Multi-temporal modeling of road-induced overland flow alterations in a terraced landscape characterized by shallow landslides

The presence of roads in high steep agricultural systems is often linked with landslides occurrence. This research aims to model multi-temporal overland flow dynamics in a shallow landslides-prone terraced landscape (northern Italy).The combined use of Remotely Piloted Aircraft Systems (RPAS) and photogrammetric techniques (e.g., Structure from Motion-SfM) allowed to elaborate multi-temporal high-resolution Digital Elevation Models (DEMs). Hydrological analyses of water flow's depth alterations due to the road presence were carried out adopting the SIMulated Water Erosion model (SIMWE), focusing on different scenarios considering the presence of the road and assuming its absence through a specific DEM smoothing procedure. The possibility to perform multi-temporal hydrological simulations at a hillslope scale so as to analyse the role played by the road in overland flows alteration is still a challenge to be investigated. Results proved the role played by the road in water flows change above the two observed shallow landslides, with respective maximum water depth values equal to 0.18 m and 0.14 m. On the contrary, no-road simulations not revealed significant water flows deviations towards landslides, with water depth values around 0 m, underlining that the absence of the road would avoid relevant changes in water flow paths toward the collapsed surfaces. This work could be a solid starting point for analyse road impact on runoff dynamics and hillslopes stability also at a wider scale, as well as for planning efficient mitigation intervention so as to reduce the occurrence of similar future scenarios.     

云南瑞丽市灾种统计的防治意义

统计了云南省瑞丽市灾害的类型及6个乡镇灾害的分布情况,同时分析了灾种发生的坡度、岩性组合以及诱发因素的种类。结果表明,云南瑞丽市地质灾害类型有滑坡、崩塌、泥石流和不稳定斜坡。滑坡多发生在第四系成因的含砾粉土中;崩塌多发生在泥岩、片麻岩构成且地质构造发育的陡坎、陡崖部位;降雨是地质灾害最主要的诱发因素,不合理的人类工程活动加剧了地质灾害发生频率;地震也是诱发地质灾害产生的原因之一。     

Plant litter decomposition influenced by soil animals and disturbance in a subtropical rainforest of Taiwan

Soil fauna has been postulated as one of the paramount determinants of decomposition in the humid tropics. However, its effect on litter decomposition has only been demonstrated in few forest sites in Central America. In addition, landslide is a common disturbance associated with heavy rainfall brought by tropical cyclones in the tropics and can potentially alter abundance and structure of soil animals and thus affect litter decomposition. In this study, we examined the effect of soil animals on litter decomposition in an Asian subtropical monsoon forest and compared the animal effects in landslide-disturbed (2 years old) and undisturbed sites. Animal exclusion by naphthalene treatment significantly reduced the density and diversity of litterbag animals and slowed down the rate of decomposition in both landslide-disturbed and undisturbed sites. However, density (per unit area) and diversity of the litter animals and litter decomposition rate did not differ between the landslide-disturbed and undisturbed sites for both control and animal-excluded treatments. Our data suggest that the abundance of soil animals is not limited by litter mass. Furthermore, soil fauna recover quickly from landslides, and fauna's facilitative effect on litter decomposition is not altered after their recovery.     

卢氏县地质灾害滑坡预报模型研究

根据卢氏县地质灾害易发程度等级区划,对滑坡个例进行了分类统计。结果表明,降水对不同滑坡危险等级区域的影响不同。根据前期不同量级降水诱发的滑坡发生概率,拟合出不同地质易发分区的前期降水对滑坡的贡献率指数方程和山体滑坡有效降水量方程,在此基础上建立了卢氏县不同地质灾害易发程度灾害区内山体滑坡预报指标模型。     

万宁一次暴雨型滑坡灾害分析

2009年10月22日受热带低压、低压槽和冷空气共同影响,海南岛出现强降水天气过程,东线高速公路发生多处滑坡地质灾害。通过对滑坡成因进行分析,得出了东线高速公路发生多处滑坡是在特定地形条件、大风和暴雨等气象因素共同作用下滑动失稳的滑坡。其中热带低压产生的强降水和大风力,是诱发东线高速公路暴雨型滑坡的直接原因。     

