Differential interferometric synthetic aperture radar (DInSAR) technique has been widely accepted as a powerful tool to map surface deformation. To quantitatively evaluate the surface displacement caused by Wenchuan Earthquake on 12 May 2008 in Sichuan Province, China, a series of interferograms were generated from 25 ALOS/PALSAR image pairs, and the surface displacement was then mapped. According to the wrapped differential interferogram, the main rupture fault was plotted with an orientation of North-East 47° and a spanning length of approximately 230 km. The serious affected region with area of 5,000 km2 and the affected region with area of 250,000 km2 were also mapped. Along the radar look of sight (LOS), it is estimated that the ground surface displaced approximated a maximum of 57 cm and 119 cm away from and towards the satellite respectively, i.e. the vertical displacement was a maximum of 73 cm and 150 cm down lift and uplift respectively. The capability of DInSAR technique and ALOS PALSAR data for co-seismic deformation mapping has been demonstrated and proved to be useful in the surface deformation applications. In addition, some limitations were discussed including the topographic, atmospheric, and orbital errors.
Soil wind erosion is the primary process and the main driving force for land desertification and sand-dust storms in arid
and semi-arid areas of Northern China. Many researchers have paid more attention to this issue. This paper select Inner
Mongolia autonomous region as the research area, quantify the various indicators affecting the soil wind erosion, using
the GIS technology to extract the spatial data, and construct the RBFN (Radial Basis Function Network) model for
assessment of wind erosion hazard. After training the sample data of the different levels of wind erosion hazard, we get
the parameters of the model, and then assess the wind erosion hazard. The result shows that in the Southern parts of Inner
Mongolia wind erosion hazard are very severe, counties in the middle regions of Inner Mongolia vary from moderate to
severe, and in eastern are slight. The comparison of the result with other researches shows that the result is in conformity
with actual conditions, proving the reasonability and applicability of the RBFN model.
Benefiting from southeast monsoon, the red soil hilly region in southeast China has excellent water and heat conditions, and land use here changed rapidly these years. Unreasonable land use, however, resulted in serious ecosystem degradation. Before 1980, most of the zonal vegetation in the study area, mainly consisting of evergreen broad-leaved forest, had been seriously destroyed, and degraded to grassland dominated by perennial grasses with scattered trees and shrubs. At the same time, severe soil degradation also occurred in some places of this region. The ecosystem degradation not only reduces the land productivity, but also has a deep impact on global change. So the restoration and reconstruction of the degraded ecosystems are not only important to the sustainable development of agriculture, but also helpful in understanding the role of this region playing in global change. In this paper, soil nutrient changes in surface horizon (0-20cm) of masson pine woods, wetland pine woods and Chinese fir woods planted in 1984, which are widely planted in the red soil hilly area, were studied. The results showed that Soil Organic Carbon decreased dramatically in the first 10 years, then increased gradually in the following 6 years, and reached to a relative steady status in the latest 5 years, while total nitrogen remained relatively steady, and soil acidification is visible.
Soil erosion is a widespread geological process with strong capabilities to entrap, transport, and redistribute surface soil. It is important to grade erosion intensity and estimate eroded soil mass. On the other hand, soil organic carbon pool (SOC), as the largest terrestrial carbon content, is prone to be affected by soil erosion. Soil erosion redistributes surface soil over landscape, and changes the physical environmental conditions. The consequences are depletion of SOC in eroded regions, emission of carbon dioxide during transportation and input of extra SOC in deposited sites. This paper quantified the effects of soil erosion on soil organic carbon through following three steps: firstly, soil erosion type and soil erosion intensity was determined by interpreting Landsat TM images. Secondly, through field investigation, soil type and soil profile data were collected, and SOC contents in the 0-20cm layers were constructed. Finally, supported by map algebra in Geographic Information System (GIS), soil organic carbon loss induced by soil erosion was calculated based on the national soil erosion modulus standard. Total annual SOC loss in China was about 1.595×108 ton−C yr−1. Assuming 20% of SOC was oxidized, erosion induced CO2 emission was about 3.19×107 ton−Cyr−1.