Towards a classification of the delta systems in transitional semi-arid Chile between the rivers Copiapo and Aconcagua

Abstract

In the last decades countries like Chile have been faced with swift and growing territorial transformations, principally derived from the process of agricultural modernization and urban expansion, as in those zones favoured in climatic terms for the production of «specialized» agriculture where semi-arid regions have shown important comparative advantages. In this paper a proposition is presented for the incorporation of determining factors (like the morpho-edaphologic vulnerability, morfo-climatic position and the corresponding level of intervention, in conjunction with physical geographic variables) in the taxonomic classification of delta systems. In order to reach this goal, three catchments have been selected: those of the rivers Copiapó, Choapa and Aconcagua, which are representative of different phases of agricultural modernization, and of the interior and costal urban expansion, located in differing morfoclimatic environments, ranging from marginal desert, through the semi-arid, to the transitional belt in the temperate zone. According to this analysis, a discussion is proposed on the limits suggested by (ArayaVergara, 1981) to classify estuaries, the following criteria have been taken into account: i) morpho-climatic position, ii) processes and current dynamics of inlet system, iii) current landforms, iv) geodynamic processes of the catchments, v) level of intervention into the catchments. Therefore, a new classification of the studied delta systems is here proposed: Rio Copiapo: paleo delta, stabilized morphology, arid environment with high basin intervention; Rio Choapa: truncated delta, dominated by waves and fluvial energy, morphologically dynamic, semi-arid environment with low basin intervention; Rio Aconcagua: delta dominated by waves and fluvial energy, morphologically dynamic, semi-arid environment with high basin intervention.