THE ADVERSE IMPACT OF HUMAN ACTIVITIES ON FLOOD CONTROL IN THE HUAIHE BASIN

LIN~DUCnONTheHuaiheBasinislOCatedbetWeen31"-36"llorthemlahtudeand112"-121"easternlongitude,andcoversatotalareaofabout269,000sq.kin,OfwhichthemountainousandhillyareasocCUPyl/3,theplainsandlow-iringland2/3.ThebasinelicitSsalientphysicalgeographicalfeatllTesasfollowsf(l)Thereisnoobviousmountaindividebe~ntheWatershedoftheriVerandtheYellowforerBasinaswellastheYangtZeRadBasin.MostofthetributariesinthenoalbudoftheHuaiheforertakethesouthdikesOftheYellowherasthedivide.(2)TheriVerbedofthetr…     

1991年太湖地区洪涝灾害评估与人类活动的影响

1991年6、7月间,太湖地区遭受特大洪涝灾害,受灾面积达3309km~2,直接经济损失达106亿元。梅雨暴雨是造成这次洪灾的直接原因,短时间内,降雨量达899mm,为100—200年一遇,超过该地区的承受能力。人类活动对加重灾情亦有着重要影响,包括:围垦与泥沙淤积,使河湖调蓄功能下降;太湖出口河道74.6％被封淤堵死,致使太湖水位达4.79m,超过历史最高记录;圩外面积减少及城市化发展等。治理对策包括充分发挥河湖调蓄功能;合理安排圩外调蓄流量,打通骨干排水河道及城市防洪系统建设等。     

IMPACTS OF FLOOD EVENTS IN COARSE SEDIMENT-PRODUCING AREAS ON CHANNEL SILTATION AND FLUVIAL PROCESS OF THE LOWER YELLOW RIVER

The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened.     

地震灾害评估和灾害数据管理系统(EDMS)的开发——以丽江地震为例(英文)

地震一旦发生,给出一个快速而合理的震害评估,对于减轻地震灾害和灾区重建具有极其重要的意义。最近几年,大量的研究工作试图在GIS平台上建立一个这样的系统以改善和加快震害评估的速度,有的已经得到了实际应用。然而,几乎所有这些研究和开发都是基于城市地区,特别是发达国家的城市地区。而对于发展中国家的乡村地区,由于不具备象发达城市地区那样的基础数据和基础设施,很难把适用于发达的城市地区的类似系统移植过来。此外,尽管同样强度的地震在发达的城市地区造成的损失远大于发展中国家的乡村地区,但地震灾害在乡村地区所造成的损失恢复起来要比在发达的城市地区困难得多。所以,有必要在GIS平台上建立一个适用于乡村地区,特别是发展中国家乡村地区的灾害评估和灾害数据管理系统。本研究的目的就是在GIS平台上建立一个适用于中国西南偏远乡村地区的地震灾害评估和灾害数据管理系统(EDMS)。建立本系统的依据是中国地震局1988年编的《地震现场工作大纲和技术指南》中的“现场地震灾害损失评估方法”。本系统由1)震后快速评估与2)震害数据管理和综合评估2部分组成。选择的范例研究区为丽江地区,使用的基础数据包括云南省特别是丽江专署和丽江县的家庭和人口分布、各     

1993年2月和静5.4级地震震害评估与地震构造

１９９３年２月３日零时５分，和静县哈尔莫敦乡发生５．４级中强地震，震源深度２９ｋｍ，震中烈度达Ⅵ度。地震造成个别房屋倒塌，部分房屋出现不同程度的破坏，地表有十几公里的构造地裂缝，地震造成房屋倒塌和破坏的直接经济损失７２．７万元。     

西湖引水前后氮 , 磷 , 叶绿素 A 含量的年周期变化

研究了杭州西湖引水前后主要湖区水体中的氮、磷、叶绿素a的年周期动态变化。结果表明:外湖等五个湖区的总氮含量在春季和秋季有两个高峰值,与引水前相比变化不大。硝酸盐氮各湖区均在1～4月呈现高峰。各湖区的总磷含量5月开始急剧上升,9月后降至最低;氮、磷在各湖区的年平均含量也略有差异,一般以岳湖和北里湖湖区的含量较高,而三潭内湖和小南湖湖区相对较低。对各湖区水样检测的相关分析表明:总磷和叶绿素a的年周期动态变化密切相关,而可溶性磷与各湖区的叶绿素a含量相关不显著,但其动态变化一致。从西湖水质改善的程度来看,引水工程只是治理西湖的一项重要措施,但不是根本措施,还需进一步加强截污、科学疏挖、控制游船数量等综合治理。     

