Bivariate statistical analysis of data-driven approaches is widely used for landslide susceptibility assessment, and the frequency ratio(FR) method is one of the most popular. However, the results of such assessments ...Bivariate statistical analysis of data-driven approaches is widely used for landslide susceptibility assessment, and the frequency ratio(FR) method is one of the most popular. However, the results of such assessments are dominated by the number of classes and bounds of landslide-related causative factors, and the optimal assessment is unknown. This paper optimizes the frequency ratio method as an example of bivariate statistical analysis for landslide susceptibility mapping based on a case study of the Caiyuan Basin, a region with frequent landslides, which is located in the southeast coastal mountainous area of China. A landslide inventory map containing a total of 1425 landslides(polygons) was produced, in which 70% of the landslides were selected for training purposes, and the remaining were used for validationpurposes. All datasets were resampled to the same 5 m × 5 m/pixel resolution. The receiver operating characteristic(ROC) curves of the susceptibility maps were obtained based on different combinations of dominating parameters, and the maximum value of the areas under the ROC curves(AUCs) as well as the corresponding optimal parameter was identified with an automatic searching algorithm. The results showed that the landslide susceptibility maps obtained using optimal parameters displayed a significant increase in the prediction AUC compared with those values obtained using stochastic parameters. The results also showed that one parameter named bin width has a dominant influence on the optimum. In practice, this paper is expected to benefit the assessment of landslide susceptibility by providing an easy-to-use tool. The proposed automatic approach provides a way to optimize the frequency ratio method or other bivariate statistical methods, which can furtherfacilitate comparisons and choices between different methods for landslide susceptibility assessment.展开更多
The "4.20" Lushan earthquake in Sichuan province, China has induced a large amount of geological hazards and produced abundant loose materials which are prone to post-earthquake rainfalltriggered landslides....The "4.20" Lushan earthquake in Sichuan province, China has induced a large amount of geological hazards and produced abundant loose materials which are prone to post-earthquake rainfalltriggered landslides. A detailed landslide inventory was acquired through post-earthquake emergent field investigation and high resolution remote sensing interpretation. The rainfall analysis was conducted using historical rainfall records during the period from 1951 to 2010. Results indicate that the average annual rainfall distribution is heterogeneous and the largest average annual rainfall occurs in Yucheng district. The Stability Index MAPping(SINMAP)model was adopted to assess and analyze the postearthquake slope stability under different rainfall scenarios(light rainfall, moderate rainfall, heavy rainfall, and rainstorm). The model parameters were calibrated to reflect the significant influence of strong earthquakes on geological settings. The slope stability maps triggered by different rainfall scenarios wereproduced at a regional scale. The effect of different rainfall conditions on the slope stability is discussed.The expanding trend of the unstable area was quantitatively assessed with the different critical rainfall intensity. They provide a new insight into the spatial distribution and characteristics of postearthquake rainfall-triggered landslides in the Lushan seismic area. An increase of rainfall intensity results in a significant increase of unstable area. The heterogeneous distribution of slope instability is strongly correlated with the distribution of earthquake intensity in spite of different rainfall conditions. The results suggest that the both seismic intensity and rainfall are two crucial factors for postearthquake slope stability. This study provides important references for landslide prevention and mitigation in the Lushan area after earthquake.展开更多
