Study On Numerical Periglacial Geomorphology Extraction Method Based On Remote Sensing And DEM In Qinghai-Tibet Plateau

Geomorphology is one of the most predominant components of physical geography environment. It directly influences and even decides the distribution and change of ecological and environmental factors. So it becomes one of the key and fundamental research fields in geography. Periglacial geomorphology is a kind of important geomorphology, which has close relation with global climate change, the distribution and exploitation of new energy (such as natural gas hydrate) and the construction of roads. Qinghai-Tibet Plateau becomes a big interest in research, which has big area and high elevation with 4000～5000m, and is called the global "third pole". Periglacial geomorphology is one of the most important and wide distributing geomorphology. Hence, study on numerical periglacial geomorphology extraction method based on remote sensing and DEM in Qinghai-Tibet Plateau has big significance.At first, this paper models and extracts the distribution of periglacial geomorphology in Qinghai-Tibet Plateau by using two methods as follows:(1) At first, the extraction of distribution of periglacial geomorphology in Qinghai-Tibet Plateau by using DEM and longitude and latitude data gets the lower boundary of periglacial geomorphology by using latitude raster data and modeling formula. Then the elevation of snow line (the upper boundary of periglacial geomorphology) is acquired by using the snow line elevation of observation stations around Qinghai-Tibet Plateau through the method of Inverse Distance Weighted Interpolation. Finally, the rough boundary of periglacial geomorphology is achieved by using the Digital Elevation Model and the lower and upper boundary of periglacial geomorphology in Qinghai-Tibet Plateau.(2) The extraction of distribution of periglacial geomorphology in Qinghai-Tibet Plateau by using annual mean temperature studies the mean temperature of the lower and upper boundary of periglacial geomorphology. Then the annual mean temperature of the boundary of periglacial geomorphology is acquired (-6.5℃and -2.5℃separately). Then the lower and upper boundaries of periglacial geomorphology are modeled and extracted. So the rough boundary of periglacial geomorphology in Qinghai-Tibet Plateau is achieved by annual mean temperature.Base on the remote sensing images, the extracted boundary of periglacial geomorphology in Qinghai-Tibet Plateau is revised by using expert knowledge. So the exact boundary of the periglacial boundary is achieved. Then the extracted boundaries of the two methods and the revised boundary are compared, evaluated, analyzed and discussed.Based on the known distribution of periglacial geomorphology, the interpreting marks of periglacial geomorphology in Qinghai-Tibet Plateau are built by using remote sensing images and DEM. The establishment of remote sensing interpreting marks provides a basis and qualification for the revision, correction of the extracted results of morphological features of periglacial geomorphology in Qinghai-Tibet Plateau and the interpretation of periglacial geomorphology in Qinghai-Tibet Plateau.Then, taking the district of 1:1,000,000 international standard of Lhasa map sheet (serial number h-46) as a test area, we study the extraction of periglacial geomorphology. After the acquirement of the distribution of periglacial geomorphology in test area, the morphological indexes of periglacial geomorphology such as the boundary of plain and mountain, elevation, relief, slope and so on are modeled and extracted by using DEM. Then the indexes are revised and corrected by interpreting marks, remote sensing images and geomorphological knowledge. The final results of indexes are achieved so that semi-automatic remote sensing extraction and interpretation of periglacial geomorphology combined with the cause and morphology in test area comes true. The extracted results of periglacial geomorphology are evaluated and discussed.Finally, based on the above, the distraction results of periglacial geomorphology in Qinghai-Tibet Plateau are achieved. The analysis of spatial distribution characters of periglacial geomorphology provides a foundation for its interpretation and has special reference to its research.This research not only boosts the development of study of geomorphology (especially periglacial geomorphology) in Qinghai-Tibet Plateau, but also promotes the application of remote sensing auto-interpretation to geomorphology research. So it improves the efficiency of remote sensing in geomorphology, reduces the labor intensity and provides a reference to the interpretation of other kinds of geomorphologies.