从第29届国际地质大会看含油气盆地分析的某些进展

总结分析了第２９届国际地质大会上有关含油气盆地分析中某些方面的进展，主要包括：（１）弧后及大陆裂谷盆地、克拉通盆地、前陆盆地以及与走滑作用有关的盆地形成的地球动力学背景及形成机理分析；（２）利用砂岩岩石学和火山岩地球化学特征探讨盆地形成的构造背景及其演化；（３）层序地层学在分析沉积盆地沉积充填特征及历史、识别和预测储集砂体、预测源岩分布及有机质丰度中的应用；（４）盆地发育过程中主要地质作用的数值模拟；（５）油气生成、运移和聚集的数值模拟。     

上海市防震减灾应急决策信息系统-GPS的应用

为了适应上海经济建设高速发展和超大型城市防震减灾工作的需要,建立城市防震减灾应急决策信息系统已成为必然．本文将地理信息系统（GIS）技术应用于上海市防震减灾应急决策信息系统（宝山试点区）,介绍了此系统各功能模块的结构和作用．此系统由７个功能模块组成,即地震地质基本信息、地震灾害快速评估子系统、地震应急决策信息子系统、信息查询、系统维护管理、帮助和退出等．其核心部分是地震灾害快速评估子系统和地震应急决策信息子系统．本文还介绍了彩红外航片遥感技术在上海市防震减灾应急决策信息系统中的应用．     

云南地震重点监视防御区震害异常软弱岩土的调查研究

通过分析云南历史破坏性地震震害异常影响因素,得出第四系软弱土层和新近系禽煤岩层等软弱岩土因素是显著影响云南历史地震震害异常的原因。利用1：20万（中比例尺）地质及水文地质资料,对云南地震重点监视防御区软弱岩土进行调研,得到软弱岩土的分布状况．并初步分析了软弱岩土的分布特征。同时,通过分析对覆盖整个昆明盆地的新生代沉积相作过较详细研究工作的1：5万地质资料,得到昆明盆地软弱土的分布及特征。     

利用地面激光与地质雷达综合探测活断层浅层三维结构——以川西理塘毛垭坝盆地北缘正断层为例

快速获取活断层的高精度微地貌形态和对应的浅层三维结构是揭示活断层浅地表形迹与活动特征的关键。文中综合利用地面三维激光扫描仪和地质雷达技术,以川西理塘地区毛垭坝盆地北缘主边界断裂禾尼段的正断层崖为研究对象,获取了该处正断层错动2期最新地貌面的精确地表垂直位移量和浅层二维地质雷达图像,并初步建立了基于地面三维激光与地质雷达的活断层微地貌精细化三维测量方法,构建了断层崖微地貌的精细三维模型和浅表三维图像,揭示了正断层崖处发育的伸展地堑结构,同时初步实现了断层微地貌地表地下三维数据的一体化融合显示及相互解译。应用结果表明,该方法可以同时快速、高效、无损地获取大范围内的活断层微地貌及浅层结构的多层次、多视觉的空间数据,极大地提高了对活动断层微地貌形态与浅层结构进行快速调查与研究的精度和认识水平,也为更全面地认识和理解活断层的空间分布与变形特征、活动习性和多期古地震遗迹等提供重要的数据和方法支持。因此,对该方法的继续探索和完善,将显著提升和扩展其在活断层定量化和精细化研究中的实用性及应用前景。     

THE DELINEATION OF THREE-DIMENSIONAL SHALLOW GEOMETRY OF ACTIVE FAULT BASED ON TLS AND GPR: A CASE STUDY OF AN NORMAL FAULT ON THE NORTH MARGIN OF MAOYABA BASIN IN LITANG,WESTERN SICHUAN PROVINCE

