静/慢地震研究现状及意义

静/慢地震是地壳能量释放的一种形式,可能消除一个正趋于断裂地带的地震威胁,也可能因为应力的转移而触发一个正常的地震;也有一些学者认为静/慢地震的发生并不在断层闭锁区域,两者的关系不大.对于静/慢地震的危险性尽管分歧较大,然而看法一致的是静/慢地震是地震断裂过程的一个组成部分,在地震成核作用中可能起着重要的作用,静/慢地...     

2010年文山久旱背景下一次全州性降雨天气过程诊断分析

对2010年4月21～23日文山州久旱转大雨过程的环流演变及各种物理量场特征进行诊断分析,结果表明:干旱期文山长期维持"西高东低"环流型,环流形势的调整,尤其是中纬度环流形势向"东高西低"转变,是久旱转雨的必要条件。这次过程也与高空冷槽、低涡切变和不稳定层结(能量)的发展等有关。久旱转雨时,各物理量场的分布与该区域降水相关性很好,具有很明显的指示意义。     

川西坳陷孝泉—丰谷构造带变形特征及成因机制模拟

通过对三叠系不同组段顶面构造图分析和主干地震剖面解释,认为川西坳陷孝泉—丰谷构造带具有走向分带、垂向分层变形特征。该构造带走向上可划分为孝泉、新场、合兴场、丰谷等4排北东东向雁列式滑脱褶皱带,与合兴场—石泉场近南北向背斜构造带近直交;垂向上以雷口坡组内膏盐层为界分上、下两个构造层,上部构造层发育滑脱断层及其相关的褶皱构造,下部构造层产状平缓,断层、褶皱构造不发育。多组平面、剖面模拟实验结果表明:孝泉—丰谷北东东向滑脱褶皱带可能是在龙门山褶皱隆升产生的北西向挤压应力和秦巴山系褶皱隆升产生的近南北向挤压应力联合作用下形成的;合兴场—石泉场近南北向构造带可能是在北西方向的应力单独挤压作用下形成的;雷口坡组内膏盐层在空间上不均衡分布是产生走向分带、垂向分层变形的主控物质因素。     

孤岛馆陶组注水开发储层性质动态变化特征研究

综合利用取心资料、实验室分析化验数据和矿场动态测井资料，研究了孤岛油田低含水期、中高含水期、特高含水期馆陶组砂岩油层岩性、物性、含油性和电性的变化特征。经过长期的注水开发，造成油层泥质含量、碳酸盐含量、含油饱和度和束缚水饱和度降低，平均孔隙直径增大，岩石粒度中值提高，导致渗透率、孔隙度增大。在物性总体增大的同时，孔渗参数的分异度增加；同时，也会由于水敏和速敏的影响使物性变差。声波时差和自然电位、感应电阻率都发生了明显变化，不同岩性的储层参数变化程度有差异，粉砂岩的变化程度小于细砂岩。     

On the winter evolution of snow thermophysical properties over land‐fast first‐year sea ice

The geophysical, thermodynamic and dielectric properties of snow are important state variables that are known to be sensitive to Arctic climate variability and change. Given recent observations of changes in the Arctic physical system (Arctic Climate Impact Assessment, 2004), it is important to focus on the processes that give rise to variability in the horizontal, vertical and temporal dimensions of the life‐history of snow on sea ice. The objectives in this study are to present these ‘state’ variables and to investigate the processes that govern variability in the vertical, horizontal and temporal dimension by using a case study over land‐fast first‐year sea ice for the period December 2003 to June 2004. Results from two sampling areas (thin and thick snowpacks) show that differences in snowpack thickness can substantially change the vertical and temporal evolution of snow properties. During the late fall and early winter (cooling period) we measured no significant changes in the physical properties, except for thin snow‐cover salinity, which decreased throughout the period. Fall‐snow desalination was only observed under thin snowpacks with a rate of ?0·12 ppt day^?1. Significant changes occurred in the late winter and early spring (warming period), especially for snow grain size. Snow grain kinetic growth of 0·25–0·48 mm·day^?1 was measured coincidently with increasing salinity and wetness for both thin and thick snowpacks. Copyright © 2006 John Wiley & Sons, Ltd.     

Reform and teaching quality —Exemplification of regional physical geography

There are a number of factors involved in teaching quality. Among them teaching materials or textbooks are of primary importance, the presentation of which relies first of all on the viewpoint to structure the contents geographically. Whatever branch of geography you are teaching or in pursuit, geographical viewpoint is vitally important. This paper in discussing innovation of geographical education about these institutions with the course of regional physical geography as an example. The higher education of our discipline is in pressing need of innovation and thereby upgrading quality.     

Disciplinary structure and development strategy of physical geography in China

Journal of Geographical Sciences - Physical geography, one of the branches of geography, is the basic discipline of geographic science. And it is the scientific foundation of ecology, environmental...     

