Abstract
This research investigates geohazards and preventative countermeasures for Lanzhou City, China. To investigate the factors related to the development of geohazards in Lanzhou, the regional geological conditions around Lanzhou were investigated. The geomorphology of the region is comprised of a loess landform underlying quaternary loess deposits. A large number of faults induced by strong neotectonic movements are present in the area. Therefore, earthquakes frequently occur around Lanzhou. Earthquakes cause numerous rock falls and landslides, with landslide masses found scattered on the upper middle level of the area’s mountains. When intense rainfall occurs, a lot of loose deposits are brought together along steep gullies, forming debris flows; hence, a disaster chain of earthquake–landslide–debris flow is formed. To evaluate the georisks around Lanzhou, the Analytic Hierarchy Process (AHP) was employed to assess geohazards. The spatial distribution of the evaluated georisk levels was mapped using a Geographic Information System (GIS). Based on the assessed results, about 55% of the urban area and 44% of Gaolan County have high or very high-risk levels. The ratio of relatively high disaster risk levels is up to 31% of the total area. To mitigate these geohazards, both strategic decision making and technical countermeasures should be implemented.
Highlights
In recent years, many cities in China have been subjected to extreme weather hazards due to climatic changes [1,2,3,4,5]
Assessment of disaster risk using Analytic Hierarchy Process (AHP) incorporated into geographic information system (GIS) is helpful in the assessment of geohazard risk [56,57,58,59]
The geohazards investigation shows that intensive seasonal short-duration rainstorm and special loess landforms with many vertical fissures contribute to frequent landslides, which are often accompanied by debris flows
Summary
Many cities in China have been subjected to extreme weather hazards due to climatic changes [1,2,3,4,5]. Recent extreme weather events have included flooding hazards in Guangzhou. Large-scale geohazards in the northwestern region of China may occur due to its special geographical location and semi-arid climatic conditions. In the northwestern region of China, geohazards (for example, earthquake–landslide–debris flow and flooding) frequently occur [6,7,8,9,10,11,12]. In the northwestern parts of the region, three mountain ranges (the Altay, Tianshan, and Kunlun Mountains) can be found
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