GEOMORPHOMETRY OF THE GLACIAL CIRQUES IN ZARDKUH MOUNTAIN, IRAN

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1 Annals of Valahia University of Targoviste. Geographical Series (2016), 16(2): DOI: /avutgs ISSN (Print): , ISSN (Online): GEOMORPHOMETRY OF THE GLACIAL CIRQUES IN ZARDKUH MOUNTAIN, IRAN Ali Ahmadabadi 1, Varduhi Sargsyan 2 1 University of Kharazmi, Iran 2 University of Kharazmi, Department of Geomorphology, College of Geography, Iran sarkisian.vart@gmail.com (corresponding author) Abstract Cirques as one of the glacial erosional forms are suitable indicators to recognize the environmental conditions of the Quaternary period. Therefore, considering the importance of glacial cirque landforms, identifying and mapping the distribution of the circus with their shape features meets the need of environmental science, especially geomorphology. In this paper, in order to identify the quantitative features of cirques in Zardkuh region, the second derivatives, including second-degree curvature of the plan, profile and general curvature along with slope as a primarily derivative were used from geomorphometry indices. To this end, 20 meter resolution digital elevation model was generated from 1: 25,000 topographic map which was used in the geomorphometric analysis. The result shows that secondary derivatives had higher performance in identifying the feature shapes of glacial cirques. Likewise, the plan curvature Index could truly present the headwall around the circus as well as profile curvature clearly showed the avalanche path. In conclusion, it seems that the second derivative indicators, including curvature's family, have high capability to extract and detect different natural shapes from digital elevation data. Keywords: Geomorphometry features, Glacial cirque, curvature, Zardkuh. 1. INTRODUCTION Landforms are the base of the geomorphology studies, therefore, researchers based on their purpose classified land surface by different definitions. Glacial cirques as a typical landform had several definition about the formation, development, and distribution. As defined by Evans and Cox (Evans, 1974) a cirque is a hollow, open downstream but bounded upstream by the crest of a steep slope ( headwall ) which is arcuate in plan around a more gently-sloping floor. It is glacial if the floor has been affected by glacial erosion while part of the headwall has developed subaerially. ). The cirque floor is situated between the headwall and an accumulation area. The headwall is defined as a location limited by the border between the gentle and steep slopes at the top and the schrundline at the bottom (Vilborg, 1977, 1984). Geomorphometry is the science of quantitative land-surface analysis (Pike,1995, 2000; Rasemann, 2004). It is also known under names like Digital Terrain Modelling/Analysis and/or relief analysis. Geomorphometry is a modern, analytical-cartographic approach to representing bare-earth topography by the computer manipulation of terrain height (Tobler, 1976, 2000). Cirques are complex features, thus according to their degree of development reflected in their morphology, they have been classified. A number of classification systems have been proposed (e.g., de Martonne, 1901; Rudberg, 1952; Vilborg, 1984), but the most widely used are presented by Evans and Cox (1995). Evans (2006) suggested that cirque floors have a mean slope smaller than 20 and slope of head walls are generally above 33.The described definition of cirques along with the classified slope map extracted from DEM (based on a suggestion of Evans, 94

