Morphodynamics of the Parana River in the light of climate change

The work highlights the sediment dynamics that takes place at different scales along the Middle and Lower Parana River (Argentina), by means of different numerical models. The principal aim of this study is to provide a multi-disciplinary and multi-scale approach to predict the future river’s morphodynamics in the light of climate change. This approach may be applied to evaluate the long-term impact of the river’s morphodynamics on anthropogenic structures and activities over or nearby the watercourse (i.e., bridges, levees, navigation way). The study was realized by using three different levels of detail of mathematical modelling. Climate models give the input ensemble, i.e., future precipitation and temperature over the La Plata Basin. The VIC hydrological model simulated the flow discharge time-series, which were then used as input for an own-developed 1-D hydro-morphodynamic model. This 1-D code was able to simulate future rate of sediment transport and corresponding bed-level changes at watershed scale and provided the initial and the boundary conditions for a more detailed 2-D model. Therefore, future evolutions of a specific part of the main and the secondary channels were simulated with the MIKE21C code, developed by the Danish Hydraulic Institute. The performed analysis indicated a rather low sensitivity of the Middle and Lower Parana River bed profile to the relevant increase forecasted in flow discharge, whereas the channels appreciably divagates. In particular, variability increase rather than averaged value of predicted discharges appeared effective in driving current bifurcated morphology into a meandering-multithread pattern.