ZHAO Dan, ZHANG Miao, YU Mingzhao, et al. Monitoring agriculture and forestry recovery after the Wenchuan Earthquake. [J]. Journal of Remote Sensing 18(4):958-970(2014)
ZHAO Dan, ZHANG Miao, YU Mingzhao, et al. Monitoring agriculture and forestry recovery after the Wenchuan Earthquake. [J]. Journal of Remote Sensing 18(4):958-970(2014) DOI: 10.11834/jrs.20143345.
Monitoring agriculture and forestry recovery after the Wenchuan Earthquake
The 8. 0 MsWenchuan Earthquake in 2008 significantly damaged the local ecosystem of Sichuan Province. In this study
high spatial resolution airborne remote sensing images
spaceborne remote sensing data
and field investigations were used to monitor and analyze agriculture and forestry recovery in Sichuan Province in the five years after the earthquake. The remote sensing i mages were acquired from the"Wenchuan 5th Anniversary"flight campaign organized by the Institute of Remote Sensing and Digital Earth
Chinese Academy of Sciences. For the agricultural aspect
visual interpretation by using high-resolution airborne i mages acquired from 2008 to 2013 and expert experience were used to determine the status of damaged cultivated areas and to e valuate their recovery.Crop type proportions were collected through ground surveys by using a GVG( GPS
Video
and GIS) i nstrument over a sampled area
and then
interpolated for regions that were not surveyed. Results revealed that only 17. 5% of the 1592 ha damaged arable land could be cultivated five years after the Wenchuan Earthquake. Nearly all usable arable land was cultivated and the cropping structure did not evidently fluctuate after the earthquake. The enthusiasm of local farmers toward their craft was not affected by the u nprecedented disaster. This study recommends that the cropping structure must be kept essentially constant to ensure the supply of food in the disaster area. For the forestry aspect
the recovery of three key areas( which are distributed in the dry valley of the M injiang River area and the montane around the Sichuan Basin area) was monitored via visual interpretation of airborne images. The damage and the recovery status of the entire disaster area were assessed by conducting a time-series change analysis of the normalized difference vegetation index with data from the Moderate-Resolution Imaging Spectroradiometer( MODIS). The results showed that the recovery status of forests in the key areas is relatively good
given that shrubs and young d eciduous trees are g erminating in most parts of the forests that were destroyed by landslides and mud-rock flows. However
some severely destroyed areas with large slopes and areas that were frequently struck by secondary disasters are still encountering difficulties. In summary
the 46400 ha seriously damaged and the 177000 ha moderately damaged forest areas have fully recovered by 13. 52% and 25. 84%
respectively
and both have partly recovered by approximately 50%. Some severely destroyed areas
which mainly include the f orest areas around Chaping Mountain
require physical intervention to accelerate recovery. A change analysis can directly indicate the damage and recovery status of croplands and forests by using high-resolution airborne images. The airborne remote sensing sensor will continue to play an important role in monitoring ecosystems and in assessing important natural disasters. Meanwhile
a time series analysis can monitor damage and recovery of forests at a large scale by using MODIS data.
关键词
汶川地震农林恢复机载高分辨率遥感影像目视解译变化检测
Keywords
Wenchuan earthquakeagriculture and forestry recoveryairborne high-resolution remote sensing imagesvisual i nterpretationchange detection