2 2006) could help us to deliminate the cirque-like features and define boundaries of the headwall and the floor of it. 2. REGIONAL SETTING The Zardkuh Mountain lies along the central Zagros Mountain Range in ChaharMahal and Bakhtiari province. The Zagros Mountain range is a branch of the Alpine-Himalayan orogenic belt and has formed three major mountains named Zardkuh, OshtoranKuh, and Dena. The morphology of the region is directly relevant to its geological and structural features. Accordingly, the most exposed geological formations are Cretaceous and Oligo-Miocene limestone, marlstone and marl limestone with NW-SE general trends. The high relief region is composed of Cretaceous limestone, which is the most resistant formation in the region. The highest summit of this mountain chain is the Zardkuh summit (or Shahe Shahidan) with 4220 m altitude according to the National Cartographic Center of Iran (2010). Fig 1. Study area A few small glaciers (mostly cirque glaciers) were first observed on the northern slopes of Zardkuh during August 1933 (Desio, 1934). Wright (1962) noted the cirques on Zardkuh having altitudes about 3000 m a.s.l., moraines located in small valleys on the north slopes of the Zardkuh with 2600 m a.s.l. altitude, and the large outwash fan at the north slope of the mountain. Grunert et al. (1978) described and sketched the location of five glaciers. The largest was described as 500 m wide and spanning 150 m height from 3900 to 4050 m a.s.l. Preu (1984) has reported two small glaciers in the cirques on the lee side of Zardkuh surrounded by moraine deposits. Also, he mentioned small recent glaciers in some valleys on the north slopes of Zardkuh. Ferrigno (1988) has shown that the glaciers in Zardkuh had thinned considerably and the toe had receded at least 20 m of the total 100 m elevation it formerly spanned. Yamani (2007) outlined 15 glacial cirques in 3400 and 4000 m a.s.l. altitudes of the north slope of Zardkuh. He has also pointed out glacial moraines with an altitude about 2500 m a.s.l. Referring to his study, the height of the modern snowline is above 4800 m a.s.l. He has also mentioned some old alluvial fans located in the outlets of some glacier basins. Moussavi et al. (2009) prepared a new glacier inventory for the glaciers of Iran (according to GLIMS guidelines and remote sensing supported by fieldwork). Based on their research, the greatest glacier concentration in Zardkuh is observed around 1) Joft-zarde and Shahe Shahidan (Zardkuh) summits, 2) around Sirdan summit and 3) around Haft-tanan (Iluk) region with a total surface ~20 km2. Seifi et al. (2014) studied the morphometry of Zardkuh cirques indicated that Zardkuh has been developed allometrically in three dimensions, i.e. more in length and width than in altitudinal range. Ahmadabadi and Sargsyan (2016) studied the geomorphometric features of Zardkuh cirques and extract them automatically. 95

3 3. MATERIAL AND METHODS For Landscape curvature, there are numerous equations and definitions in the literature. There are two broad approaches made by Evans and the Zevenbergen & Thorne. Both use a 3-cell x 3-cell moving window to calculate curvature from the 9 raster cells in the window from raster digital elevation models. There are many types of curvatures like profile curvature, plan curvature, tangential curvature, longitudinal curvature, cross - sectional curvature, maximum curvature, minimum curvature, mean curvature, general curvature. In order to obtain curvature rasters, we used 20-meter accuracy DEM derived from the SRTM altimetry data. Fig 2. Location of cirques no 1,2,3 and 4. Fig 3. Slope map of the studying area 96

4 A D B C Fig 4. Google Earth image of cirques 4.RESULT This study is a preliminary research and presents only the first results of the application of a semi-automated method for glacial cirques curvature delineation based on DEMs in Zardkuh region. In this case, the locations of glacial cirques were manually identified based on 1:25,000 topographic map and re-checked on Google Earth. The slope map of the area was produced from 20m spatial resolution DEM (using 3D Analyst Tools) then as per Evans (2006) suggestion, we considered the slope break line between the floor and headwall of the cirques. By using Terraria Topographic Modeling tool on ENVI we generated curvature raster from the DEM and analyzed them in ARC Map. The curvature of the cirques along with floor curvature was computed separately. 97

5 A B C D Fig 5. Profile graph of cirques Table 1 shows the result of the each cirques curvature parameter. The result of cirques curvature analyses in Zardkuh shows positive profile curvature which shows convex surfaces, whereas plan curvature is negative showing divergence surfaces. As well the result shows that we have negative values for Min. and Long. curvatures. It is notable that general and cross.-sec. curvature due to being near to zero value has small positive and negative values. Moreover, we can see from the result that cirques B and D shows near mean values in slope, plan, min and general curvature parameters which are showing the resemblance of the cirques. The Same happens for cirques A and C. In table 2. is showing the result of cirques floor analyses. Here we have positive values for plan curvature and a negative value for profile curvature. GLACIAL CIRQUES CURVATURE Param. Slope Plan Curvature Profile Curvature Max. Curvature Cirq. MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN A B C D Param. Min. Curvature Cross-sec. Curvature Long. Curvature General Curvature Cirq. MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN A B C D Table 1. Glacial cirques curvature amount FLOOR CURVATURE Param. Slope Plan Curvature Profile Curvature Max. Curvature Cirq. MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN A B C D

