RESEARCH ON THE INFORMATION EXTRACTION OF PERIGLACIAL GEOMORPHOLOGY IN QINGHAI-TIBET PLATEAU

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1 RESEARCH ON THE INFORMATION EXTRACTION OF PERIGLACIAL GEOMORPHOLOGY IN QINGHAI-TIBET PLATEAU Zhao Shagmi a, b, *, Cheg Weimig b, Zhou Cheghu b, Che Xi a a Xijiag Istitute of Ecology ad Geography Chiese Academy of Scieces, Urumchi, Xijiag, Chia, zhaosm@lreis.ac.c, chexi@ms.xjb.ac.c b State Key Laboratory of Resources ad Evirometal Iformatio System, Istitute of Geographic Scieces ad Natural Resources Research, CAS, Beijig , Chia (zhaosm, chegwm, zhouch)@lreis.ac.c Commissio VIII, WG VIII/12 KEY WORDS: Image Iterpretatio, Digital Elevatio Models (DEM), Image Uderstadig, Feature Extractio, Geomorphology, Qighai-Tibet Plateau ABSTRACT: Takes Qighai-Tibet Plateau as a research field, this paper based o the models ad algorithms, completes the umerical iformatio extractio of periglacial geomorphology distributio by usig SRTM-DEM ad aual mea temperature data. Based o the extracted results ad remote sesig images, the periglacial geomorphology distributio i Qighai-Tibet Plateau is achieved by visual iterpretatio. Accordig to the visual iterpretig results, the quality ad precisio of the extracted iformatio are discussed ad aalysed. Fially, o the foudatio of the 4 permafrost regios i Qighai-Tibet Plateau, the quality ad precisio of the extracted iformatio of periglacial geomorphology are studied accordigly; takig Massive Cotiuous Permafrost Regio i Qiagtag Plateau as a example, the quality ad precisio of the extracted results i this area are aalyzed specifically. 1. INTRODUCTION With vast area ad high altitude of 4000~5000m, Qighai-Tibet Plateau Locatig i southwester Chia is oe of the most importat geomorphological uits i Chiese terrestrial part. Because of its high altitude, vast area, harsh climate ad the mid-latitude locatio, kow as the third pole of the earth, it has close correlatio with the biggest mosoo system o the globe which has ot oly sesitive respodig character but sigificat impact to the global climate chage (Liu Tugsheg, et al, 1999). Hece it becomes oe of the hot spots of research. Geomorphology is oe of the most predomiat compoets of physical geography eviromet. It directly iflueces ad eve determies the distributio ad chage of ecological ad evirometal factors. So it becomes oe of the key ad fudametal research fields i geographical scieces (Cheg Weimig, 2005). Periglacial geomorphology is a kid of earth surface form which results from periglacial process such as frost weatherig ad freeze-thaw process; it maily distributes i harsh climate regio but without covered by glaciers. Various kids of stoe ad soil which cotais ice ad whose temperature is ot above 0 is called geocryology. The geocryology whose freezig state keeps more tha several years or more tha several thousad years is called permafrost. Permafrost is divided ito cotiuous permafrost ad discotiuous permafrost. Geological process ad pheomeo of geocryology are geerally called periglacial process ad shape (Zhou Youwu, et al, 2000). I additio, the distributio of periglacial geomorphology is approximate to it of geocryology, so periglacial geomorphology is also called geocryology (Zhou Cheghu, 2006). Periglacial geomorphology is a widely distributig ad oe of the most importat geomorphology types i Qighai-Tibet Plateau, which has close relatio to global climate chage, the distributio ad exploitatio of ew eergy sources (such as atural gas hydrate), road costructio ad so o (Wu Qig-bai, et al, 2006; Wag Gexu, et al, 2008). With the rapid developmet of remote sesig techology, it has more ad more applicatio i most atioal ecoomic departmets. Hece, geomorphology research by usig remote sesig techology becomes a importat topic i geomorphology research. SRTM-DEM data is used to depict the groud altitude i every place, which has broad applicatio i geographic research (G. Jorda, et al, 2005). Therefore, research o the umerical extracted method of periglacial geomorphology i Qighai-Tibet Plateau has importat sigificace. 