Environmental geology in loess areas of China   总被引：2，自引：0，他引：2  

Sun Jianzhong 《Environmental Geology》1988,12(1):49-61

There are several unfavorable geological hazards in the loess area of China. The major purposes of environmental geology studies in this region are to expound the causes of these hazards and to determine treatments. Geological hazards include endemic diseases, depletion of groundwater, land subsidence, ground fissures, soil erosion, and collapsibility of loess. This article is a summary of studies regarding these hazards. Keshan disease and Kaschin-Beck disease, for example, can be prevented and cured by adding selenates to table salt. Ponds can be constructed on the loess plateau and dikes around farmlands to collect rainfall to recharge groundwater resources. Excess extraction of groundwater is the major cause of land subsidence. Ground fissures in Xi'an are primarily caused by tectonics, but over-extraction of ground-water strengthens its activity. Observation stations should be established in order to forecast and prevent landslides. Planting trees in a regional shelterbelt is the primary measure necessary to prevent soil erosion. As a result of these geological studies, valuable experience in preventing collapse of loess in China has been gained.  相似文献   

大气中一类非线性方程的非线性波解及周期的近似计算法     

何建中  潘益农 《热带气象学报》1994,10(4):369-373

大气中许多模式可化为Ｆ＇＇＝ＡＦ／Ｆ＋Ｂ（ＡＢ≠０）一类非线性常微分方程。利用常微分方程定性理论说明了该方程存在非线性波解，讨论了其周期的计算问题，并求得了波解及其周期的近似表达式。  相似文献   

Topography and the non-linear Rossby wave in the zonal shear basic flow     

He Jianzhong 《大气科学进展》1993,10(2):233-242

Under semi geostropical approximation, by means or phase angle function the non-linear ordinary differential equation is derived involving topography and zonal shear basic flow. Conditions for the existence of limited amplitude periodical and isolated wave solutions are directly obtained based on the qualitative theory of the ordinary differentical equation. Analysis is thus made of the influence of topography and zonal shear flow on the existence of wave solution. Finally, explicit wave solutions are determined by function approaching with the result that topogra-phy and zonal shear flow affect not only the existence but also the form of waves, indicating the non-linear features of waves and the effect of topography and shear basic flow on undulation.  相似文献   

纬向切变基流中的非线性Rossby波     

何建中  郭品文 《高原气象》1993,12(4):361-366

本文在半地转近似下讨论了纬向切变基流中的非线性正压Ｒｏｓｓｂｙ波，给出了存在波解的切变基流条件。  相似文献   

内蒙古呼盟地区地震活动的基本特征     

徐建德  杨毅  张建中 《东北地震研究》1993,(1)

通过对内蒙古呼盟地区地震活动的研究,认为呼盟地区震中分布较稳定;存在20年左右地震活动周期;震源机制两节面分布相对比较稳定,P、T轴近水平向;地震破裂是以水平滑动为主。将来呼盟地区的地震活动主体地区为博克图、满洲里一带,震级为5级左右。  相似文献   

四川紫色水稻土氧化铁的分异     

徐建忠 《山地学报》1993,(4)

以岷江冲积物、黄壤残积物发育成的水稻土为对照,研究了紫色砂岩泥岩母质发育成的紫色水稻土氧化铁的形态及其含量和转化。揭示了紫色水稻土具有无定形铁含量,铁活化度较高,氧化铁的转化作用较弱等独特的发生特性。  相似文献   

用油田压裂资料估算应力值     

刘建中  李自强 《地震研究》1990,13(3):298-307

本文比较了从油田压裂资料获得的应力值与专门的水压致裂应力测量结果。研究结果表明,前者的最小水平主应力可以和后者的精度相当,最大水平主应力的精度略低。以长庆油田岭261—2井1985年11月15日实际压裂记录结果和吉林油田东33—35井的压裂记录为例,提出了处理油田资料的方法,给出了相应的处理结果  相似文献   

对中国大陆地壳上部应力状态的讨论     

刘建中 《地震研究》1991,14(3):257-264

本文从走滑型断层活动所应具备的应力条件出发,讨论了走滑型断层活动区的水平主应力的上限和下限。经与现有的绝对应力测值对比,发现3000米以上深度,仅有那些有明显垂直运动的地区的应力值可能超出这个界限。3000米以下深度,实测应力值向所给出的界限内集中。本文所给出的水平应力界限可以做为对深部水平应力值的一种估计。  相似文献   

Determination of kolmogorov entropy of chaotic attractor included in one—dimensional time series of meteorological data     

Yan Shaojin  Peng Yongqing  Wang Jianzhong 《大气科学进展》1991,8(2):243-250

The 1970-1985 day to day averaged pressure dataset of Shanghai and the extension method in phase space are used to calculate the correlation dimension D and the second-order Renyi entropy K2 of the approximation of Kolmogorov’s entropy, the fractional dimension D = 7.7~7.9 and the positive value K2 ≈ 0.1 are obtained. This shows that the attractor for the short-term weather evolution in the monsoon region of China exhibits a chaotic mo-tion. The estimate of K2 yields a predictable time scale of about ten days. This result is in agreement with that ob-tained earlier by the dynamic-statistical approach.The effects of the lag time τ on the estimate of D and K2 are investigated. The results show that D and K2 are convergent with respect to τ. The day to day averaged pressure series used in this paper are treated for the extensive phase space with τ = 5, the coordinate components are independent of each other; therefore, the dynamical character quantities of the system are stable and reliable.  相似文献   

东亚地区天气吸引子特征的研究     

王建中  彭永清 《南京气象学院学报》1994,17(1):86-92

利用东亚地区１１个有代表性测站（１９７９－１９８８年）连续１０年的５００ｈＰａ逐日位势高度时间序列，全面计算了它们的浑沌特征量。结果表明，各测站相应的关联维数都是分数；完整的Ｌｙａｐｕｎｏｖ指数谱中，不仅都有正值、零和负值，而且Ｌｙａｐｕｎｏｖ指数之和都小于零。因此，从整体来看，相应于东亚地区天气尺度的吸引子是由一个有限窨支撑起来的。东亚地区的天气吸引子所显示的系统平均Ｋｏｌｍｏｇｏｌｏｖ熵约为０  相似文献