Impacts of flood regimes on resource use in the Parana river delta (argentina): challenges and perspectives for the XXI century

CLAUDIO R.M. BAIGÚN; PRISCILA MINOTTI; PATRICIA KANDUS; RUBEN QUINTANA; RICARDO VICARI; ALBA PUIG; NORBERTO OLDANI

Lodz, Polonia

Congreso; Ecohydrological Processes and Sustainable Floodplain Management Opportunities and Concepts for Water Hazard Mitigation, and Ecological and Socioeconomic Sustainability in the Face of Global Changes.; 2008

International Hydrological Programme UNESCO and InterAcademy Panel Water Programme

The Paraná Delta region is a huge mosaic of rivers and wetlands which stretches through the final 300 km of the Paraná River, covering 17,500 km2. These wetlands exhibit rich terrestrial and aquatic biodiversity, highly adapted to annual hydrological cycles. Historically, livestock, wildlife and fish were exploited in a sustainable way. In the last years, however, flood intensity, amplitude and variability have decreased due to the combined effect of flow regulation by dams in the upper basin, waterway drainage works on the main channel and new road infrastructure crossing the region, promoting new scenarios for resource use. Forest plantations have developed by draining marshes and building polders. Cattle numbers have steadily increased from some 50,000 to more than a million, changing the seasonal cycle to year round grazing , due to a combination of persistent dry conditions enhanced by high soy bean prices which expelled livestock activities from nearby mainland areas. The sabalo (Prochilodus lineatus) fisheries tripled, encouraged by export revenues and lack of adequate regulations, promoting overfishing with a strong reduction in fish biomass and mean individual size. In addition, residential projects are encroaching on areas close to urban centers, filling natural wetlands but opening artifical lakes and channels. We review how these changes are impacting the Delta ecosystem functioning, its biodiversity and resource sustainability, compare past and present riverscape uses in terms of goods and services, and discuss possible outcomes for foreseen climate change scenarios.