Variability in rainfall threshold for debris flow after the Chi-Chi earthquake in central Taiwan, China

The purpose of this study is to analyze variability in rainfall threshold for debris flow （critical rainfall for debris flow triggering） after the ML 7.3 Chi-Chi earthquake in central Taiwan in 1999. Two study sites with different geological conditions were surveyed in the earthquake area. Streambed surveys were conducted to continuously monitor debris flows between 1999 and 2006. During the 7-year study period, every debris flow event was identified, and the streambed characterized. Results show that the rainfall threshold for debris flow was remarkably lower just after the Chi-Chi Earthquake, but gradually recovered. To date, this rainfall threshold is still lower than the original level prior to the earthquake. This variability in rainfall threshold is closely related to the mount of sediment material in the initiation area of debris flow, which increased rapidly due to landslides resulting from the earthquake. With the increase in sediment material, the rainfall threshold was lowered severely during the first year following the Chi-Chi earthquake. However, heavy rainfalls mobilized the sediment material, causing debris flows and transporting sediment downstream. With the decrease in sediment material, the rainfall threshold recovered gradually over time. Furthermore, debris flows occurred only in the subbasins that had sufficient sediment material to cause significant movement. Hence, these results confirm that the sediment material in the initiation area of debris flow is a crucial component of the rainfall threshold for debris flow.     

汶川8．0级地震HRT波地震短临波动前兆及HRT波地震短临预测方法——关于实现强震短临预测可能性的讨论

2004年初开始在川滇地区布设的4个地电台,使用所研制的抗干扰性能极强的PS-100地电测量系统和技术,捕捉地震短临前兆．至2008汶川8．0级地震前,唯一仍在工作的红格台记录到了汶川地震的HRT波短临前兆．根据潮汐力谐振共振波（简称为HRT波）短临地震预测模型,在汶川8．0级地震前5月11日夜至12日凌晨5时分析得到了大震即将来临的结果．所记前兆同以前各台对其他强震所记的HRT波震例的规律有很强的一致性．所测物理量（地电阻率与地电流）仅在强震前才出现潮汐力的周期,而其振幅在震前数月至几天明显增大．通过研究所记的实例表明,它们通常与几天后所发生的地震有因果关系,这种波的到时与台站的震中距成正比;由这种波动所测的断层固有周期％与断层长度（震级）有关,对6-9级地震,死的范围为1-6h．有证据表明,它们是来自即将发生地震的震源区．这种波动周期较长,在地壳中,可传播数百乃至数千公里．对发生在地壳中的浅源大震,地壳固体在其孔、裂隙中通常含有易于流动的（导电的）流体（溶液）,这种流体在地震孕育过程中因受力（孔隙压力）先于断层位移（地震）产生的（微小）扰动（波动）,对所观测的HRT波提供了一种可能的解释．从2004年在川滇地区增设4个PS-100HRT波台站,试图捕捉强震短临前兆,到2008年发生汶川8．0级地震（距离新增的MN台△=288km;距离记录到HRT波短临异常的HG台△=465km;距离青川640km）前,HG台捕捉到汶川8．0级地震的HRT短临前兆的全过程,表明地震是有前兆的,地震是可以预测、预报的,在可预见的将来实现地震的短临预报是可行的．     

CGMS集成统计工具STATCAT的应用

通过对CGMS集成统计工具软件STATCAT的应用介绍及统计预测检验,表明统计工具STATCAT具有较好的统计功能和预测效果,该统计工具对CGMS在黑龙江省业务化的应用发展具有重要作用。     

对吉林省市级以上气象台气温预报能力的检验分析

1引言 随着社会的发展进步,人们更加关注天气预报,而气温是重要的天气预报要素之一,气温预报的准确与否直接影响着人们的日常工作和生活。吉林省气象局根据社会的需求和气象的发展形势于2003年3月规定对全省九大市的气温预报结果进行评定,各地区上传电视天气预报,吉林省气象台预报员可根据天气形势以及预报经验对市气象台的预报结果进行订正,订正的结果作为省台预报员的最后结果来进行评分,这对平时只注重单站温度的预报员来说难度更大了,这就要求预报员不但要认真分析天气形势,还要对当地的地形、地貌以及对气温影响较大的因素加以深入地了解和分析,以便进行合理订正。     

行政区勘界地形图的数字化管理系统

介绍以地理信息技术为依托,建立勘界资料数据库的设计,方法和质量标准等方面的经验,试验数据库输出的勘界地图等资料符合勘界工作的要求。     

MATHEMATICAL MODELS FOR LIQUID-SOLID TWO-PHASE FLOW

I INTRODUCTIONTurbulence models for single-phase fluid flows have been developed and widely applied in mechanical,aeronautical, environmental and hydraulic engineering, and other fields. The closure techniques for theReynolds-averaged Navier-Stokes equations for various levels of models including the simple turbulencemodel, one-equation turbulence model, k-s turbulence model and turbulence stress/flux model have beenverified to be physically reasonable and have acceptable accuracy in app…     

海安台地电阻各向异性变化与地震

应用电阻率的各生方法研究了海安台地电阻率变化,发现海安台电阻率各向异性变化与其２５０ｍ范围内的Ｍ６．０以上地震有很好的对应,另外,对今后海安台附近的地震趋势作了预测。     

岫岩—海城5.6级地震防震减灾工作

文章通过作者亲身经历和感受,动用翔实的一手资料,从八个方面（长期准备、准备预报、科学决策、有效组织、救助组织、救助及时、社会稳定、地震灾情调查、地城损失评估）介绍了１９９９年１１月２９日,岫岩－海城５．６级地震前后的应急工作;分析这次地夺的成功预报与有效应急措施才能取得面对一次破坏性地震,要充分发挥政府职能作用,搞好地震综合防御工作势在必行。     

应用高压注浆技术解决基础沉降

本溪市长途通讯枢纽楼在施工２号人工挖孔桩时,与之相邻的万门程控楼西侧开始下沉,北侧墙体开裂严重。分析沉降原因是人工挖孔桩抽水携带粉细砂使万门程控楼砂层地基孔隙增大所致。经对万门程控楼进行注浆加固,对护坡钢桩上部的悬墙和２号桩附近的钢桩进行锚杆加固及对２号桩桩孔周围进行帷幕注浆和基底加固注浆,阻止了万门程控楼继续下沉,并使基得取回升。     

重庆市丰都县弹子台水库工程地质问题

根据室内外大量调查测试资料,对重庆市丰都县弹子台水库特殊的工程地质问题,进行了阐述和深入系统分析,所得结论为该水库的论证和设计提供了依据。