6 Param. Min. Curvature Cross-sec. Curvature Long. Curvature General Curvature Cirq. MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN MIN MAX MEAN A B C D Table 2. Glacial cirques curvature amount Cirques Curvature C. Floor Curvature Parameters Sign MEAN MEAN Plan Curvature + + Profile Curvature Max. Curvature + + Min. Curvature Cross-section Curvature /+ /+ Long. Curvature General Curvature /+ Max. Curvature Min. Curvature Plan Curvature Profile Curvature 99

7 Long. Curvature Cross-Sec. Curvature 5.CONCLUSION This research approach to identify and extract geomorphometric parameter of glacial cirques. Geomorphometry is the science of quantitative identification of terrain surface features by using digital elevation models. According to the expanded availability of spatial data, especially digital elevation models, methods to identify and mapping landforms based on geomorphometry increased. In this study, glacial cirques were identified manually and then geomorphometric parameter value, including plan curvature, profile curvature, min. and max. curvatures, long. curvature, cross-sec. curvature and general curvature were derived from the DEM of studying area. By analyzing obtained values seems derived curvatures are suitable parameters to identify quantitate features of landforms and make it possible for automated identification of landforms. REFERENCES Ahmadabadi, A., Sargsyan, V., Glacial Cirques Automated derivation based on geomorphometry features. Tehran, Khajeh Nasir Toosi University of Technology (KNTU). BLAGA, L., Aspects regarding the signifiance of the curvature types and values in the studies of geomorphometry assisted by GIS. Analele UniversităŃii din Oradea Seria Geografie, pp de Martonne, E., Sur la formation des cirques. Annales de Geographie, Volume 10, pp Desio, A., Sull'esistenza di piccoli ghiacciai nella Persia occidentale (Concerning the existence of small glaciers in western Persia). Bollettino del Comitato Glaciologico Italianao, Volume 14, pp Evans, I., 2006a. Allometric development of glacial cirque form: geological, relief and regional effects on the cirques of Wales. Geomorphology, 80(3), p Evans, I., 2006b. Local aspect asymmetry ofmountain glaciation: a global survey of consistency of favoured directions for glacier numbers and altitudes. Geomorphology, 73(1), pp Evans, I. C. N., Geomorphometry and the operational definition of cirques.. Area, Volume 6, pp Evans, I. C. N., The form of glacial cirques in the English Lake District. Cumbria. Zeitschrift für Geomorphologie N.F., Volume 39, p Ferrigno, J., Glaciers of the Middle East and Africa e glaciers of Iran. Satellite Atlas of Glaciers of the World,, Volume 1386-G-2, pp ,. 100

8 Grunert, J. C. H. P. C..., Rezente Ver-gletscherungsspuren in zentraliranischen Hochgebirgen. Eiszeitalter und Gegenwart, Volume 28, pp Moussavi, M. V. Z. M. V. F. S. M. R. Y., A new glacier inventory of Iran. Annals of Glaciology, 50(53). NCC, Digital Elevation Model (DEM) of Shahrekord Block, 10m Spatial Resolution Base on Topographic Map with Scale 1: 25,000, Tehran, IRAN: National Cartographic Center of. Pike, R., Geomorphometry diversity in quantitative surface analysis. Progress in Physical Geography, 24 (1), pp Preu, C., Die quartare Vergletscherung der inneren Zardeh-Kuh-Gruppe (Zardeh-Kuh- Massiv), Zagros/Iran, Augsburg: Augsburger Geographische Hefte 4. Rasemann, S. S. J. S. L. D. R., Geomorphometry in mountain terrain. In: Bishop, M.P., Shroder, J.F. (Eds.). In: Geographic Information Science and Mountain Geomorphology. Berlin: Springer, p. pp Seif A., E. B., Combined use of GIS and experimental functions for the morphometric study of glacial cirques, Zardkuh Mountain, Iran. Quaternary International, pp Vilborg, L., The cirque forms of Swedish Lapland. Geografiska Annaler Series A, Volume 59, pp Vilborg, L., The cirque forms of central Sweden. Geografiska Annaler Series A, Volume 66, pp Wright, H., Pleistocene glaciation in Kurdistan. Eiszeitalter und Gegenwart, Volume 12, pp Yamani, M., Geomorphology of Zardkouh glaciers. Geography Research (Iran), Volume 59, pp Zevenbergen, L. a. T. C., Quantitative analysis of land surface topography. Earth Surface Processes and Landforms, Volume 12, pp