Effects of differential hillslope‐scale water retention characteristics on rainfall–runoff response at the Landscape Evolution Observatory

Hillslopes turn precipitation into runoff and thus exert important controls on various Earth system processes. It remains difficult to collect reliable data necessary for understanding and modeling these Earth system processes in real catchments. To overcome this problem, controlled experiments are being conducted at the Landscape Evolution Observatory at Biosphere 2, The University of Arizona. Previous experiments have revealed differences in hydrological response between 2 landscapes within Landscape Evolution Observatory, even though both landscapes were designed to be identical. In an attempt to discover where the observed differences stem from, we use a fully 3‐dimensional hydrological model (CATchment HYdrology) to show the effect of soil water retention characteristics and saturated hydraulic conductivity on the hydrological response of these 2 hillslopes. We also show that soil water retention characteristics can be derived at hillslope scale from experimental observations of soil moisture and matric potential. It is found that differences in soil packing between the 2 landscapes may be responsible for the observed differences in hydrological response. This modeling study also suggests that soil water retention characteristics and saturated hydraulic conductivity have a profound effect on rainfall–runoff processes at hillslope scale and that parametrization of a single hillslope may be a promising step in modeling rainfall–runoff response in real catchments.     

基于信息扩散方法的中国西北地区春季沙尘暴灾害风险分析

通过收集大量沙尘暴灾情资料,整理出我国西北地区春季沙尘暴造成的经济损失及农业损失数据,采用基于信息扩散理论的风险评估方法对因灾造成的经济和农业损失风险分别进行了分析.结果表明:①在春季沙尘暴发生日数总体减少的气候背景下,沙尘暴造成的经济和农业损失均呈现出上升的趋势.②经济损失风险高值区主要分布在阿拉善、锡林郭勒、塔里木、阿勒泰、塔城及吐鲁番地区.农业损失风险高值区主要分布在吐鲁番、阿克苏、和田、瓜州、阿拉善地区.     

Mantle Input to the Crust in Southern Gangdese, Tibet, during the Cenozoic: Zircon Hf Isotopic Evidence

The Quxu (曲水) complex is a typical Intrusive among the Gangdese batholiths. Two sets of samples collected from the Mianjiang (棉将) and Niedang (聂当) villages in Quxu County, Including gabbro, mafic micro-enclaves (MME), and granodiorites in each set, were well dated in a previous SHRIMP zircon U-Pb analysis (47-51 Ma). In this article, the same zircons of the 6 samples were ap-plied for LA ICP-MS Hf isotopic analysis. The total of 6 samples yields 176Hf/177Hf ratio ranging from 0.282 921 to 0.283 159, corresponding to εHf(t) values of 6.3-14.7. Their Hf depleted-mantle modal ages (TDM) are in the range of 137-555 Ma, and the zircon Hf isotope crustal model ages (TDMC) range from 178 to 718 Ma. The mantle-like high and positive εHf(t) values in these samples suggest a mantle-dominated input of the juvenile source regions from which the bathollth originated. The large varia-tions in εHf(t) values, up to 5-e unit among zircons within a single rock and up to 15-e unit among zir-cons from the 6 samples, further suggest the presence of a magma mixing event during the time of magma generation. We suggest that the crustal end-member involved in the magma mixing is likely from the ancient basement within the Lhasa terrane itself. The zircon Hf isotopic compositions further suggest that magma mixing and magma underplating at about 50 Ma may have played an important role in creating the crust of the southern Tibetan plateau.     

水下冲孔灌注桩在工程中的应用

分析水下冲孔灌注桩在地下水较为丰富,同时穿越流沙层,圆砾混卵石层等复杂地质条件施工中的质量控制及桩基方案的应用,,并对冲孔灌注桩轴线尺寸容易发生偏位的质量通病和泥浆排放是城市桩基文明施工的难题提出了有效的治理方案,实践证明桩型的选用和施工质量控制方法是正确的,也得到了明显的效果。     