It is crucial to reveal the surface traces and activity of active faults by obtaining high-precision microtopography and three-dimensional shallow geometry. However, limited by the traditional geological investigation methods in the field and geological condition factors, the measurement method on microtopography and shallow geometry of active fault is badly insufficient. In this study, the TLS and GPR are firstly used comprehensively to delineate the microtopography and shallow geometry of the normal fault scarp on the north margin of Maoyaba Basin in Litang. Firstly, the vertical displacements of two landforms produced by the latest two periods of normal faulting and the two-dimensional GPR profiles are obtained separately. Secondly, the three-dimensional measurement method of active fault based on TLS and GPR is preliminarily established. On this basis, three-dimensional model of fault scarp and three-dimensional images of subsurface geometry are also obtained. These data all reveal a graben structure at normal fault scarps. Thirdly, the fusion and interpretation of three-dimensional data from the surface and subsurface are realized. The study results show:1)the vertical displacements of the T₁ and T₂ terraces by the normal fault movement is 1.4m and 5.7m, the GPR profile shows a typical fault structure and indicates the existence of small graben structure with a maximum width of about 40m in the shallow layer, which further proves that it is a normal fault. 2)the shallow geometry of the normal fault scarp can be more graphically displayed by the three-dimensional radar images, and it also makes the geometry structure of the fault more comprehensive. The precise location and strike of faults F₁ and F₂ on the horizontal surface are also determined in the three-dimensional radar images, which further proves the existence of small graben structure, indicating the extensional deformation characteristics in the subsurface of the fault scarps. Furthermore, the distribution of small graben structure on the surface and subsurface is defined more precisely. 3)the integrated display of microgeomorphology and shallow geometry of normal fault scarp is realized based on the three-dimensional point cloud and GPR data. The fusion of the point cloud and GPR data has obvious advantages, for the spatial structure, morphological and spectral features from the point cloud can improve the recognition and interpretation accuracy of GPR images. The interpreted results of the GPR profiles could minimize the transformation of the surface topography by the external environment at the most extent, restore the original geomorphology, relocate the position and trend of faults on the surface and constrain the width of deformation zones under the surface, the geological structure, and the fault dislocation, etc. In a word, the TLS and GPR can quickly and efficiently provide the spatial data with multi-level and multi-visual for non-destructive inspection of the microgeomorphology and shallow structure for the active fault in a wide range, and for the detection of active fault in the complex geological environments, and it is helpful to improve the accuracy and understanding of the investigation and research on microtopography and shallow geometry of active faults. What's more, it also offers important data and method for more comprehensive identification and understanding of the distribution, deformation features, the behaviors of active faults and multi-period paleoseismicity. Therefore, to continuously explore and improve this method will significantly enhance and expand the practicability and application prospects of the method in the quantitative and elaborate studies of active faults.     

松辽盆地地层吸收特性和地震波衰减规律研究

选取有代表性的岩石样本，实验室模拟地下岩层的实际物理状态，对P波的品质因素Q和波速进行了测试，结果表明，松辽盆地地下岩层的P波Q和波速皆随压力的增中呈线性增加，随温度的增加呈线性减小；且Q与波速符合幂律关系，粘弹介质地震波场正演模拟表明，导致地震波衰减的主要是第四系低速带的影响，通过对震测井资料估算，按目前的地震采集方式，即潜水面（低速带）以下激发，检波器地面接收，从激发到接收，地震波在第四系中高频成分将损失170Hz，在最理想情况下，爆炸震源激发的初始子波频宽为402Hz，经过第四系和下伏地层吸收，第四系以下的反射波频带宽度不会超过232Hz，这是松辽盆地受地层吸收限制的高频采集极限。     

COMPARISON OF METHODS FOR DISTINGUISHING DIFFERENT GRADES OF GEOMORPHOLOGIC SURFACES BASED ON SEDIMENT PARTICLE SIZE FEATURES: TAKING THE QINGYIJIANG RIVER BASIN AS AN EXAMPLE

When using river geomorphology to study tectonic deformation, it is often difficult to distinguish the same level geomorphology in areas with severe weathering. In this paper, we take the geomorphologic surfaces of the Qingyijiang river basin as an example and try to distinguish the geomorphic surfaces by the sediment features that make up them. In order to distinguish different geomorphic surfaces, the traditional particle-size analysis method, SOFM network method and system clustering analysis method are taken to classify 29 samples from different geomorphic surfaces. The classification results of the three methods are different to a certain extent. We analyzed and compared the classification results of the three methods in detail. The results show that the traditional particle size analysis method, SOFM network method and cluster analysis method all can distinguish the geomorphic surface of different genesis, besides, they also can distinguish low-level terraces(T₁, T₂)and high-level terraces(T₃, T₄)for different grades of river terraces. Furthermore, the results also show that SOFM network method and cluster analysis method can make a certain distinction for the low-level terraces(T₁, T₂), while the traditional particle size analysis method is difficult to distinguish them. In addition, we analyzed and compared the three methods from the classification results, the results presentation, the operation process, and the error transmission. The results suggest that the advantages and disadvantages of the three methods are obvious. From the perspective of the classification results, the three methods all can distinguish the river terraces and alluvial fans and can make certain discrimination for different levels of river terraces. From the presentation of the results, the result of SOFM network is simple and clear. From the operation process, the traditional particle-size analysis method is relatively cumbersome, and the SOFM network method and the cluster analysis method are relatively simple to operate. From the perspective of error transmission, the traditional particle-size analysis method calculates the partial particle size feature value of the sample, which has a certain loss for the particle size distribution information of the whole sample. The error of the clustering analysis method has cumulative features and the influence exists consistently. The classification results of the SOFM network are independent of each other, which effectively avoids the problem of such error transmission of clustering analysis method. Overall, the classification results of the SOFM network method are simple and clear, the operation is simple, and the error is small. It has stronger adaptability to identifying different levels of different geomorphic surfaces. The results of this study will provide a simple and effective means for distinguishing different levels of geomorphic surfaces.