Biogeomorphology,quo vadis? On processes,time, and space in biogeomorphology

Biogeomorphology has been expanding as a discipline, due to increased recognition of the role that biology can play in geomorphic processes, as well as due to our increasing capacity to measure and quantify feedback between biological and geomorphological systems. Here, we provide an overview of the growth and status of biogeomorphology. This overview also provides the context for introducing this special issue on biogeomorphology, and specifically examines the thematic domains of biogeomorphological research, methods used, open questions and conundrums, problems encountered, future research directions, and practical applications in management and policy (e.g. nature-based solutions). We find that whilst biogeomorphological studies have a long history, there remain many new and surprising biogeomorphic processes and feedbacks that are only now being identified and quantified. Based on the current state of knowledge, we suggest that linking ecological and geomorphic processes across different spatio-temporal scales emerges as the main research challenge in biogeomorphology, as well as the translation of biogeomorphic knowledge into management approaches to environmental systems. We recommend that future biogeomorphic studies should help to contextualize environmental feedbacks by including the spatio-temporal scales relevant to the organism(s) under investigation, using knowledge of their ecology and size (or metabolic rate). Furthermore, in order to sufficiently understand the ‘engineering’ capacity of organisms, we recommend studying at least the time period bounded by two disturbance events, and recommend to also investigate the geomorphic work done during disturbance events, in order to put estimates of engineering capacity of biota into a wider perspective. Finally, the future seems bright, as increasingly inter-disciplinary and longer-term monitoring are coming to fruition, and we can expect important advances in process understanding across scales and better-informed modelling efforts. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

Generation of realistic synthetic catchments to explore fine continental surface processes

Understanding, analysing, and predicting the erosion mechanisms and sedimentary flows produced by catchments plays a key role in environmental conservation and restoration management and policies. Numerical case-testing studies are generally undertaken to analyse the sensitivity of flood and soil erosion processes to the physical characteristics of catchments. Most analyses are conducted on simple virtual catchments with physical characteristics that, unlike real catchments, are perfectly controlled. Virtual catchments generally correspond to V-shaped valley catchments. However, although these catchments are suitable for methodical analysis of the results, they do not provide a realistic representation of the spatial structures of the landscape and field conditions. They can, therefore, lead to potential modelling errors and can make it difficult to extend or generalize their results. Our proposed method bridges the gap between real and traditional virtual catchments by creating realistic virtual catchments with perfectly controllable physical characteristics. Our approach represents a real alternative to traditional test case procedures and provides a new framework for geomorphological and hydrological communities. It combines a field procedural generation approach, geographic information system processing procedures, and the CAESAR-Lisflood landscape evolution model. We illustrate how each of these components acts in the process of generating virtual catchments. Five physical parameters were adjusted and tested for each virtual catchment: drainage density, hypsometric integral, mean slope of the main channel, granulometry, and land use. One of our virtual catchments is compared with a real catchment and a virtual catchment produced by a standard method. This comparison indicates that our approach can produce more realistic virtual catchments than those produced by more traditional methods, while a high degree of controllability is maintained. This new method of generating virtual catchments therefore offers significant research potential to identify the impacts of the physical characteristics of catchments on hydro-sedimentary dynamics and responses.     

An open web-based module developed to advance data-driven hydrologic process learning

The era of ‘big data’ promises to provide new hydrologic insights, and open web-based platforms are being developed and adopted by the hydrologic science community to harness these datasets and data services. This shift accompanies advances in hydrology education and the growth of web-based hydrology learning modules, but their capacity to utilize emerging open platforms and data services to enhance student learning through data-driven activities remains largely untapped. Given that generic equations may not easily translate into local or regional solutions, teaching students to explore how well models or equations work in particular settings or to answer specific problems using real data is essential. This article introduces an open web-based module developed to advance data-driven hydrologic process learning, targeting upper level undergraduate and early graduate students in hydrology and engineering. The module was developed and deployed on the HydroLearn open educational platform, which provides a formal pedagogical structure for developing effective problem-based learning activities. We found that data-driven learning activities utilizing collaborative open web platforms like CUAHSI HydroShare and JupyterHub to store and run computational notebooks allowed students to access and work with datasets for systems of personal interest and promoted critical evaluation of results and assumptions. Initial student feedback was generally positive, but also highlighted challenges including trouble-shooting and future-proofing difficulties and some resistance to programming and new software. Opportunities to further enhance hydrology learning include better articulating the benefits of coding and open web platforms upfront, incorporating additional user-support tools, and focusing methods and questions on implementing and adapting notebooks to explore fundamental processes rather than tools and syntax. The profound shift in the field of hydrology toward big data, open data services and reproducible research practices requires hydrology instructors to rethink traditional content delivery and focus instruction on harnessing these datasets and practices in the preparation of future hydrologists and engineers.