2. RESEARCH AREA SITUATION AND INFROMATION SOURCE I this part, the geeral situatio of research area is described at first. The, the iformatio source i this research is discussed. They are the foudatio to carry out this research. 2.1 Research area situatio Kow as its low latitude, high altitude ad particular harsh climate, Qighai-Tibet Plateau locatig i Asia Cotiet is the most widely distributig area of periglacial geomorphology i Chia. I Chia, its boudary from west to east is from Pamirs to Hegdua Moutais ad the legth is about 2945km; the boudary from south to orth is from souther edge of Himalayas to orther side of Kulu Moutais ad the width is about 1532km. The boud of Qighai-Tibet Plateau is 26º00 12 N~39º46 50 N, 73º18 52 E~104º46 59 E. The area is about km 2, which accouts for about 26.8% of total area of Chia (Li Bigyua, 1987; Zhag Yi-li, 2002). 1251

2 The distributio of geocryology is approximate to it of periglacial geomorphology, which is divided ito 4 parts i Qighai-Tibet Plateau. They are: Alpie Permafrost i Qilia Moutais-Altu Rage locatig i ortheast part, Massive Cotiuous Permafrost i Qiagtag Plateau locatig i orthwest part, Alpie Sporadic Permafrost i Niajigtaggula Hill ad Himalayas locatig i southwest part, Sporadic Permafrost i Souther Moutai Plateau ad Easter Moutai locatig i southeast part (BAOLAI WANG, et al, 1995). The specific distributio is show as i Figure 1. The climate of Qighai-Tibet Plateau is trasited from oceaic climate to cotietal climate gradually alog the southeast to orthwest directio. Hece, Alpie Sporadic Permafrost i Niajigtaggula Hill ad Himalayas ad Sporadic Permafrost i Souther Moutai Plateau ad Easter Moutai are mostly cotrolled by oceaic climate ad the other two parts by cotietal climate. Figure 1. Froze Groud of the Qighai-Tibet Plateau ad the study area (referece the map of sow, ice ad froze groud i Chia by Shi Yafeg, 1988) 2.2 Iformatio source I this research, the mai iformatio source are ETM ad TM images acquired by USA Ladsat satellites, SRTM-DEM digital elevatio model data ad aual mea temperature data obtaied by stadard statios of Chia (ZHAO Shag-mi, et al, 2007). The remote sesig images are TM images collected i 1990 summer ad ETM images i 2000 summer. The spatial resolutio is 30m ad the format is img. They are artificial multicolour compouded images ad compouded by the bads of 7, 4 ad 2. The compouded images have good quality ad abudat iformatio, which is beefit for the iterpretatio of geomorphology type. SRTM-DEM is digital elevatio model data, whose format is grid. SRTM-DEM data records the elevatio iformatio of every pixel i the research area, ad the pixel is 90m. The geomorphic form iformatio such as relief, elevatio, slope ad aspect i research area ca be computed by usig SRTM- DEM data, so SRTM-DEM data plays a importat role i acquaitig the groud form characteristics. Based o more tha 600 observatio statios data i Chia ad through the method of regressio equatio + residual error, aual mea temperature data is rasterized ad obtaied by usig the liear correlatio amog temperature, latitude ad altitude. The aual mea temperature data i research area ca be achieved by clippig the data of Chia. 3. METHODS AND RESULTS Firstly, this research extracted the periglacial geomorphology distributio i Qighai-Tibet Plateau by usig SRTM-DEM data ad aual mea temperature data respectively. Based o the extracted results, the periglacial geomorphology distributio is iterpreted by usig remote sesig images ad other data. The the compariso betwee extracted results ad iterpreted result is carried out. Fially, based o the distributio of 4 permafrost regios i Qighai-Tibet Plateau, the precisio ad quality of every result i differet permafrost regios are studied ad discussed. 