This paper analyses the impact and degradation of some Brazilian large rivers as Paraná, Tocantins, São Francisco and Teles Pires rivers, showing the need of restoring their natural characteristics and floodplain.

Restoration of large rivers has been practised in some countries. The experience of Germany, United State, United Kingdon and Denmark are important examples. Restoration of large rivers in the sense of the return to the original condition is still a big challenge because it is extremely complex, expensive and the background to predict success or to monitor recovery is little (Gore and Shields, 1995).

In Brazil, both regulation and channellization have modified channels. As in other parts of the world, these experiences have destroyed or degraded most river environments and the fish and wildlife habitats once provided by the rivers and their floodplain wetlands.

River regulation has been applied to hydroelectric power generation and the country has around 65 rivers regulated by plants above 10MW. Hydropower is the main primary source of renewable energy (62.07%) followed by wood (21.39%) and sugarcane (16.53%).

River regulation has been implemented in relation to both large and medium-size rivers. The Southeast and South of the country are the main areas of regulated rivers because they are the principal developed areas of the country and have good environmental conditions, including favourable land and rivers inclination. These areas include the large Paraná River and its tributaries, some secondary rivers that run to the Atlantic Ocean and the headwater of São Francisco River. A small number of rivers have been regulated in the Northeast of the country and only recently, towards the end of the 1970s and 1980s, has the government tried to produce hydropower energy in the north of the country. Included in these projects are the large Tocantins and Tapajós rivers and the medium-size Curuá and Ji-Paraná rivers.

River channellization has been effected in many lowland rivers for the proposes of irrigation projects, flood protection (rural and urban areas) and to improve the health of the population by doing away with malaria and yellow fever. All the main lowland rivers in the Northeast and Southeast of the country were channellized during the 1970s and 1980s and recently, agro-cattle-raising projects have led to some rivers in the centre-west of the country, such as the Araguaia and São Lourenço rivers, being channellized. Rivers in the Amazon basin have been protected from channellization.