Chaguar

Abstract: Bermejo River Basin is located in the Chaco Plains in northern Argentina (Fig 1). The river has an extension of 1,450 km and the basin area covers 16,048 km2, comprising the north of Salta and the Formosa and Chaco provinces. Its principal tributary is San Francisco River which carries mountain waters. Two different sections can be detected in Bermejo River: the upper and the middle-low Bermejo. Vegetation is wooded with more plains to the east and with the presence of isolated yungas. Vast areas have been historically inhabited by indigenous communities with extensive farming practice. Not taking into account further agricultural colonization, traditional productive activities in the dry Chaco were based on the supply of forest resources and rivers: timber and firewood, cattle grazing and goats, hunting and commercial and subsistence fishing, and harvesting of fruits (carob, mistol), fibers (chaguar) and honey. Nowadays, economic activity is typically agricultural and it is located in two main centres separated by a large plain: east of Salta and east of Chaco. Moreover, historical data show that the region has been the scene of frequent hydrometeorological disasters (floods and droughts) and the impacts of these events have had a strong impact on the welfare of the population, productive activities and infrastructure. Fifty years ago, agricultural enterprises were risky. Today they are a tool for development and a forcing factor for vulnerabilization of productive instruments and traditional living. There is ample evidence that climate change impacts are already being observed today and that policies that seek the best ways to meet them are essential for the development and welfare of the community. Therefore, the Argentinean Chaco is a region that, as a result of the change in land use, presents “hotspot "or critical areas for the period 1982-1999 (Baldi et al 2008; http://lechusa.unsl.edu.ar /). They are the result of the implementation of deforestation for the advancement of agriculture and intensive farming. In this region the climate is subtropical with a mean annual rainfall cycle showing a minimum in winter, which is more pronounced in the west, with dry conditions prevailing from May to September (Gonzalez and Barros 1998, Reboita et al 2010). The Andes chain lies along the west of Argentina and prevents the access of humidity from the Pacific Ocean. Therefore, the flow is governed by the South Atlantic High and as a consequence, winds prevail from the north and the east. An intermittent low pressure system, whose origin could be a combination of thermal and dynamical effects, is located between 20o and 30oS, in a dry and relatively high area east of the Andes. This system is observed all year long, though it is deeper in summer than in winter. When this low is present, northerly flow is