3.1 Study o the distributio of periglacial geomorphology i Qighai-Tibet Plateau Because the distributio of permafrost is approximate to it of periglacial geomorphology, so the distributio of permafrost is extracted to replace the distributio of periglacial geomorphology i some cases. At first, the distributio of permafrost regio i Qighai-Tibet Plateau is extracted by SRTM-DEM digital elevatio model data ad aual mea temperature data respectively. The, accordig to the remote sesig images ad visual iterpretatio experiece, the periglacial geomorphology distributio i Qighai-Tibet is achieved by referecig the extracted results. Geerally speakig, the iterpreted result is better tha the extracted results i both precisio ad quality. Cosequetly, we evaluate the precisio ad quality the extracted results based o the iterpretig results at last Distributio extractio of periglacial geomorphology i Qighai-Tibet Plateau by usig SRTM- DEM data: To extract the distributio of periglacial geomorphology, the mai aim is to acquire the elevatio rage of periglacial geomorphology distributio aywhere i Qighai- Tibet Plateau. That is, to acquire the lower ad upper limits of the distributio of periglacial geomorphology. The lower limit of periglacial geomorphology distributio is approximate to it of permafrost distributio, so we extract the lower limit of permafrost distributio to istead. The upper limit of periglacial geomorphology distributio is the elevatio of sow lie. As to the elevatio of lower limit of permafrost distributio, Cheg Guodog holds that the distributio of permafrost i Qighai-Tibet Plateau has obvious zoality law of three directios (latitude directio, logitude directio ad vertical directio), so the relatio betwee the elevatio of lower limit of permafrost distributio (H) ad latitude (φ) ca be expressed by the followig Gauss distributig fuctio (Cheg Guodog, et al, 1983, 1984, 2000; Wu Qig-bai, et al, 2000): H = 3650exp[-0.003(φ-25.37) 2 ]+1428 (1) where H = the lower limit elevatio of permafrost distributio φ = geographical latitude The scholars such as Dig Dewe ad so o also studied the lower limit elevatio of permafrost distributio i Qighai- Tibet Plateau (Dig Dewe, et al, 1982). After sythesizig 1252

3 aalyse, experimetatio ad research, we choose to extract the lower limit by usig the method of Cheg Guodog. The upper limit of periglacial geomorphology i Qighai-Tibet Plateau is the elevatio of sow lie. The scholars such as Jiag Zhogxi ad so o had studied the elevatio of global sow lie (Jiag Zhogxi, 1984). Cosiderig the terrai particularity of Qighai-Tibet Plateau, however, it is better to obtai the sow lie elevatio by iterpolatig the sow lie elevatio data measured by observatio statios i ad aroud Qighai-Tibet Plateau. The iterpolatio method is Iverse Distace Weighted Iterpolatio, whose idea is the distace to the iterpolated poit is farther, the effect is less. It is iterpolated by the power of the reciprocal value of the distace. The iterpolatio equatio is as follows (Che Shupeg, et al, 1999): ad geocryology, 1988). Accordig to the literatures ad experimets, the aual mea temperature data rage of periglacial geomorphology distributio everywhere is ot exactly the same, but the geerally rage is betwee -6.5 ad Hece, if the regio where the aual mea temperature is betwee -6.5 ad -2.5 is extracted, the distributio of periglacial geomorphology i Qighai-Tibet Plateau is achieved accordigly. The extracted result is show as i Figure 3. f ( x, y) i= 1 = 1/ d i= 1 i 1/ d Z i, =1 or 2 (2) i where d i = the distace betwee the iterpolated poit ad the kow data Z i = the value of the i kow poit = the power f (x, y) = the value of the iterpolated poit Now that the sow lie elevatio i Qighai-Tibet Plateau has bee calculated, the upper ad lower limit of periglacial geomorphology distributio everywhere has bee worked out. So the periglacial geomorphology distributio i Qighai-Tibet Plateau ca be extracted by usig SRTM-DEM data. The extracted map is show as Figure 2. Figure 3. The extracted result of the distributio of periglacial geomorphology by usig aual mea temperature data Distributio acquisitio of periglacial geomorphology i Qighai-Tibet Plateau by visual iterpretatio: Visual iterpretatio is a method to acquire iformatio from remote sesig images by iterpretatio marks ad experieces. Because the visual iterpretatio results referece the previous maps ad achievemets ad are completed by expert