Spatial Modeling of Climatic Parameter Fluctuation Mapping Temperature Variation in the Bermejo Basin from 1901 to 2000 Martín de Zuviría MaxSys Engineering GIS/RS Scientist. 176 Rideau St, Ottawa, ON K1N9P1, Canada. Tel: (613)789-2606; Fax: (613) 789-0078. E-mail: mdezuviria@sympatico.ca  Osvaldo F. Canziani Co-chair, IPCC Working Group II. Ave. R. Scalabrini Ortiz 1978, 1425 Buenos Aires, Argentina. Tel/Fax: (54-11)4831-7864. E-mail: ocanz@ciudad.com.ar Introduction The Problem Understanding the spatial and temporary variations in climate within a zone, and their relationships with other factors, like topography and geographic location, is important in activities related to climate change and the management of the natural resources, such as land-use planning, watershed management and territorial ordering. Even when these variations are sometimes reported in maps, the values represented there are presently often obtained by the straight application of subjective criteria, seldom supported or replaced by the systematic use of computerized techniques of spatial data analysis and modeling. On the other hand, the scarce use of these techniques has limited largely not only the possibilities to map the temporary variations of climatic parameters, but also to assess their spatial relationships with other environmental factors. Objectives The main emphasis in this study is on presenting a method for mapping and analyzing the temporary variations of climatic parameters linked to the global climate change. This method focuses on the use of Geographic Information Systems (GIS) and the development of a georeferenced database, and is applied in producing air temperature and thermal zones temporal variation maps of the Bermejo Basin, in northwest Argentina, and in assessing their spatial relationships with land-cover types. The Argentinian Sector of the Bermejo Basin The Bermejo Basin, shared by Argentina and Bolivia, is part of the macro-region of the Plata Basin. It embraces a surface area of 123,162 km2 and its main watercourse has a length of more than 1,300 km (Strategic Action Program for the Binational Basin of the Bermejo River, 2000). This study is done at a reconnaissance scale 1: 500,000 on the argentinian sector of Bermejo Basin, covering about 90% of its total surface. This sector embraces portions of the provinces of Chaco, Formosa, Jujuy and Salta, between 22 and 27°S, and 58 and 66°W. Because of its characteristics, the Bermejo Basin is divided into the Upper Basin and the Lower Basin. The Upper Basin is located in the west, between 300 and 5,700 m.a.s.l., in the Eastern Range of the Andes and the Sub Andean Ridge, where the dominant relief is undulating to very steep (area represented in Figure 3). The climate presents a sharp rainfall gradient, from 2,200 to 200 mm annually, with high seasonal variations, while mean temperatures decrease with elevation from 23°C to below 0°C in the higher mountains. The (semi)natural vegetation varies from closed and exuberant forests in the lowlands, between 300 and 1,500 meters, to woodland shrubs, open grasslands and sparse cactus deserts in the highlands, above 1,500 meters. The main land-use varies from dry-land farming in the highlands, to forestry and livestock in the lowlands with irrigated and rain fed agriculture in the lowest sectors. Living conditions show extreme variations with broad sectors having a precarious economic existence. The Lower Basin is located in the east, between 40 and 350 m.a.s.l., in the Chaco Plain, where the dominant relief is flat to very flat. Annual rainfall varies from 1,500 mm in the east, with moderate seasonality, to 700 mm in the west, where seasonality is sharp. Annual mean temperatures vary from 21 to 24°C, showing poor relation with elevation. The (semi)natural vegetation varies from grasslands, forests, and swampy herbaceous communities to shrubby mosaics. The main land use is forestry and livestock, with important sectors under rain fed agriculture and smaller areas under irrigated agriculture. In general, population density is low to very low and living conditions extremely precarious.
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