142
9 Gravity Erosions on the Loess Gully Bank …
5
4
3
4000
3 0 0 0
1
2(i)
2(ii)
6
Fig. 9.1 Study area and experimental arrangement. Keys: 1. Rainfall simulator; 2. Topography
meter (i: Camera with a collimator, ii: Laser source); 3. Positioning marks; 4. Model slope;
5. Equidistant horizontal projections; 6. Receiving pool
breakdown and transportation of weathered materials. The phenomena can be classified in part by the spatial size and distribution on the ground, or by the duration of
time that the process acts, or by the rate of movement (Wang et al. 2014; Shroder and
Bishop 1998). It may also differ with respect to the thickness of a failed mass, time of
failure occurrence, or rotational inclination (Au 1998). Forms of gravitational erosion
include avalanche, landslide, mudflow, and sinkhole formation. Climate and landform play significant roles in the occurrence and behavior of gravity erosion. Gravity
erosion generally takes place together with hydraulic erosion, namely, soil loss due
to water flowing over the slope, but the mechanism and dynamics of each type of
erosion are different. Hence the measures to control hydraulic erosion and gravity
erosion are different, and it is essential to quantitatively distinguish the amounts of
the failure masses during the same event of rainfall (Xu et al. 2015).
Most gravity erosion occurs during or just after storms (Ali et al. 2014; Peruccacci
et al. 2012; Tsai and Yang 2006; Salciarini et al. 2006; Fourie 1996; Montgomery
and Dietrich 1994). Slope stability problems due to rainfall are often encountered
in geotechnical engineering, either in tropic regions with frequent rainfall or in arid
regions (Tu et al. 2009; Tsaparas et al. 2002; Derbyshire et al. 1995). Even though
an otherwise stable slope may fail due to human-induced factors, such as excavation
at the toe or loading due to construction, many slopes simply fail due to rainfall infiltration (Ali et al. 2014; Fourie 1996). In the area of Three Gorge Reservoir of China,
the frequency of rain-induced landslides accounted for 75% of the total geological
disasters since building the reservoir (Li et al. 2011). Hence, the determination of
geological mechanisms for the occurrence of the rain-induced gravity erosion is a
problem of scientific and societal interest.
9 Gravity Erosions on the Loess Gully Bank …
5
4
3
4000
3 0 0 0
1
2(i)
2(ii)
6
Fig. 9.1 Study area and experimental arrangement. Keys: 1. Rainfall simulator; 2. Topography
meter (i: Camera with a collimator, ii: Laser source); 3. Positioning marks; 4. Model slope;
5. Equidistant horizontal projections; 6. Receiving pool
breakdown and transportation of weathered materials. The phenomena can be classified in part by the spatial size and distribution on the ground, or by the duration of
time that the process acts, or by the rate of movement (Wang et al. 2014; Shroder and
Bishop 1998). It may also differ with respect to the thickness of a failed mass, time of
failure occurrence, or rotational inclination (Au 1998). Forms of gravitational erosion
include avalanche, landslide, mudflow, and sinkhole formation. Climate and landform play significant roles in the occurrence and behavior of gravity erosion. Gravity
erosion generally takes place together with hydraulic erosion, namely, soil loss due
to water flowing over the slope, but the mechanism and dynamics of each type of
erosion are different. Hence the measures to control hydraulic erosion and gravity
erosion are different, and it is essential to quantitatively distinguish the amounts of
the failure masses during the same event of rainfall (Xu et al. 2015).
Most gravity erosion occurs during or just after storms (Ali et al. 2014; Peruccacci
et al. 2012; Tsai and Yang 2006; Salciarini et al. 2006; Fourie 1996; Montgomery
and Dietrich 1994). Slope stability problems due to rainfall are often encountered
in geotechnical engineering, either in tropic regions with frequent rainfall or in arid
regions (Tu et al. 2009; Tsaparas et al. 2002; Derbyshire et al. 1995). Even though
an otherwise stable slope may fail due to human-induced factors, such as excavation
at the toe or loading due to construction, many slopes simply fail due to rainfall infiltration (Ali et al. 2014; Fourie 1996). In the area of Three Gorge Reservoir of China,
the frequency of rain-induced landslides accounted for 75% of the total geological
disasters since building the reservoir (Li et al. 2011). Hence, the determination of
geological mechanisms for the occurrence of the rain-induced gravity erosion is a
problem of scientific and societal interest.