西藏南部二叠纪和早白垩世构造岩浆作用与特提斯演化:新观点

西藏高原前新生代时期的特提斯演化和新生代时期的高原隆升历史是西藏高原基础地质研究中两个长期被关注的重要科学问题,但迄今对西藏高原自身的物质组成和前新生代演化历史的认知程度仍然较低,直接限制了对新生代时期西藏高原隆升历史的更深入研究。新的地质和地球化学资料显示早—中二叠世时俯冲背景和伸展背景共存于现今的冈底斯带和喜马拉雅带,中二叠世末期(大约263Ma)侵位的皮康过铝质S型花岗岩以及同期发生的松多榴辉岩的高压变质作用和区域性角度不整合指示现今的冈底斯弧背断隆带在那时经历了同碰撞造山事件。中生代岩浆岩锆石U-Pb年龄和Hf同位素成分表明,冈底斯弧背断隆带和中冈底斯带存在以古元古代甚至太古宙物质为特征的古老基底物质,而北冈底斯带和南冈底斯则分别以中—新元古代新生地壳和显生宙新生地壳为特征。已有高质量年龄数据和锆石Hf同位素指示冈底斯带中北部地区在大约110Ma发生了带状岩浆大爆发并伴随着幔源物质显著增加。新的可靠的锆石U-Pb年龄指示喜马拉雅带东部措美(Comei)地区大面积出露的白垩纪火成岩侵位于132Ma左右,代表了新近在藏南和澳大利亚南西部识别出的经历了强烈变形和深位侵蚀的Comei-Bunbury大火成岩省的残余。以这些新资料为基础,讨论了西藏南部的晚古生代—中生代构造岩浆演化历史和特提斯演化过程。     

Analysis of the ore-controlling structure of the Shihu gold deposit, Hebei Province and deep-seated ore-prospecting prediction

Under the guidance of the theory of mantle-branch structure-associated metallogenesis and on the basis of the geological characteristics, analysis of the ore-forming and ore-controlling structures, the geochemical characteristics of metallogenesis, the source of ore-forming materials, changes in the physical and chemical conditions of metallogenesis, changes in the vertical width of ore veins, and changes in gold grade of the Shihu gold deposit, the mechanism of its metallogenesis was discussed and the rules of vertical variation of ore veins were summarized in this study. It is pointed out that the orebodies under exploitation at present time should be in the middle and upper portions of gold veins in the Shihu gold mining district. Particularly on the basis of the characteristics of mantle-branch structure-associated metallogenesis, it is indicated that metallogenesis is controlled mainly by such ore-forming conditions as temperature and pressure. Deep-seated ore-forming fluids are characterized mainly by injection and precipitation. So the vein bodies in the adjacent metallogenic structures are of obvious comparability, and there would be great prospects for ore search both at depth and in the periphery of the Shihu gold deposit. Therefore, ore prospecting should be strengthened both at depth and in the peripheries.     

多普勒雷达径向散度在迎风坡降水中的应用

以太行山东部3次迎风坡降水过程为例,分析了由多普勒雷达原始资料计算得到的径向辐合与迎风坡降水分布的关系:迎风坡降水大值区落在临近径向的辐合大值区的弱辐合区内,且降水中心落在正径向速度开始减小的边界同NE风急流相交的位置。连续分布的径向辐合越强,降水越强。同时以2004年7月11—12日过程为例说明单站径向辐合和降水率的关系:径向辐合越强,降水越强,且径向辐合变化超前于降水率变化1h以上;径向辐合持续减弱3h以上,降水率减小,直至结束。径向散度对迎风坡区域的降水预报有很好的指示作用:综合分析区域径向辐合分布和单站径向辐合随时间的变化,可以预测迎风坡降水的落区、发展及生消。     

一次雨雪的回波演变及大气结构特征

利用多普勒天气雷达和探空资料,对2009年3月2日南京的雨雪过程进行了研究,分析了雨雪发展的不同阶段,基本反射率场、基本速度场、基本谱宽场、VWP廓线以及大气要素垂直剖面图的演变特征,分析显示:(1)降雪过程的回波分布连续、具有丝缕状纹理,强度比降雨弱。(2)速度场西北方向有逆风区出现,逆风区持续期间降雪稳定、持续。(3)利用探空资料绘制的大气风矢与位温剖面图可较细致地分析雨雪天气的大气垂直结构特征。(4)雨雪天气过程和大气层结密切相关,K指数、沙氏指数及sθe850-500与雨雪天气的演变有着较好的对应关系。     

2007年8月2日郑州大暴雨过程分析

利用探空资料、Tbb资料及郑州新一代天气雷达产品等,对2007年8月2日发生在郑州市的短时大暴雨过程进行了分析,结果表明:此次郑州短时大暴雨在高空低槽和中低层低涡、切变线共同影响的有利大尺度环境条件下,产生在高温高湿的辐合中心,上干冷下暖湿的对流性不稳定大气层结为此次短时大暴雨提供了大量的位势不稳定能量;此次短时大暴雨是超级单体风暴产生的,新一代天气雷达产品中基本反射率和径向速度产品都具有明显特征;卫星云图上Tbb低值区及强对流云团与强降水中心相对应。     

山东省气象部门公务卡改革

文章通过对山东省气象部门实施公务卡改革背景和现状的阐述,分析了实施公务卡改革的优势及运行过程中存在的问题,并对今后进一步提高公务卡的使用效率,充分发挥公务卡在财务管理工作中的重要作用提出了建议。