Monitoring sandified land changes using multi-temporal Landsat TM/ETM+ Data in Dengkou County of Inner Mongolia, China

Monitoring sandified land changes using remote sensing provides accurate and timely information for prevention and control of sandified lands. Using Landsat TM/ETM+ Data, this paper detected and monitored sandified land changes from 1992 to 2002 in Dengkou County of Inner Mongolia, China, which was a typical region suffering from land degradation and sandstorm hazard in arid and semi-arid areas. A hybrid method combining principal component analysis (PCA) and supervised classification was employed to detect sandified land changes. All the bands from two dates of Landsat TM/ETM+ images were merged into a twelve-band image on which PCA was undertaken. The second principal component (PC2) appropriately reflecting sandified land changes was chosen for change detection. The thresholds were applied to PC2 image to isolate the pixels that had changed. Supervised classification was used to classify the change areas. The hybrid method was very useful in identifying the extension or reversion of sandified lands. Results showed that the total area of sandified lands in Dengkou County decreased by 24.47% during the study period, while shifting sandy lands increased by 21.5%. Caused by human activities, especially over-reclamation, most of decreased sandified lands were converted into farmlands, and farmlands increased by 70.7%. The paper could provide scientific basis for decision making and action taking of sandified land control.