Rapid loess flow slides in Heifangtai Terrace, Gansu, China

• Published in: Quarterly journal of engineering geology and hydrogeology 2017-05, Vol.50 (2), p.106-110
• Main Authors: Peng Jianbing, Peng Jianbing, Zhang Fanyu, Zhang Fanyu, Wang, Gonghui
• Format: Article
• Language: English
• Subjects: Agricultural land; Asia; China; clastic sediments; Clay; degradation; Ecological effects; Engineering geology; Environmental geology; Erosion; erosion features; Erosion rates; Failures; Far East; Fluvial deposits; Gansu China; geologic hazards; Groundwater; Groundwater levels; gullies; Heifangtai Terrace; Huang He; Irrigation; Land degradation; Land use; Landslides; Lanzhou China; Loess; Luijiaxia Dam; mass movements; natural hazards; Relocation; Rivers; sediments; slope stability; Soil; Soil erosion; soil mechanics; Soil permeability; soils; Terraces
• ISSN: 1470-9236; 2041-4803
• DOI: 10.1144/qjegh2016-065

The Heifangtai is located on the fourth terrace of the Yellow River, c. 60 km to the west of Lanzhou City, Gansu Province, China (Fig. 1a). The terrace has an area of 13.7 km2 and, since the 1960s, has been used as farmland by the people relocated from areas affected by the construction of the Liujiaxia Dam and its associated reservoir on the Yellow River. Large-scale irrigation on the terrace resulting from agricultural land use since the relocation has elevated groundwater levels by c. 20 m as a result of the presence of a relatively impermeable clay layer underlying more permeable loess deposits (Derbyshire et al. 2000; Dijkstra 2000; Zhang et al. 2013; Peng et al. 2016). This in turn has led to the occurrence of about 50 major landslides within the loess deposits of the terrace (Fig. 1b), with the total number of failures exceeding 110 (Peng et al. 2016). These loess landslides have caused more than 40 fatalities and have injured over 100 people. They have also resulted in serious ecological and environmental problems owing to the increased rates of soil erosion, land degradation and ground subsidence associated with them (Zhang et al. 2014).