Application of a simple headcut advance model for gullies

Gully erosion begins in streambanks and uplands as a consequence of adjustments in driving forces on the landscape imposed by changes in land use or climate. The deleterious effects of gullies worldwide have led to many site‐specific studies of gully form and function. In the continental United States, gully erosion in agricultural land has destroyed valuable farmland yet, prediction of gully processes remains problematic on a national scale. This research has proposed a simple method to predict gully headcut advance. When combined with SWAT hydrologic flow routines, the model predicted gully headcut advance with reasonable accuracy on a daily time step for time periods exceeding two decades. The model was tested in two distinct land resource areas of the United States with differing climate, soils, cover and drainage. The inputs for the headcut model have been kept simple as the model will be applied over large areas. Model inputs consist of headcut height, headcut resistance (based on soil erodibility and a root‐cover factor), and daily flow. The model is compared with an annual time step model used in assessment of headcut advance and appears to offer a better way to assess gully headcut advance. Copyright © 2017 John Wiley & Sons, Ltd.     

Advance in application of regional climate models in China

Regional climate models have become the powerful tools for simulating regional climate and its change process and have been widely used in China. Using regional climate models, some research results have been obtained on the following aspects： 1） the numerical simulation of East Asian monsoon climate, including exceptional monsoon precipitation, summer precipitation distribution, East Asian circulation, multi-year climate average condition, summer rain belt and so on; 2） the simulation of arid climate of the western China, including thermal effect of the Qinghal-Tibet Plateau, the plateau precipitation in the Qilian Mountains; and the impacts of greenhouse effects （CO2 doubling） upon climate in the western China; and 3） the simulation of the climate effect of underlying surface changes, including the effect of soil on climate formation, the influence of terrain on precipitation, the effect of regional soil degradation on regional climate, the effect of various underlying surfaces on regional climate, the effect of land-sea contrast on the climate formulation, the influence of snow cover over the plateau regions on the regional climate, the effect of vegetation changes on the regional climate, etc. In the process of application of regional climate models, the preferences of the models are improved so that better simulation results are gotten. At last, some suggestions are made about the application of regional climate models in regional climate research in the future.     

海洋植物组织和细胞培养研究进展

对海藻组织和细胞培养研究进行了综述。认为我国在该领域的研究起步晚、人员少,但在经济海藻应用研究如紫菜体细胞育苗上具有国际领先水平。为促进海藻组织和细胞培养技术的产业化,应加强藻类组织培养工作者与高等植物组织培养工作者之间的交流和合作,以组织培养技术中较为成熟的离体快繁为突破口,进行市场急需商品苗的快速生产。利用海藻组织和细胞培养进行次生物质合成和特殊药物转化的研究亦具有潜在的应用价值。     

南海现代海平面变化研究的进展

本文根据笔者近年对广东海平面变化的研究,并参考前人的研究结果,对南海现代海平面研究的进展进行了较系统的评述.认为数十年来南海相对海平面总体上呈上升趋势,上升速率一般小于2.5mm/a.1.8mm/a或1.9mm/a可以近似地作为绝对海平面上升速率.预测2030年或2025年相对海平面上升幅度为20～25cm.     

加强深层次科学研究，使青藏高原地质调查的成果再上一台阶——大陆动力学实验室青藏高原研究的最新进展（代序）

近年来对青藏高原拉萨地体中超高压变质带的发现,北部与南部高压/超高压变质作用的深入研究,周缘造山带崛起时限和机制的初步查明,大型走滑断裂的年代学、运动学、动力学和定量研究的进展,以及雅鲁藏布江缝合带中罗布莎地幔岩新矿物研究的突破,说明要使青藏高原地质调查成果再上一台阶,必须加强深层次的科学研究。     

Stress Changes due to Recent Seismic Events in the Central Apennines (Italy)

