Simulation of cross-sectional variations of the Pilcomayo River channel, Paraguay

The Pilcomayo is a very active sand-bed river located in South America, where during the last decades, quick changes in cross-sectional shape and dimensions have been observed. The total amount of sediment transported by the river is around 140 millions of tons per year, being one of the largest in the world (Martín-Vide et al., 2014). Due to hydrological regime, the flood season is from January to March, with a maximum discharge around 4600 m3/s. However, the monthly average flow during floods is 650 m3/s. During the dry season, the river is almost dry, with the minimum measured discharge being 1.5 m3/s. The bed is formed by fine sand (Fig. 1), with a median size D50 equal to 100 μm. Wash load is formed mostly by silt and clay and represents the 89% of the total amount of sediment transported by the river. The high variability of flows and the presence of a highly erodible bed made of fine sand makes the Pilcomayo a very active river with cross-sections responding very fast to the flow.