Online system, http://www.scar.ac.cn Sciences in Cold and Arid Regions 2009, 1(2): 0151 –0156 Barchans of Minqin: quantifying migration rate of a barchan ZhenTing Wang 1,2* , Hui Zhao 1 , KeCun Zhang 1 , XiaoZong Ren 2 , FaHu Chen 2 , Tao Wang 1 1. Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China. 2. CAEP, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Lanzhou University, Lanzhou, Gansu 730000, China. *Correspondence to: Dr. ZhenTing Wang, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Lanzhou University, Lanzhou, Gansu 730000, China. Tel: +86-931-8912329; E-mail: wangzht@lzu.edu.cn Received: 23 December 2008 Accepted: 8 February 2009 ABSTRACT The migration speed of a typical barchan on the border of Minqin oasis, Gansu Province, northwestern China, was estimated by means of two methods. One is on the basis of a simple physical model and short-term field measurements. The other comes from the combination of the barchan internal structure detected by ground-penetrating radar and optical/radiocarbon dating techniques. The upper limit of migration speed given by conventional C-14 dating is 3.42 m/yr. The optically stimulated luminescence dating indi- cates that the time-average migration speed of the studied barchan was 1.78 m/yr in 28 years prior to 2007. The physical estimation further suggests that the annual migration speed has increased in recent years. Keywords: barchan; migration; sand flux 1. Introduction The determination of migration speed is of general interest in understanding barchan dynamics. To date, three main approaches have been taken to deal with this problem. (1) Long-term field investigations including aerial and morphological surveys appear to be the most reliable method and are widely applied all over the world (Finkel, 1959; Long and Sharp, 1964; Hastenrath, 1967, 1987; Gay, 1999). Such investigations require a long time, several years at least. For example, 34 bar- chans on the west side of Salton Sea had been observed for 15 years (Long and Sharp, 1964). (2) The barchan migration speed can also be calculated on the base of short-term field measurements and some physical as- sumptions (Bagnold, 1941; Ahmedou et al., 2007). It is often assumed that barchans migrate without changing their shapes. (3) Recently, Bristow et al., (2005) and Bristow and Pucillo (2006) presented a preliminary ap- proach that combines ground penetrating radar (GPR) and optically/infrared stimulated luminescence (OSL /IRSL) dating to identify and date dune migration rates. Minqin basin is located on the lower reaches of Shi- yang River, east of Hexi Corridor in Gansu Province of northwestern China. It adjoins Tenger desert and Badain Jaran desert. The Minqin oasis, with an area of 14,400 km 2 , is situated in the central section of the basin. At present, it is regarded as a typical region in which rapid desertification is occurring (Wang et al., 2008). A de- tailed description of the Minqin oasis has been made (Zhang et al., 2005). Previous studies of barchans in this region showed that: (1) the height of slipface is propor- tional to the width of horns, and the baseline can be roughly described by parts of an ellipse and a parabola (Wang et al., 2007); (2) the sand flux increases with the arc length of the brink first and then decreases at both low and high wind speeds (Wang et al., 2008). In this