The Central Apennines, Italy, are characterized by moderate seismic activity on normal faults, oriented in directions parallel to the Apenninic chain. The subject of this study is the Umbria-Marche Apennines, a segment approximately 200-km long, where three main seismic events occurred in the last three decades. The 1979 Norcia earthquake was a M_w = 5.8 event, taking place at the south end of the considered segment. The 1984 Gubbio earthquake was a M_w = 5.6 event which took place at the north end. The 1997-1998 Colfiorito sequence constituted 8 main shocks with magnitudes M_w between 5 and 6 and epicenters located between the Gubbio and the Norcia earthquake areas. A model made of an elastic half-space is considered, in which the seismic sources are represented by rectangular dislocations which have the appropriate values of source parameters, and in which the static stress field produced by each event is calculated. The analysis of the Coulomb stress change (ΔC) as a function of time shows that the coseismic stress transfer and fault interaction played an important role in the region during the past three decades: 7 earthquakes of the 9 considered took place where ΔC>0. Such an interaction has been confirmed by the analysis of the aftershocks in the Colfiorito zone post September 26, 1997: about the 61% of the aftershocks considered took place where ΔC>0. The comparison between the ΔC^s due to the coseismic stress transfer and the rate ΔĊ^t due to the tectonic stress allows us to quantify the time advance of the earthquakes. The ΔC^s pattern shows positive values in two areas that can be regarded as historical seismic gaps.     

宁夏沙尘暴天气研究进展

概括地分析了宁夏沙尘暴天气的地理分布与时空演变特征、形成机理与成灾规律,以及沙尘暴与生态环境等方面的研究成果。 总结性地分析了宁夏中北部沙尘暴多发区生态退化、土地荒漠化与强沙尘暴间的相互关系等,取得了阶段性进展;同时也介绍了利用多源资料及相关科研成果,建立适合宁夏中北部地区气候特征的沙尘暴发生频率定量化模型等,以期对以后沙尘暴的更深入研究有所借鉴和帮助。     

我国地震监测预报研究的主要科学进展

回顾和总结了1966年邢台地震以来我国地震监测预报研究的主要科学进展,并将其归纳为建立了4个方面的基础,即: 地震预测预报的多学科观测基础;获取了一批中强以上乃至大地震资料的震例基础;建立了经验性预测方法和判据的经验预报基础;初步探索了地震孕育发生的地震预报理论基础。文中还阐述了我国20世纪90年代在长期预报、中期预报、短临预报的预报效能。     

中国煤层气地质研究进展与述评

基于对国内近年来有代表性的学术论著的研究分析,从煤层气生成演化与运移效应、煤储层特性及其预测理论、煤层气成藏动力学条件及数值模拟、煤层气成藏类型及区域聚集规律等方面,评述了我国煤层气基础地质近年来研究进展,并指出煤层气超临界吸附效应、煤层气能量平衡系统与聚散机制、煤层气有效资源评价理论与方法、煤储层渗透率构造-采动控制效应、含煤层气系统有效失衡叠加场效应等是我国煤层气地质近期研究的发展趋势。     

扬子海盆奥陶纪末介壳动物群的分布及其古地理意义

通过奥陶纪末扬子海盆介壳动物群生态组合的划分, 并结合介壳动物群产出的岩性特征的研究, 分析了当时海盆内部的沉积分异特点: 扬子海盆中部, 水体相对较深, 为浅海较深水盆地, 指示的生态域 > BA4- 5;到海盆东部水体逐渐变浅, 生态域以BA4- 5为主; 海盆西部水体变得更浅, 生态域以 < BA3为主.此外, 将海盆划分为中部浅海深水黑色硅质页岩盆地、东、西部浅海碎屑岩和浅海碳酸岩-碎屑岩沉积盆地.从南往北, 进一步对以上3个沉积区进行了水体深浅变化的探讨, 并且认为: 海盆中部, 由西南往东北方向, 水体逐渐变深, 沉积中心位于湖北、湘中及湘北部分地区(桃园—安化一带); 海盆西部和东部, 从南往北, 水体均由浅变深(在海盆西部, 黔北生态域 < BA3, 川中至川东 < BA3, 川北和陕南为BA4;在海盆东部, 浙江桐庐、常山一带 < BA3, 安徽泾县和南京等地≥BA4- 5).此外, 根据生物群和岩性的空间变化, 认为扬子海盆以北面临大洋或洋盆.