kowledge ad judgemet, so the quality ad precisio of the iterpretatio result are much better tha the extracted results. I this research, based o the extracted results by SRTM-DEM data ad aual mea temperature data, we iterpret the distributio of periglacial geomorphology i Qighai-Tibet Plateau by usig remote sesig images, other maps ad data, iterpretatio marks ad iterpretig experieces. Through field ivestigatio, validatio ad revisio to the prelimiary iterpreted result, the fial result by visual iterpretatio is achieved. It is show as i Figure 4. Figure 2. The extracted result of the distributio of periglacial geomorphology by usig SRTM-DEM data Distributio extractio of periglacial geomorphology i Qighai-Tibet Plateau by usig aual mea temperature data: The elevatio of Qighai-Tibet Plateau is about 4000~5000m, which provides the coditio of the harsh climate to the formatio of periglacial geomorphology ad creates uique periglacial eviromet for the growth of various frost process ad the geeratio of plateau geomorphology. Accordig to the research, the coditio of the existece of periglacial geomorphology is that the aual mea groud temperature is less tha 0. As the aual mea groud temperature ca ot be obtaied easily, so we take aual mea air temperature to replace it (Lazhou istitute of glaciology Figure 4. The iterpretatio result of the distributio of periglacial geomorphology i Qighai-Tibet Plateau As the result by visual iterpretatio has better quality ad precisio, so we ca estimate the precisio ad quality of the 1253

4 extracted results by SRTM-DEM data ad aual mea temperature data based o the iterpreted result Estimatio to the precisio ad quality of the extracted results: Compared to the extracted results of the distributio of periglacial geomorphology i Qighai-Tibet Plateau obtaied by various methods as show i Figure 2, Figure 3 ad Figure 4, the coclusios are as followig: (1) The extracted results of periglacial geomorphology distributio i Qighai-Tibet Plateau by usig SRTM-DEM data ad aual mea temperature data are geerally exact, which ca reflect the distributio of periglacial geomorphology well. So the extracted results ca provide a good basis for visual iterpretatio. (2) The quality ad precisio of the extracted results are ot the same i differet place i Qighai-Tibet Plateau. Accordig to the 4 permafrost regios i Qighai-Tibet Plateau, the precisio of the extracted results i Alpie Permafrost i Qilia Moutais-Altu Rage ad Massive Cotiuous Permafrost i Qiagtag Plateau is better tha it i other two permafrost regios. The compariso of the two extracted results i the east district of Qaidam Basi is show as i Figure 5. The grey backgroud i Figure 5 is the distributio obtaied by visual iterpretatio. From Figure 5 we ca see that i some place the extracted results are similar ad exact. I additio, they are approximate to the fial iterpretig results. Hece, they ca play a import role i visual iterpretatio. (1) (2) Figure 5. Compariso betwee the two extracted results (1. by SRTM-DEM data; 2. by aual mea temperature data) (3) The differece of the precisio of the extracted results i various permafrost regios perhaps due to the differet climate types. I the souther part of Qighai-Tibet Plateau, the climate is maily cotrolled by oceaic type; from the southeast to orthwest directio, the climate is gradually trasformed from oceaic type to cotietal type. Differet climate, precipitatio ad temperature result i differet distributio situatio of periglacial geomorphology i Qighai-Tibet Plateau. Hece, it may be oe of the big factors to affect the quality ad precisio of the extracted results. 