50
4 An Innovative Measurement Instrument …
was kept after each rainfall to ensure the approximate value of initial water content.
The topography meter was used to monitor the mass movement of the failure surface
under rainfall simulation.
4.3 Data Processing
4.3.1 Method to Calculate Gravity Erosion and Hydraulic
Erosion
Based on the contour map obtained from the topography meter, a 3D stereogram was
established with ArcGIS, and then the slope parameters such as volume, projection
area and point coordinates were obtained. The soil loss was calculated using the
following equations:
g (i, j) = v 1(i, j) − v 2(i, j)
(4.1)
T j = V j1 − V j2
(4.2)
H j = T j −
N
i=1
g (i, j)
(4.3)
where i represents the sequence number of the failure incident during a rainfall; j
represents the sequence number of the rainfall for a certain initial landform; g (i,j) is
the volume of an individual failure mass; v 1(i,j) and v 2(i,j) are the slope volumes in the
scope of the incident in the moments before and after the failure, respectively; T j is
the total amount of soil loss during a rainfall event; V j1 and V j2 are the slope volumes
in the moments before and after the rainfall, respectively; H j is the total amount of
soil loss caused by water flowing during the rainfall event; and N is the number of
failure events during a rainfall.
4.3.2 Method to Measure Slope Volume
The slope volume is measured with the following technical route as shown in Fig. 4.4.
Involved software includes the Chinese versions of QQ Video 2013 v4, Photoshop
6.0, R2V 5.5 and ArcGIS 10.0.
1. Getting screenshots in QQ Video and marking landslide traces in Photoshop
Case No. 1: Dealing with an individual collapse. Use the software QQ Video to
open the test video, and tap the keyboard shortcuts Alt+A to get the screenshots
4 An Innovative Measurement Instrument …
was kept after each rainfall to ensure the approximate value of initial water content.
The topography meter was used to monitor the mass movement of the failure surface
under rainfall simulation.
4.3 Data Processing
4.3.1 Method to Calculate Gravity Erosion and Hydraulic
Erosion
Based on the contour map obtained from the topography meter, a 3D stereogram was
established with ArcGIS, and then the slope parameters such as volume, projection
area and point coordinates were obtained. The soil loss was calculated using the
following equations:
g (i, j) = v 1(i, j) − v 2(i, j)
(4.1)
T j = V j1 − V j2
(4.2)
H j = T j −
N
i=1
g (i, j)
(4.3)
where i represents the sequence number of the failure incident during a rainfall; j
represents the sequence number of the rainfall for a certain initial landform; g (i,j) is
the volume of an individual failure mass; v 1(i,j) and v 2(i,j) are the slope volumes in the
scope of the incident in the moments before and after the failure, respectively; T j is
the total amount of soil loss during a rainfall event; V j1 and V j2 are the slope volumes
in the moments before and after the rainfall, respectively; H j is the total amount of
soil loss caused by water flowing during the rainfall event; and N is the number of
failure events during a rainfall.
4.3.2 Method to Measure Slope Volume
The slope volume is measured with the following technical route as shown in Fig. 4.4.
Involved software includes the Chinese versions of QQ Video 2013 v4, Photoshop
6.0, R2V 5.5 and ArcGIS 10.0.
1. Getting screenshots in QQ Video and marking landslide traces in Photoshop
Case No. 1: Dealing with an individual collapse. Use the software QQ Video to
open the test video, and tap the keyboard shortcuts Alt+A to get the screenshots