The effect of sub-alpine landslides on headwater stream gradient and beaver habitat

During previous work in the San Juan Mountains of Colorado, we observed that headwater (first-order) streams draining landslides were often characterized by the presence of beaver (Castor canadensis) dams whereas other headwater tributaries typically lacked evidence of beaver. Here, we hypothesize that hummocky landslide topography attracts beaver. To test the hypothesis, we examined 10 landslides and 11 adjacent headwater streams in the area, noting location, vegetation, elevation, and evidence of beaver activity, and then compared the landslide and non-landslide headwater streams using the G-test to determine whether or not variables were independent of one another. We reject the null hypothesis that beaver dam presence is unrelated to landslide deposits (p = 0.003). We further hypothesize that this relationship results from differences in stream gradient and concavity between landslide streams and other streams. We found streams on landslides to have a greater portion of their gradients below what geologic and ecologic literature suggests is a reasonable upper threshold (12%) for beaver dam maintenance. Additionally, streams on landslides are more concave. We conclude that the relationship between beaver presence and landslides results from a higher proportion of reaches below the 12% threshold and increased concavity of headwater streams on landslides.     

新疆吉木萨尔县贾家湾村滑坡防治工程

吉木萨尔县贾家湾村滑坡长期威胁着当地人民生命财产的安全,对其进行有效防治,已迫在眉睫。根据该滑坡灾害防治工程勘察、设计、施工全过程的资料成果,对其进行了进一步整理,在此基础上对滑坡产生的原因、稳定性、主要影响因素做系统分析,提出合理、可行的桩板墙防治工程措施。并对治理工程施工注意的问题和治理效果做了分析评价,为新疆后期的类似土质滑坡防治工程提供一些借鉴。     

多源遥感数据协同滑坡应急监测应用研究

在分析总结多源遥感数据在滑坡应急监测方面的应用研究现状与趋势的基础上,提出了一个基于高分辨率光学卫星遥感数据、卫星雷达数据和无人机遥感数据的多源遥感数据协同滑坡应急监测方法,构建了数据获取、快速处理和应急监测信息提取的技术流程;并通过恩施屯堡乡滑坡应急监测的实际案例,验证了多源遥感数据协同作业在滑坡应急监测中的应用,具...     

Landslides triggered by the 1949 Khait earthquake, Tajikistan, and associated loss of life

Earthquake-triggered landslides are a major geological hazard in Central Asia. In July 1949, the M7.4 Khait earthquake triggered many hundreds of landslides in a mountainous region near the southern limit of the Tien Shan Mountains, central Tajikistan. These landslides involved widespread rock-slope failure as well as large numbers of flowslides in loess that mantles the steep slopes of the region. In the Yasman valley hundreds of loess landslides coalesced to form a massive loess flow (est. vol. 245 Mm³) that travelled up to 20 km on a slope of only 2°. In an adjacent valley, the Khait landslide involved transformation of an earthquake-triggered rockslide into a very rapid flow by the entrainment of saturated loess into its movement. It travelled 7.41 km over a vertical distance of 1421 m with an estimated average velocity of ~30 m/s. We estimate its volume as 75 Mm³, an order of magnitude less that previously published estimates. The Khait landslide was simulated using DAN. The number of casualties due to earthquake-triggered landslides in the epicentral region was considerable. Approximately 4000 people were killed in the Yasman valley loess flow as 20 villages (kishlaks) were overwhelmed. In the Khait landslide alone we estimate ca. 800 people lost their lives when the villages of Khait and Khisorak were overrun by rapidly moving debris. Our data indicates that a total of approximately 7200 people were killed by earthquake-triggered landslides in the epicentral region of the Khait earthquake and that, in terms of loss of life, the 1949 Yasman valley loess flow was one of the most destructive landslides in recent history.     

Complexity Theory of Natural Disasters; Boundaries of Self-Structured Domains

Disasters are often represented as complete breakdowns of quasi-stationary states in a landscape, but may also be part of the normal evolution of such states. A landscape is, in fact, an open, nonlinear, dynamic system where the tectonic uplift and the seismic activity represent the input, the mass wastage and the relief degradation the output. The apparent 'stability' is due to the fact that open, nonlinear dynamic systems tend to develop into relatively stable, self-organized ordered states 'at the edge of chaos', with a fractal attractor. Short of complete breakdown, such systems re-establish order in steps of various magnitudes which have a power-law distribution. Because of the fractal structure of the basic attractor, all subsets follow a power law which accounts for the distribution of the steps of recovery. As the domains of quasi-stationarity at the edge of chaos are represented by finite windows, the power-law does not cover all magnitudes. The stationarity windows are not only limited in range, but also in space and time. This should be taken into account in the assessment of hazards. Examples are given from seismology (earthquake frequency), volcanology (eruption frequency), river hydrology (flood frequency) and geomorphology (landslides).     

指数平滑法及其在滑坡预报中的应用

指数平滑法是一种非统计性的预报方法，它具有计算过程简单，适应性好等优点，本文介绍的是其中的二次曲线指数平滑法及其在骨坡中，短期预报中的应用。     

Implications of palæo- and neotectonics in gully erosion-prone areas of southeastern Nigeria

Incidences of landsliding and gullying are prevalent in parts of southeastern Nigeria. It is proposed here that the apparent susceptibility of the geologic formations to landsliding and gullying may indeed derive substantially from the effects of palæo- and neotectonic features. Tertiary palæotectonics created regional cuestas, joints and faults that now determine the pace of gully erosion. Recent tectonics and seismic effects cause ground vibrations that initiate movement on the marginally stable slopes. It is observed that southeastern Nigeria has climatic and land-use characteristics which are very similar to those of southwestern Nigeria, as well as being underlain by similar Tertiary formations, yet gully erosion and landslides are much less common in the latter. This is ascribed to the differences in the palæotectonic setting. Recent case incidences of tectonics-related disasters are presented.     

ANALYSIS OF METEOROLOGICAL CONDITION AND RESEARCH ON FORECAST OF LANDSLIDES AND DEBRIS FLOWS IN ZHEJIANG PROVINCE

1 INTRODUCTIONMeteorological factors, especially precipitation,have close links with geological calamities. Accordingto the statistics, more than 70% of the geologicalcalamities in China occur in rainy seasons. Manyresearchers are thus motivated to study …     

ANALYSIS OF METEOROLOGICAL CONDITION AND RESEARCH ON FORECAST OF LANDSLIDES AND DEBRIS FLOWS IN ZHEJIANG PROVINCE

1 INTRODUCTION Meteorological factors, especially precipitation,have close links with geological calamities. According to the statistics, more than 70% of the geological calamities in China occur in rainy seasons. Many researchers are thus motivated to study extensively to determine their relationship in the prediction of geological calamities [1-11].     

西安市白鹿塬滑坡发生时间预测研究

笔者通过对白鹿塬区降水与滑坡发生时间之间的规律进行总结，认为本区滑坡发生与降水的丰年有着密切的关系，并应用卡尔曼滤波分析法对白鹿塬区滑坡发生时间进行了全区性预测，提出白鹿塬滑坡发生具有10年左右的中周期，20年左右的长周期，应及早作好防治工作。