Landslide warning models are important for mitigating landslide risks.The rainfall threshold model is the most widely used early warning model for predicting rainfall-triggered landslides.Recently,the rainfall thresho...Landslide warning models are important for mitigating landslide risks.The rainfall threshold model is the most widely used early warning model for predicting rainfall-triggered landslides.Recently,the rainfall threshold model has been coupled with the landslide susceptibility(LS)model to improve the accuracy of early warnings in the spatial domain.Existing coupled models,designed based on a matrix including predefined rainfall thresholds and susceptibility levels,have been used to determine the warning level.These predefined classifications inevitably have subjective rainfall thresholds and susceptibility levels,thus affecting the probability distribution information and eventually influencing the reliability of the produced early warning.In this paper,we propose a novel landslide warning model in which the temporal and spatial probabilities of landslides are coupled without predefining the classified levels.The temporal probability of landslides is obtained from the probability distribution of rainfall intensities that triggered historical landslides.The spatial probability of landslides is then obtained from the susceptibility probability distribution.A case study shows that the proposed probability-coupled model can successfully provide hourly warning results before the occurrence of a landslide.Although all three models successfully predicted the landslide,the probability-coupled model produced a warning zone comprising the fewest grid cells.Quantitatively,the probabilitycoupled model produced only 39 grid cells in the warning zone,while the rainfall threshold model and the matrix-coupled model produced warning zones including 81 and 49 grid cells,respectively.The proposed model is also applicable to other regions affected by rainfall-induced landslides and is thus expected to be useful for practical landslide risk management.展开更多
目的观察穴位注射配合药物治疗带状疱疹后遗神经痛的临床疗效。方法将64例带状疱疹后遗神经痛患者随机分为治疗组和对照组,每组32例。治疗组采用夹脊穴注射丹参注射液配合口服加巴喷丁片治疗,对照组采用单纯口服加巴喷丁片治疗。两组如...目的观察穴位注射配合药物治疗带状疱疹后遗神经痛的临床疗效。方法将64例带状疱疹后遗神经痛患者随机分为治疗组和对照组,每组32例。治疗组采用夹脊穴注射丹参注射液配合口服加巴喷丁片治疗,对照组采用单纯口服加巴喷丁片治疗。两组如疼痛严重可加服盐酸曲马多缓释片治疗。观察两组治疗前后视觉模拟评分法(visual analogue scale, VAS)评分、SF-36健康量表(the MOS 36-item short-form health survey,SF-36)各项评分的变化情况,并比较两组不同时间点服用加巴喷丁片和盐酸曲马多缓释片的剂量及各项不良反应的发生率。结果两组治疗后不同时间点(治疗1周、3周、6周、12周、24周后)VAS评分与同组治疗前比较,差异均有统计学意义(P<0.01)。治疗组治疗后不同时间点VAS评分与对照组比较,差异具有统计学意义(P<0.01)。两组治疗3周、6周、12周、24周后加巴喷丁片和盐酸曲马多缓释片的服用剂量比较,差异均具有统计学意义(P<0.05)。两组治疗12周、24周后SF-36各项评分(PF、RP、BP、GH、VT、SF、RE、MH)与同组治疗前比较,差异均具有统计学意义(P<0.05)。治疗组治疗12周、24周后SF-36中PF、RP、BP、VT、MH评分与对照组比较,差异均具有统计学意义(P<0.05)。治疗组治疗后头晕、嗜睡、恶心的发生率分别为6.7%、3.3%和3.3%,对照组分别为24.1%、17.2%和20.7%,两组比较差异均具有统计学意义(P<0.05)。结论穴位注射配合药物是一种治疗带状疱疹后遗神经痛的有效方法,能减少服用加巴喷丁片的剂量,从而减少不良反应。展开更多
基金funded by the National Natural Science Foundation of China(Grant NO.41525010,41807291,41421001,41790443 and 41701458)the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(Grant NO.XDA23090301 and XDA19040304)+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(CAS)(Grant NO.QYZDY-SSW-DQC019)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0904)
文摘Bivariate statistical analysis of data-driven approaches is widely used for landslide susceptibility assessment, and the frequency ratio(FR) method is one of the most popular. However, the results of such assessments are dominated by the number of classes and bounds of landslide-related causative factors, and the optimal assessment is unknown. This paper optimizes the frequency ratio method as an example of bivariate statistical analysis for landslide susceptibility mapping based on a case study of the Caiyuan Basin, a region with frequent landslides, which is located in the southeast coastal mountainous area of China. A landslide inventory map containing a total of 1425 landslides(polygons) was produced, in which 70% of the landslides were selected for training purposes, and the remaining were used for validationpurposes. All datasets were resampled to the same 5 m × 5 m/pixel resolution. The receiver operating characteristic(ROC) curves of the susceptibility maps were obtained based on different combinations of dominating parameters, and the maximum value of the areas under the ROC curves(AUCs) as well as the corresponding optimal parameter was identified with an automatic searching algorithm. The results showed that the landslide susceptibility maps obtained using optimal parameters displayed a significant increase in the prediction AUC compared with those values obtained using stochastic parameters. The results also showed that one parameter named bin width has a dominant influence on the optimum. In practice, this paper is expected to benefit the assessment of landslide susceptibility by providing an easy-to-use tool. The proposed automatic approach provides a way to optimize the frequency ratio method or other bivariate statistical methods, which can furtherfacilitate comparisons and choices between different methods for landslide susceptibility assessment.
