EARTH SURFACE PROCESSES AND LANDFORMS, VOL. 19,777-787 (1994) GPS, GIS AND GEOMORPHOLOGICAL FIELD WORK S. C. CORNELIUS zyxwvut Department zyxwvutsrqpon of Environmental and Geographical Sciences, The Manchester Metropolitan University, Manchester, U. K. D. A. SEAR Department zyxwvutsr of Geography, The University of Southampton, Southampton, U.K. S. J. CARVER School of Geography, The University of Leeds. Leeds. U.K AND D. I. HEYWOOD Department of Environmental and Geographical Sciences, The Manchester Metropolitan University, Manchester, U.K. Received 10 January 1994 Revised 26 May I994 zyxwvut ABSTRACT This paper introduces the Global Positioning System (GPS) and considers its role as a technique for use in geomorpho- logical field work. Although valuable on its own, it is apparent that the utility of GPS in geomorphology is enhanced when used alongside Geographical Information Systems (GIS) technology in the field. This paper reviews GPS, con- sidering what it is, the methods available and their relative accuracies, the potential and problems of the technology and its relationship with GIs. Particular attention is given to the application of GPS in geomorphological and related case studies. Examples are presented of the successful use of GPS and GIS to study hydrology and snow patch regime from the recent GeoAltai expedition to Southern Siberia. KEY WORDS Global Positioning System Geographical Information Systems GLOBAL POSITIONING SYSTEM Overview The use of Global Positioning System (GPS) technology is becoming rapidly more widespread throughout disciplines with a requirement for geographical information. From its origins in the American military, the use of GPS has spread to the point where it is widely recognized as a tool for the rapid creation and updating of geographical databases. GPS is described by Barnard (1992) as a set of satellites and associated control systems that allow a suitable receiver to determine its location anywhere on earth 24 hours a day. They are all-weather systems which offer varying degrees of accuracy and include the Russian GLONASS and the U.S.A.'s GPS. It is the GPS system which is discussed here. GPS is based on the constellation of 24 NAVSTAR (Navigation System with Time and Ranging) satellites, four of which are visible at any time from any point on the Earth's surface (Lang and Speed, 1990; Barnard, 1992). The full operational configuration is expected by late 1994 (Yunck, 1993). Each satellite transmits two carrier signals at frequencies of 1575-42MHz (known as L1) and 1227.60 MHz (L2). These carriers are phase modulated by binary code signals which contain time informa- tion, termed C/A (coarse acquisition) and P (precise acquisition). Each satellite has unique C/A and P codes. z 0 1994 by John Wiley zyxwvutsrqp & Sons, Ltd. CCC 0197-9337/94/090777-11