九畹溪滑坡的稳定性分析

本文通过对九畹溪滑坡的现场实际踏勘,确定了滑坡的地形地貌特征,滑坡体、滑带物质特征及滑床岩土体特征。在现场试验和室内试验的基础上,对滑坡在不同工况下的稳定性进行计算并得出结论,其计算结果对该地区滑坡治理提供了参考和依据。选取特征剖面,采用Morgenstern-Prince法分别计算了不同工况下斜坡的稳定性,计算斜坡的法向力和剪切力,分析该滑坡的稳定性情况。     

地形起伏度提取及其在区域滑坡灾害评价中的应用——以四川省为例

四川省位于我国西南部,省内地形地貌复杂多样,地势高差大,汶川—茂江、北川—映秀等几条大的断裂带广泛分布,地壳构造不稳定,地质灾害频繁发生,其中尤以滑坡灾害较为典型。滑坡灾害的发生与地形有着密切关系。探讨了四川省地形起伏度最佳统计单元的求证过程,经试验得出,2.25 km2为适宜四川省滑坡发育的地形起伏度计算的最佳单元。基于ArcGIS平台,结合区域滑坡灾害调查资料,初步研究了地形起伏度与滑坡灾害的相关性,并用信息量模型进行验证,在该基础上探讨了地形起伏度与区域滑坡灾害发生的规律,对区域防灾减灾具有重要的指导意义。     

某坝区滑坡变形破坏特征及其稳定性预判

雅砻江中游某巨型滑坡距离拟选坝址仅1.3 km,目前滑坡体上有裂缝发育,滑坡的整体稳定性对于坝址的选择具有颠覆性的影响。因此,在概要介绍滑坡地质特征基础上,对滑坡体上裂缝发育分布特征及其成因机理探讨,对裂缝的产生是由整体还是由于局部导致给出明确回答,进而依据滑坡工程地质特征及定量计算对蓄水后滑坡的整体稳定性作出预测。     

中国小兴安岭北部浅层滑坡地质与变形特征的研究

[目的]研究中国小兴安岭北部浅层滑坡的地质特征和变形特征.[方法]以穿越小兴安岭西北段的北安至黑河高速公路K178+ 530路段滑坡为例,采用地质勘察、地表GPS变形监测、路基和边坡土体地温变化监测等方法,研究分析滑坡的地质特征和变形特征.[结果]滑坡位于高纬度多年冻土区,区域内有岛状多年冻土层分布,由于大气降水、岛状多年冻土退化、区域气候条件和特殊的地质条件影响,滑坡每年5月末至11月初滑动,冬季处于稳定状态.至2014年1月,滑坡体中、后部滑动距离最大达113.32 m,滑坡体前缘向前滑动26.4m.[结论]滑坡体中、后部滑动速率大于前缘,滑坡滑动方式为推进式,滑坡的变形具有季节性、间歇性和低角度等特点.     

不同植被恢复方式对九寨沟震后土壤碳氮化学计量特征的影响

通过比较自然恢复、人为恢复及与自然植被的土壤碳氮化学计量特征,以期为九寨沟地震受损滑坡体快速恢复提供理论依据。结果表明:(1)与未受损植被的土壤相比,受损植被滑坡体的土壤有机碳、总氮、可利用氮含量均更低,但pH值和碳氮比均更高。(2)人为恢复下的植被总盖度、土壤有机碳、总氮、可利用氮含量均高于自然恢复。(3)土壤有机碳含量与总氮或可利用氮含量呈现正相关、而与pH值或碳氮比呈显著负相关。短期的结果表明人为恢复措施比自然恢复更有利于九寨沟震损坡体植被的快速恢复。此外,建议在未来植被恢复中注意栽植固氮植物。