3.2 Study o the extracted results i differet permafrost regios of Qighai-Tibet Plateau There are 4 permafrost regios i Qighai-Tibet Plateau. The precisio ad quality of the extracted results i differet permafrost regios are ot the same, ad the differece ca ot be eglected. The area of the periglacai geomorphology distributio results i every permafrost regio is show i Table 1. There are some coclusios ca be obtaied from Table 1: Accordig to the total area, the area of the extracted results from SRTM-DEM data ad aual mea temperature data are km 2 ad km 2 respectively, while the area of the iterpreted result is km 2. So the total area obtaied by differet methods is similar. This meas that the extracted results are geerally cosistet with visual iterpretig result ad they ca provide importat basis ad referece for the visual iterpretatio of periglacial geomorphology distributio. I differet permafrost regios, however, the situatio of the extracted result i area is ot the same. I Alpie Permafrost i Qilia Moutais-Altu Rage ad Massive Cotiuous Permafrost i Qiagtag Plateau, the areas of the extracted results by SRTM-DEM data ad aual mea temperature data are bigger tha the area of iterpretig result. Nevertheless, the areas of the extracted results are less tha the area of the iterpretig result i other two permafrost regios. The differece betwee the extracted results ad iterpretig result perhaps dues to the climate chage from the southeast directio to orthwest directio ad the chage of temperature ad precipitatio resultig from the climate chage. Area( 10 4 km 2 ) Alpie Permafrost i Qilia Moutais- Altu Rage Massive Cotiuous Permafrost i Qiagtag Plateau Alpie Sporadic Permafrost i Niajigtaggula Hill ad Himalayas Sporadic Permafrost i Souther Moutai Plateau ad Easter Moutai Extracted result by SRTM-DEM data Extracted result by aual mea temperature data Iterpretatio result Total Area Table 1. The area of differet extracted results i the 4 permafrost regios 1254

5 Takig Massive Cotiuous Permafrost i Qiagtag Plateau as a example area, we make the compariso amog the visual iterpretatio result ad the extracted results of periglacial geomorphology distributio show as i Figure 6. From Figure 6 we ca see that the distributio of periglacial geomorphology is widely distributed i Qiagtag Plateau, especially i the middle part of the Qiagtag Plateau. But both the extracted result from SRTM-DEM data ad the extracted result from aual mea temperature data have obvious less exactess tha the iterpretig result. Comparatively, the quality of the extracted result by SRTM-DEM data is better tha the quality of the result extracted by aual mea temperature data. I additio, the area of the extracted result by SRTM-DEM data is more approximate to the area of the visual iterpretig result tha the extracted result by aual mea temperature data do. quality ad precisio of the extracted results may have a big improvemet. 4. CONCLUSIONS Through the above research, the followig coclusios ca be achieved: (1) Comparig the extracted results by SRTM-DEM data ad aual mea temperature data ad the iterpretig result by remote sesig images ad visual iterpretatio, we ca fid that the extracted results are geerally cosistet with the iterpretig result. Hece, the extracted results ca provide importat basis ad referece for the visual iterpretatio. (2) The quality ad precisio of the extracted results of periglacial geomorphology distributio i Qighai-Tibet Plateau are differet i various permafrost regios. The areas of the extracted results are bigger tha the visual iterpretig result i orther part, but less i souther part. Accordig to the precisio, the precisio of the extracted results is better i orther part tha i souther part compared to the visual iterpretig result. (1) By SRTM-DEM data (2) By aual mea temperature data (3) As the distributio situatio of periglacial geomorphology i Qighai-Tibet Plateau is ot the same i differet permafrost regios, the precisio ad quality of the extracted results will be improved largely by usig differet method i various permafrost regios. (4) The quality of the data sources ad the research level are importat factors to affect the precisio of the extracted results. With the cotiuous improvemet of the data quality ad the advacemet of research level, the quality of the automatic extractio of periglacial geomorphology distributio will be improved accordigly. It will be provide sigificat basis for automatic mappig ad visual iterpretatio of periglacial geomorphology. REFERENCES (3) By visual iterpretatio Figure 6. Compariso of