长江上游滑坡、泥石流防灾减灾的探索与实践

长江上游是我国滑坡、泥石流灾害分布最为集中、危害最为严重的地区之一 ,约有大小滑坡 15万处、泥石流沟万余条。 1991年长江上游滑坡、泥石流预警系统建成并投入运行 ,10年多来坚持预防为主、分区分级管理、重点监测、专业监测与群测群防相结合 ,已成功预报 10 0多起滑坡、泥石流灾害险情 ,使 3 3万多人免遭灾难 ,避免直接经济损失达亿元 ,成效十分显著。介绍了长江上游滑坡、泥石流灾害及其特点、预警系统防灾减灾的主要经验等     

Landslide erosion risk to New Zealand pastoral steeplands productivity

Pastoral land use in New Zealand's North Island hill terrain has led to high rates of rainstorm-induced landslide erosion higher than existed under the indigenous forest regime, with consequent soil productivity declines in the long term. To assist extrapolation of research results to other areas, and to shed light on long-term erosion risks, a simple model was developed that simulates the evolution of hillslope soil productivity, taking into account the effect of slope, rainstorm magnitude–frequency relations and soil recovery rates. Risks are evaluated by Monte Carlo simulation, and reflect parameter uncertainty as well as the natural randomness associated with climatic events. A sensitivity analysis showed that landslide risk was most affected by the rainfall threshold for landsliding, the mean of the extreme value distribution for annual maximum storm rainfall, and the maximum degree of recovery of pasture productivity following landsliding. Simulations suggest productivity stabilizes at a reduced level well before all steep terrain is affected by landsliding, and that subsequent expected landslide-induced productivity declines are too slow to provide sufficient economic motivation for measures to prevent landslide damage. A refined model showed that long-term average rates of productivity decline are sensitive to changes in recovery rates resulting from progressive removal of the soil resource. Charts summarizing simulation results can be used to estimate long-term productivity declines. Copyright © 1999 John Wiley & Sons, Ltd.     

改进最小势能滑坡稳定性评价方法在田家寨滑坡中的应用

利用最小势能原理计算稳定系数的基本原理,根据其计算安全系数的局限性,结合瑞典条分法,综合考虑包括自重、地震力、水压力等方面的影响,计算出稳定系数,从而评价滑坡的稳定性,扩大了最小势能原理方法的工程应用范围,对实际的工程应用较前人的模型有了较大的进展,并利用田家寨滑坡对模型进行实例验证,证明了该方法的可行性和有效性。     

基于Mein-Larson入渗模型的降雨滑坡失稳破坏概率研究

[目的]评价降雨诱发浅层滑坡的失稳破坏概率,为相关研究提供理论依据。[方法]在引入并扩展了Mein-Larson降雨入渗模型的基础上,将Mein-Larson入渗模型与无限边坡稳定性方法有机结合,建立2种降雨情形(高强度短历时和低强度长历时)下降雨滑坡稳定性的确定性评价模型,然后再将蒙特卡洛数值模拟方法与降雨滑坡的确定性评价模型结合,建立降雨滑坡稳定性的概率评价方法。[结果]提出了1种降雨诱发浅层滑坡失稳的概率评价方法。[结论]概率评价方法可以描述降雨滑坡发生及发展过程中存在的不确定性,可以计算不同降雨情形下,不同降雨时刻降雨诱发边坡的失稳破坏概率。该方法的评价结果更符合边坡实际情况。     

Application of improved FAHP in schemes optimization about landslide treatment

Based on the landslide control scheme optimized by considering technical index and other factors,a landslide comprehensive control thought of “treating scheme optimization combined monitoring information feedback” is put forward.The multi level hierarchical comprehensive evaluation index on landslide control scheme is set up on the basis of analyzing many engineering examples,and formula of weight,fuzzy complementary judgment matrix and the consistency check method of judgment matrix of fuzzy analytical hierarchy process are given,the solution of multi objective decision problems based on improved fuzzy analytical hierarchy process is developed,too.Validity and reliability of this method is proved through the scheme selection for Xiangjiapo landslide control.It provides an effective method for construction decision makers.     