基金supported by the Project of the 12th Five-year National Sci-Tech Support Plan of China (2011BAK12B09)the National Science Foundation of China (41072241)+1 种基金the One Hundred Talents Program of Chinese Academy of Sciences (A1055)the China Geological Survey Project (12120113038000)
文摘The "4.20" Lushan earthquake in Sichuan province, China has induced a large amount of geological hazards and produced abundant loose materials which are prone to post-earthquake rainfalltriggered landslides. A detailed landslide inventory was acquired through post-earthquake emergent field investigation and high resolution remote sensing interpretation. The rainfall analysis was conducted using historical rainfall records during the period from 1951 to 2010. Results indicate that the average annual rainfall distribution is heterogeneous and the largest average annual rainfall occurs in Yucheng district. The Stability Index MAPping(SINMAP)model was adopted to assess and analyze the postearthquake slope stability under different rainfall scenarios(light rainfall, moderate rainfall, heavy rainfall, and rainstorm). The model parameters were calibrated to reflect the significant influence of strong earthquakes on geological settings. The slope stability maps triggered by different rainfall scenarios wereproduced at a regional scale. The effect of different rainfall conditions on the slope stability is discussed.The expanding trend of the unstable area was quantitatively assessed with the different critical rainfall intensity. They provide a new insight into the spatial distribution and characteristics of postearthquake rainfall-triggered landslides in the Lushan seismic area. An increase of rainfall intensity results in a significant increase of unstable area. The heterogeneous distribution of slope instability is strongly correlated with the distribution of earthquake intensity in spite of different rainfall conditions. The results suggest that the both seismic intensity and rainfall are two crucial factors for postearthquake slope stability. This study provides important references for landslide prevention and mitigation in the Lushan area after earthquake.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA23090301)the National Natural Science Foundation of China(Grant No.42041006 and 41927806)the Fundamental Research Funds for the Central Universities,CHD(Grant No.300102262901)。
文摘Landslide warning models are important for mitigating landslide risks.The rainfall threshold model is the most widely used early warning model for predicting rainfall-triggered landslides.Recently,the rainfall threshold model has been coupled with the landslide susceptibility(LS)model to improve the accuracy of early warnings in the spatial domain.Existing coupled models,designed based on a matrix including predefined rainfall thresholds and susceptibility levels,have been used to determine the warning level.These predefined classifications inevitably have subjective rainfall thresholds and susceptibility levels,thus affecting the probability distribution information and eventually influencing the reliability of the produced early warning.In this paper,we propose a novel landslide warning model in which the temporal and spatial probabilities of landslides are coupled without predefining the classified levels.The temporal probability of landslides is obtained from the probability distribution of rainfall intensities that triggered historical landslides.The spatial probability of landslides is then obtained from the susceptibility probability distribution.A case study shows that the proposed probability-coupled model can successfully provide hourly warning results before the occurrence of a landslide.Although all three models successfully predicted the landslide,the probability-coupled model produced a warning zone comprising the fewest grid cells.Quantitatively,the probabilitycoupled model produced only 39 grid cells in the warning zone,while the rainfall threshold model and the matrix-coupled model produced warning zones including 81 and 49 grid cells,respectively.The proposed model is also applicable to other regions affected by rainfall-induced landslides and is thus expected to be useful for practical landslide risk management.
文摘目的观察穴位注射配合药物治疗带状疱疹后遗神经痛的临床疗效。方法将64例带状疱疹后遗神经痛患者随机分为治疗组和对照组,每组32例。治疗组采用夹脊穴注射丹参注射液配合口服加巴喷丁片治疗,对照组采用单纯口服加巴喷丁片治疗。两组如疼痛严重可加服盐酸曲马多缓释片治疗。观察两组治疗前后视觉模拟评分法(visual analogue scale, VAS)评分、SF-36健康量表(the MOS 36-item short-form health survey,SF-36)各项评分的变化情况,并比较两组不同时间点服用加巴喷丁片和盐酸曲马多缓释片的剂量及各项不良反应的发生率。结果两组治疗后不同时间点(治疗1周、3周、6周、12周、24周后)VAS评分与同组治疗前比较,差异均有统计学意义(P<0.01)。治疗组治疗后不同时间点VAS评分与对照组比较,差异具有统计学意义(P<0.01)。两组治疗3周、6周、12周、24周后加巴喷丁片和盐酸曲马多缓释片的服用剂量比较,差异均具有统计学意义(P<0.05)。两组治疗12周、24周后SF-36各项评分(PF、RP、BP、GH、VT、SF、RE、MH)与同组治疗前比较,差异均具有统计学意义(P<0.05)。治疗组治疗12周、24周后SF-36中PF、RP、BP、VT、MH评分与对照组比较,差异均具有统计学意义(P<0.05)。治疗组治疗后头晕、嗜睡、恶心的发生率分别为6.7%、3.3%和3.3%,对照组分别为24.1%、17.2%和20.7%,两组比较差异均具有统计学意义(P<0.05)。结论穴位注射配合药物是一种治疗带状疱疹后遗神经痛的有效方法,能减少服用加巴喷丁片的剂量,从而减少不良反应。