Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment

China

Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment

China
SEARCH FILTERS
Time filter
Source Type

Chen Z.,China Agricultural University | Lei T.,China Agricultural University | Hu H.,Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment | Yan Q.,China Agricultural University | And 2 more authors.
American Society of Agricultural and Biological Engineers Annual International Meeting 2012, ASABE 2012 | Year: 2012

The moment magnitude (M) 8.0 earthquake in Wenchuan, Sichuan province, on May 12th, 2008 produced massive landslides made of rock and mud mixture, responsible for serious earthquake-added soil erosion on the impacts of rainfall and runoff. Morphological information of the landslides is needed for estimating the earthquake-added soil erosion. Accurate measurement and calculation of landslide volumes are of great importantances. Typical landslides in Wenchuan County were chosen to estimate their volumes by using 3-D laser scanner of high accuracy. Typical landslides were chosen to measure the relative landslide surface elevation. A method is suggested for the landslide geometry model and for estimating the volume and the morphology of the landslides, based on the measure data. The study established the method and procedures for measuring the volume of landslides with 3-D laser scanner, to supply a sound basis for estimating earthquake-added soil erosion.


Chen Z.,China Agricultural University | Lei T.,China Agricultural University | Yan Q.,China Agricultural University | Hu H.,Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment | Xiong M.,Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment
American Society of Agricultural and Biological Engineers Annual International Meeting 2013, ASABE 2013 | Year: 2013

Wenchuan earthquake produced massive loosen landslides, which have become the main source of earthquake added soil erosion, to threaten the ecological system recovery and the production and livelihood security of the localities. The landslides in Wenchuan Town, Sichuan Province were measured by using 3-D laser scanner. The model of relationship between their horizontal projected areas and volumes were suggested in this study. The accuracy of the scanning was 20.0x20.0 cm at the place 200 m from the scanner. The geometry shape of landslide segmented was approximated as tetrahedron. The measurements of five typical landslides were used to calibrate a model to link landslide horizontal projected area to the volume. The model was verified by using Cyclone 6.0 software. This estimation model supplies an important basis for earthquake-added soil erosion forecast and volume estimation of earthquake area landslide by using remote-sensing image.


Chen Z.,China Agricultural University | Lei T.,China Agricultural University | Yan Q.,China Agricultural University | Hu H.,Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment | And 2 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2014

This paper describes a new method for determining the amount of earthquake-added soil erosion in Wenchuan earthquake area. To study on the method, typical landslides were chosen in Wenchuan County, and the information of typical landslide surface and its surrounding terrain were obtained by on-site measurement. The rill/gulley on the landslides were identified by image analysis, and the amounts of slope erosion from landslides were estimated by numerical calculation. The on-site measurement was carried out by using a 3-D laser scanner (HDS3000, Leica Company). The scanning distance reached as far as 300 m, with a distance measurement accuracy of ±4 mm at 50 m. The scanner was set up in front of the slope of the landslide to be measured. The distances from the scanner to near end and the far end of the landslide were 58.32 m and 136.81 m respectively. The scan grid was set to 20.0 cm horizontal and 20.0 cm vertical at 200 m from the scanner. The actual scan grid of the measured landslide was 5.8 cm×5.8 cm at the near end and 13.7 cm×13.7 cm at the far end, respectively. Landslides surfaces sections prior to erosion were specified by using least squares curve fitting method, and fitting it with curve of the second degree. The gully volume was estimated by comparing the result of surfaces prior to erosion and on-site data collected with laser scanner. The erosion volume of a typical landslide surface gully from 2008 to 2012 was estimated to be 355 m3. The method was verified with the data calculated by traditional cross section area method. The cross sections area and length of gully were calculated by the built-in method of the 3-D laser scanner. The result showed that the values calculated by the method suggested were a little bigger than that by the traditional cross section area method. The relative error of the method was 15.6% for the whole gully, with the lowest being 7.9% and the highest being 27.1% for the segmentations. The reasonable accuracy of the method showed that the rill/gully volume of landslide could be estimated reliably by using it in engineering application.


Chen Z.,China Agricultural University | Lei T.,China Agricultural University | Lei T.,Chinese Ministry of Water Resources | Yan Q.,Chinese Ministry of Water Resources | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

The earthquake of moment magnitude (M) 8.0 in Wenchuan, Sichuan Province, on May 12th, 2008 produced massive loose landslides, responsible for failure of agricultural land and damage of farmland facilities, which caused a heavy loss of agricultural economy and threatened the production security of agricultural in earthquake area. In this study, typical landslides were chosen to measure volumes with geometry models. The landslide in Caopo Village, Wenchuan County, as measured by using 3-D laser scanner, was used to do measurement and computational processes. The 3-D laser scanner is HDS-ScanStation2, Leica Company, and its scanning distance reaches as far as 300 m, with an distance measurement accuracy of ±4 mm and a resolution of ±6 mm at 50 m. The scanner was set up in front of the slope of the landslide to be measured. The distances from the scanner to the near end and the far end of the landslide were 25.74 m and 79.00 m, respectively. The scan grid was set to be 20.0 cm in horizontal and 20.0 cm in vertical. The actual scan grid of the measured landslide was 2.6 cm×2.6 cm at the near end and 7.9 cm×7.9 cm at the far end, respectively. The landslide surface and its surrounding terrain were accurately scanned on-site by the 3-D laser scanner. The measured landslide was divided into two parts according to its scanned surface features. The original terrain data of the valley were used to determine the bottom planes of the landslide, including horizontal and the hillslope. The horizontal boundary was determined by the original landscape and hillslope bottom was approximated by fitting the hillslope. Based on the data points measured by scanner, the planes were fitted with eigenvalue method. The geometry model of landslide was formulated in the 3-D coordinate system by the measured data. The volume of the landslide was estimated to be 19018 m3. The method was verified with the value calculated by the built-in method of the 3-D laser scanner. The result shows that the value calculated by the method suggested was 7.3% higher than that by the build-in method. The reasonable accuracy of the method shows that the volume of landslides can be measured reliably by the method. The method and procedures for measuring the landslide volume with 3-D laser scanner provide an important basis for methods and measures of land consolidation of earthquake damaged farmland after the disaster.

Loading Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment collaborators
Loading Sichuan General Monitoring Station of Soil and Water Conservation Ecological Environment collaborators