Pantanal is an alluvial lowland region in western border of Brazil. The Paraguay is the trunk river of a depositional system tract composed of several humid alluvial fans. The Taquari alluvial fan, the most conspicuous among then, is a giant wet system with circular geometry and 250 km in diameter. Its altitudes varies from 160 m at the fan apex to 100 m at the fan toe (gradient of 24 cm / km).

The present channel system is slightly entrenched in the upper fan. Here, the Taquari River is a meandering channel and sedimentation occurs in a confined meandering belt. This pattern changes downstream as a consequence of progressive narrowing of the meandering belt, as well as decreasing of sinuosity and height of terraces.

In the middle fan the system acquires a radiating distributary pattern. Many points of avulsion, progradation and abandonment of crevasse splays are visible in satellite images. The water discharge decreases downstream mainly by avulsion and secondary by infiltration and evaporation.

Active avulsions and anabranch confluences characterise the distal part of the river, where the active fan lobe is being constructed. Multitemporal analysis using satellite images, obtained in the last 30 years, revealed abrupt changes in the river course. The main avulsion point, called "Arrombado Zé da Costa", is nowadays responsible for 70% of discharge, shifting the Taquari main course.

Avulsion and shifting are natural phenomena in the evolution of the Taquari alluvial fan, but are now accelerated by human occupation. Agricultural activities have increased erosion in the drainage basin and sediment imput to the alluvial fan. In consequence, the Taquari River is being rapidly filled up with sands, causing shallowing and navigability problems, triggering avulsion and enlarging floods in the lower fan.