the results by differet methods i Massive Cotiuous Permafrost i Qiagtag Plateau The differece betwee the extracted results ad the visual iterpretatio result ca ot be evitable. The area is oly oe idex to evaluate the quality of the extracted result. I fact, the approximatio of the area ca ot fully guaratee the quality of the extracted results. Other tha the area, the error of other idexes such as the shape ad the locatio are also importat for the precisio of the extracted results. The distributio situatio of periglacial geomorphology i Qighai-Tibet Plateau is differet i the 4 permafrost regios, so the precisio ad quality of the extracted results have differece, too. If we study the distributig rules of periglacial geomorphology i differet permafrost regios deeply ad extracted it by usig differet methods i differet regios, the Refereces from Jourals: BAO LAIWANG, HUGH M. FRENCH, PERMAFROST ON THE TIBET PLATEAU, CHINA. Quaterary Sciece Reviews, 14, pp Cheg Guodog, Wu Bagju, Approach to the Mathematical Model of Zoality of High-Altitude Permafrost. JOURNAL OF GLACIOLOGY AND CROPEDOLOGY, 5(4), pp Cheg Guodog, PROBLEMS ON ZONATION OF HIGH-ALTITUDE PERMAFROST. ACTA GEOGRAPHICA SINCA, 39(2), pp Cheg Guodog, Zhao Li, THE PROBLEMS ASSOCIATED WITH PERMAFROST IN THE DEVELOPMENT OF THE QINGHAI-XIZANG PLATEAU. QUATERNARY SCIENCES, 20(6), pp G. Jorda, B. M. L. Meijiger, D. J. J. va Hisberge, et al, Extractio of morphotectoic features from DEMs: Developmet ad applicatios for study areas i Hugary ad 1255

6 NW Greece. Iteratioal Joural of Applied Earth Observatio ad Geoiformatio, 7, pp Jiag Zhogxi, Quatitative Aalysis of Sowlie Zoality. JOURNAL OF GLACIOLOGY AND CROPEDOLOGY, 6(2), pp Li Bigyua, ON THE EXTENT OF THE QINGHAI- XIZANG (TIBET) PLATEAU. GEOGRAPHICAL RESEARCH, 6(3), pp Liu Tugsheg, Zhag Xishi, Xiog Shagfa, et al, QINGHAI-XIZANG PLATEAU GLACIAL ENVIRONMENT AND GLOBAL COOLING. QUATERNARY SCIENCES, 19(5), pp Wag Gexu, Li Yuashou, Wag Yibo, et al, Effects of permafrost thawig o vegetatio ad soil carbo pool losses o the Qighai-Tibet Plateau, Chia. Geoderma, pp WU Qig-bai, LI Xi, LI We-ju, Computer Simulatio ad Mappig of the Regioal Distributio of Permafrost alog the Qighai-Xizag Highway. JOURNAL OF GLACIOLOGY AND CROPEDOLOGY, 22(4), pp WU Qig-bai, JIANG Gua-li, PU Yi-bi, et al, Relatioship betwee permafrost ad gas hydrates o Qighai- Tibet Plateau. GEOLOGICAL BULLETIN OF CHINA, 25(1-2), pp ZHANG Yi-li, LI Big-yua, ZHENG Du, A discussio o the boudary ad area of the Tibeta Plateau i Chia. GEOGRAPHICAL RESEARCH, 21(1), pp ZHAO Shag-mi, CHENG Wei-mig, CHAI Hui-xia, et al, Research o the iformatio extractio method of periglacial geomorphology o the Qighai-Tibet Plateau based o remote sesig ad SRTM: A case study of 1:1, 000, 000 Lhasa map sheet (H46), Geographical Research, 26(6), pp Refereces from Books: Che Shupeg, Lu Xueju, Zhou Cheghu, Itroductio to Geographic Iformatio System. Sciece Press, Beijig, pp Lazhou istitute of glaciology ad geocryology, Map of Sow, Ice ad Froze Groud i Chia Explaatio. Chia Cartographic Publishig House, Beijig, pp Zhou Cheghu, A Dictioary of Geomorphology. Chia WaterPower Press, Beijig, pp Zhou Youwu, Guo Dogxi, Qiu Guoqig, et al, Geocryology i Chia. Sciece Press, Beijig, pp Refereces from Other Literature: Cheg Weimig, Research o Mappig Methodology of Geomorphology-Lad cover-ladscape Ecology of 1: i chia, Report of Postdoctoral Research, Istitute of Geographic Scieces ad Natural resources Research, CAS, Beijig, Chia, pp Dig Dewe, Xu Xuezu, O Regioalizatio Idexes of Horizotal Distributio of Permafrost i Chia. I: Proceedigs of the Symposium o Glaciology ad Cryopedology held by Geographical Society of Chia (Cryopedology), Sciece Press, Chia, pp ACKNOWLEDGEMENTS This work is supported by the Research o the Extracted Method of the Morphological Characteristics of Typical Geomorphology of the Kowledge Iovatio Program of Chiese Academy of Scieces ad the Experimets o the Geographical Uit Maps Desig Based o Remote Sesig Images of Natioal Surveyig Project of Wester Area without 1:50000 Topographic Maps from Chia. 1256