Study on Oasis Soil Salinization in Xinjiang Based on Quantitative Remote Sensing
Soil salinization is an important worldwide environmental problem, especially in arid and semi-arid regions.Knowledge of its temporal and spatial variability is crucial for the management of oasis agriculture. Yutian County was selected for this study because of its importance as a significant site for agricultural development. Located in the south of the Keriya oasis, it has recently been exposed to severe soil salinization. Thematic Mapper-plus(ETM+) images dated October 7, 2002 were used against the data of soil features obtained from field investigation and analysis of typical soil information, to extract Salinization Index (SI) and land surface albedo, which are very important biophysical parameters of land surface. In this paper the relationship between salinization index (SI) and albedo was analyzed quantitatively.Through experiment and theoretical reasoning, the author proposed a conception of SI-Albedo space and discussed its biophysical characteristics. Analysis revealed that location could be used to improve the current strategies for salinization in the SI-Albedo space, and hence the strategies for salinization mapping, by defining measurements in this feature space.An information extraction model, using the decision-tree classification method, was established and applied to classification of RS images. Results indicate that the classification based on SI-Albedo space has a higher classification accuracy than the one based on maximum likelihood. Its highest overall-accuracy is about 0.921 4% higher than theaximum likelihood. Although both techniques show some mix-class phenomena in the classification result, but the classification based'on SI-Albedo space has less than the maximum likelihood, and thus a higher separability. Based on the salinized soil map, the salinity soil early-warning line was derived for anticipating further soil degradation. Such contrasting and complementary behavior suggests a potential synergism between salinization index and land surface albedo for mapping and monitoring of a complex soil salinization environment such as Keriya oasis.
NETL
NSTL
万方数据
维普
