CONICET | Buscador de Institutos y Recursos Humanos

Adaptive management at proper scales of unstable water resources is critical in semiarid regions, particularly when long meteorological and hydrological data series are scarce. This precludes differentiation of superimposed local, regional and global trends, resulting in erroneous short-term policies based on a rationale derived from main shifting environmental baselines, either occurring or remembered by most stakeholders, such as the recurrent floods of the last 3 decades in the Argentinean Pampa. As presented here, the wet phase from 1970 -2007 produced a dramatic area increase of the coastal, brackish Chasicó Lake, resulting in loss of agricultural land, complete submersion of a touristic village and danger of flooding of large neighbouring saltworks. Simultaneously, reduction of lake salinity produced a drastic biomass increase of the commercially important fish Odontesthes bonariensis. Generalized misperception of flood hazards led managers to propose measures focused exclusively in the reduction of such impacts. However, recent studies on historical records strongly suggest the current onset of a dry phase that could last 25-50 years. This can lead to an increase of lake salinity beyond tolerable limits for its fish population; increased estuarine salinity and reduced freshwater availability for direct human consumption, agriculture and industry. This could induce a socio-economical collapse in a region with recurrent freshwater shortage due to infrastructure weakness and paradoxically, strong industrial development. Several solutions have been proposed for the management of Chasicó and adjacent basins. We discuss main approaches, their advantages, shortcomings and conflict potential in changing scenarios from multi-decadal wet to dry periods.