沉积物,共生的生物碎屑组合指示海水为氧化性水体.丰富的微生物相关组构表明同期微生物席发育,且其代谢活动可致使水岩界面附...     

Experimental research and finite element analysis of bridge piers failed in flexure-shear modes

In recent earthquakes, a large number of reinforced concrete （RC） bridges were severely damaged due to mixed flexure-shear failure modes of the bridge piers. An integrated experimental and finite element （FE） analysis study is described in this paper to study the seismic performance of the bridge piers that failed in flexure-shear modes. In the first part, a nonlinear cyclic loading test on six RC bridge piers with circular cross sections is carried out experimentally. The damage states, ductility and energy dissipation parameters, stiffness degradation and shear strength of the piers are studied and compared with each other. The experimental results suggest that all the piers exhibit stable flexural response at displacement ductilities up to four before exhibiting brittle shear failure. The ultimate performance of the piers is dominated by shear capacity due to significant shear cracking, and in some cases, rupturing of spiral bars. In the second part, modeling approaches describing the hysteretic behavior of the piers are investigated by using ANSYS software. A set of models with different parameters is selected and evaluated through comparison with experimental results. The influences of the shear retention coefficients between concrete cracks, the Bauschinger effect in longitudinal reinforcement, the bond-slip relationship between the longitudinal reinforcement and the concrete and the concrete failure surface on the simulated hysteretic curves are discussed. Then, a modified analysis model is presented and its accuracy is verified by comparing the simulated results with experimental ones. This research uses models available in commercial FE codes and is intended for researchers and engineers interested in using ANSYS software to predict the hysteretic behavior of reinforced concrete structures.