Hazard And Risk Evaluation Of Fatal Landslides In China And The Landslides On The Loess Plateau

The landslides are one of the most frequent geo-hazards in China,and fatal landslides have caused serious fatalities and significant socio-economic losses.The Loess Plateau is the most prevalent area of landslides occurrence,and various types of loess landslides also resulted in huge losses in human lives and properties.Such events have brought serious impacts to socio-economic development and urbanization construction throughout the country.To fully recognize the consequence and threat taken by fatal landslides and further guide landslides prevention and mitigation,this paper collected the data of fatal events and a statistical analysis was carried out on person's and economic losses,trend changes and spatial distribution of different levels of these events,and then the semi-quantitative estimation method was used to assess the landslides hazard and risk.The results show that 527 landslide events caused 5151 deaths and 6.7 billion yuan loss in economic term.Also,more fatal landslides have been recorded with hazard records improvement.The fatal landslides show intensive clusters in southwestern and southern China,due to the possible distinctive geological environment and precipitation conditions.The temporal distribution reveals significant association with the rainy season.The results also show that the landslides density values in Sichuan,Guizhou,Hunan,Guangdong,Guangxi and Fujian are higher,which also indicate that these provinces are suffering greater landslide hazard,while Gansu has the highest fatality densities.The fatal landslides risk evaluation used semi-quantitative estimation reveals that the number of landslides mitigation projects,the increasing percentages of construction land and the area of protective forest are quite different for landslide risk.The results also show that many provinces are facing different degrees of landslide risk,but most of them have relatively low landslide risk.The inter-annual variations of fatal landslides on the Loess Plateau are quite different.However,there is a downward trend in recent years.The spatial distribution of the fatal landslides in the Loess Plateau is also obviously different.Gansu has the largest number,followed by Shaanxi and Shanxi.The results of landslide risk based on geometric parameters of loess landslides show that the frequency-volume relationships of different types show a consistent rule.The sliding and fall types have exponential inversion in a small volume region,but the large and medium-size landslides exhibit a power-law decay at the tail,and the fitted exponents are concentrated.Besides,the increase of loess landslides volume corresponds to decrease of the H/L ratio.The sliding type in loess-bedrock interface shows a dense distribution around large volume and H/L ratio decreases sharply with the volume increasing.Such trend reveals the maximum length of this landslide type is longer and thus it moves farther and brings a greater threat to human beings.On the other side,the relationship between the area and volume of loess landslides shows that area increment of loess landslide in China is larger with the increase of volume,and thus cause greater landslide risk after occurring.The consequences on landslide hazard and risk evaluation in the whole nation and in the Loess Plateau are severe.However,the Chinese government has devoted a lot of human and financial resources to landslides mitigation in the past few years.And under the construction of the village-based early warning system,the public awareness of the landslides hazard has improved and thus they can be saved from the hazards.At the same time,such study could also provide the guidance and reference for landslide hazard assessment and evaluation in other countries or regions at a global scale.