Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood

The Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m³. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.     

High-resolution sedimentary record of lead in the coastal mud of the East China Sea in the past one hundred and fifty years

In the East China Sea （ECS）, there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence （XRF） techniques and Thermal Ionization Mass Spectrometry （TIMS） were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the ＂Reform and Open Policy＂ in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River （Yangtze River） catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition.     

河南嵩山地区新元古界何家窑组微亮晶脉特征、成因及地质意义探讨

在河南嵩山地区青白口系何家窑组中可识别出一个碳酸盐岩微亮晶脉集中的层位，笔者等结合微亮晶脉自身的特征、成分和伴生的地震引起的其他变形特征，以及通过显微镜和核磁共聚焦显微镜下的微相研究，认为嵩山地区板状微亮晶脉与华北块体东缘胶辽徐淮地区的泥晶脉特征一致，是由地震液化形成的产物，该层位代表了一个地震活跃期。同处华北块体南缘的豫西鲁山和陕西南部相对应的青白口系层位（洛峪口组和巡检司组）也发现了同期的地震记录。笔者认为嵩山地区微亮晶脉的出现应与华北块体南缘构造事件相关联。     

On the nonlinear response of lower stratospheric ozone to NOx and ClOx perturbations for different CH4 sources

The impact of sulfate aerosol, ClOx and NOx perturbations for two different magnitudes of CH4 sources on lower stratospheric ozone is studied by using a heterogeneous chemical system that consists of 19 species belonging to 5 chemical families （oxygen, hydrogen, nitrogen, chlorine and carbon）. The results show that the present modeled photochemical system can present several different solutions, for instance, periodic states and multi-equilibrium states appearing in turn under certain parameter domains, through chlorine chemistry and nitrogen chemistry together with sulfate aerosol as well as the increasing magnitude of CH4 sources. The existence of catastrophic transitions could produce a dramatic reduction in the ozone concentration with the increase of external sources.     

常熟地倾斜观测突跳的深入分析

通过对常熟SQ-70石英丝倾斜仪1996~2005年NS向观测出现的几次显著突跳事件进行深入分析,对地震预报实践中给出的判定意见进行了回顾和反思,同时讨论了该仪器年变幅和M2波潮汐因子的变化,对今后的日常地震预报有较好的参考价值。     

国内震积岩研究现状

地震是一种灾害性的地质事件。震积岩是在地层中具有古地震事件纪录的一类岩石的总称。对其研究可为地壳构造演化提供动力学解释。在地震过程中,震积作用可以形成特殊的标志性特征:如震动液化泥晶脉;微褶皱;层内阶梯状断层;自碎角砾岩(震塌岩);液化均一层等。本文综述了国内学者建立的几种陆相和海相震积岩序列:如碳酸盐岩振动液化地震序列(海相序列);大陆边缘震积岩序列;萨布哈震积岩序列(海陆过渡带序列);陆相碎屑岩地震液化序列(陆相序列)。同时,结合国内学者的研究成果,建立了由震积岩、海啸岩和震浊积岩组成的四种地震沉积组合;并指出了震积岩在构造演化解释、石油储层地质及全球古地震节律方面的研究意义。     

无人机在重大地质灾害应急调查中的应用

传统的地质灾害应急调查受限于地形、天气等外界条件,不能快速全面地获取灾害的详细信息,而无人机具有灵活性强、时效性高和不受复杂地形影响等特点,在地质灾害应急调查中有独特的优势。本文以“6·24”新磨村滑坡和“10·11”白格滑坡为例,阐述了无人机数据获取及处理流程,重点介绍了无人机获取的数字地形产品在地质灾害精确描述、定性及定量分析中的应用。结果表明：无人机摄影测量技术为重大地质灾害应急调查提供了更加科学高效的现场影像采集和遥感成果处理及应用方案,为应急救灾工作的顺利实施及分析研判提供了重要数据支撑,科学有效地保证了现场施工救援人员的安全。     

基于超熵理论的泥石流危险性模糊综合评判

泥石流灾害往往造成巨大经济损失,但由于其影响因素众多,如何合理进行危险性评判一直是研究的焦点问题.本文以研究项目为依托,选择泥石流流域沟谷的纵剖面形态指数作为流域的地貌特征指标,用超熵理论量化泥石流流域地貌系统的稳定性与演化趋势,并借助于模糊综合评判手段,对泥石流危险性进行评价.评判结果表明:该方法的评价结果与实际较为接近,为泥石流流域系统的演化趋势预测以及危险性等级划分提供了良好的分析方法.     

事件地层学与地外灾变事件

从P∈—∈,P—T等地层界线上的特征岩石、古生物大规模灭绝和Ir及ξ~(13)C的异常等研究表明,与K—R界线一样,在这些界线上也可能存在有地外灾变事件。同时文中提出了界线灾变事件、界线灾变期、界线灾变环境、界线层、界线粘土层、梅树村地质事件等与研究事件地层学有关的一系列新概念。     

A swallow-tail type catastrophic model of earthquake process

（殷有泉）（杜静）Ａｓｗａｌｌｏｗ－ｔａｉｌｔｙｐｅｃａｔａｓｔｒｏｐｈｉｃｍｏｄｅｌｏｆｅａｒｔｈｑｕａｋｅｐｒｏｃｅｓｓ￥Ｙｏｕ－ＱｕａｎＹＩＮａｎｄＪｉｎｇＤＵ（ＰｅｋｉｎｇＵｎｉｖｅｒｓｄｙ，Ｂｅｉｊｉｎｇ１００８７１，Ｃｈｉｎａ）（Ｎｏｒｔ...