陕北菜园子老黄土滑坡开发利用的稳定性分析

采用FLAC/SLOP软件对陕北地区菜园子滑坡的稳定性进行了分析,并设计了该地区因地制宜开发利用滑坡地形的方案,为陕北黄土滑坡的合理开发利用提供了参考。     

Contribution of Topographically Based Landslide Hazard Modelling to the Analysis of the Spatial Distribution and Ecology of Kauri (Agathis australis)

In this paper the use of topographical attributes for the analysis of the spatial distribution and ecological cycle of kauri (Agathis australis), a canopy emergent conifer tree from northern New Zealand, is studied. Several primary and secondary topographical attributes are derived from a Digital Elevation Model (DEM) for a study area in the Waitakere Ranges. The contribution of these variables in explaining presence or absence of mature kauri is assessed with logistic regression and Receiver Operating Characteristic (ROC) plots. A topographically based landslide hazard index, calculated by combining a steady state hydrologic model with the infinite slope stability equation, appears to be very useful in explaining the occurrence and ecological dynamics of kauri. It is shown that the combination of topographical, soil physical and hydrological parameters in the calculation of this single landslide hazard index, performs better in explaining presence of mature kauri than using topographical attributes calculated from the DEM alone. Moreover, this study demonstrates the possibilities of using terrain attributes for representing geomorphological processes and disturbance mechanisms, often indispensable in explaining a species’ ecological cycle. The results of this analysis support the ‘temporal stand replacement model’, involving disturbance as a dominant ecological process in forest regeneration, as an interpretation of the community dynamics of kauri. Furthermore a threshold maturity stage, in which trees become able to stabilize landslide prone sites and postpone a possible disturbance, together with great longevity are seen as major factors making kauri a ‘landscape engineer’.     

长江上游滑坡泥石流预警系统中陇南陕南片防灾减灾效益评价

长江上游水土保持重点防治区陇南,陕南片滑坡,泥石流区分布广泛,危害严重,是中国４大滑坡,不得不充集中暴发区之一。长江上游水土保持重点防治区滑坡,泥石流预警系统陇南一级站自１９９１年起,开展了专业监测预警与群测群防相结合,走出了一条以预警站点为依托,以群测群防为基础,防治山地灾害的减灾避灾的新路子。     

基于土壤侵蚀模型的浅层滑坡预警研究

[目的]利用土壤侵蚀模型进行浅层滑坡的预警研究,为山区滑坡预警预报工作提供参考。[方法]选取陕西省紫阳县境内440km~2区域作为典型研究区,在已有历史滑坡资料、气象资料和卫星资料的基础上,基于土壤侵蚀模型(USLE),并结合地理信息系统(GIS),确定滑坡临界土壤侵蚀强度,再根据降雨侵蚀力与降雨量之间的关系,推求滑坡点的预警降雨量。[结果]土壤侵蚀强度与滑坡的发生存在较好的相关性,研究区域滑坡预警的临界土壤侵蚀强度按等级分别为69.6,136.7,179.4t/km~2。[结论]相比以往仅仅统计滑坡与降雨之间关系的传统方法,基于土壤侵蚀模型的方法考虑更全面,也易于实现。     

Improved Information Value Model and Its Application in the Spatial Prediction of Landslides

Information Value Model is used frequently in domestic landslide hazard zonation prediction, which plays a very important role for land-use planning especially in mountain area. Through theoretical analysis, the prerequisite of Information Value Model which should be used with influence-factors independent from each other is studied. Factor Analysis is adopted to evaluate and eliminate the influence of correlation between influence-factors in spatial prediction of landslides which are showed through case study. Relationships between landslides and influence-factors are studied based on a certain watershed in which the Information Value Model and Factor Analysis are applied. The probability of landslides changes regularly with the influence-factors, and based on which a method for the discretization of influence-factors is advised. The distribution of landslide susceptibility of above watershed is calculated and validated based on the area-ratio index with landslides occurring in nearly 5 years, which proves the credibility of Information Value Model.