Natural and human impacts on the landscape evolution and hydrography of the Chico River basin (Argentinean Patagonia)

Abstract

We aimed to assess how geomorphological processes during the Cenozoic, including those triggered by human intervention, modeled the landscape and affected the hydrography of the Chico River basin (Argentinean Patagonia). We analyzed the hydrography, mapped the geomorphology, and propose a landscape model of the study area. We found the Chico River basin geomorphology, drainage surface, and hydrological regime were affected by Paleogene and Neogene tectonic uplift, Pleistocene glaciations, Holocene climatic change and also, the human impact. We described four different stages (Early to Late Pliocene; Early to Late Pleistocene; Early to Middle Holocene; Middle Holocene to present) of the basin hydrography and drainage surface. The main conclusion is that the current boundaries of the Chico River basin were established after the mid-20th century. Formerly, the Chico River was the downstream extension of the Senguer River basin (located northwest of the study area), with both rivers forming a single system. However, prevailing arid climatic conditions since the Middle Holocene together with the climatic variability and anthropogenic activities during the last century produced the current disconnection between the Chico and Senguer river basins. Consequently, the Senguer River basin has changed from exorheic to endorheic, and the Chico has turned into an intermittent river.