Brazilian Matogrossense swamplands (Pantanal Matogrossense) are a plan, lowered, swampy surface of 138-183 Km2, inside high Paraguay basin on west centre region of Brazil. It encompasses partial areas from Mato Grosso (MT) and Mato Grosso do Sul (MS) States. Paraguay river and tributaries control typical pattern forms: fragile fluvial dikes, floodplain lacustrine forms and extensive fluvial fans. Sub-basin surfaces connect themselves water, sediments, nutrients during main flood periods (from November to March). Between Descalvado (MT) and Corumbá cities (MS), along Brazil/Bolivia border (north-south direction), there is a depression zone (bajada), on quaternary sediments between fans, with extensions along downstream from tributaries Corixa Grande, and Cuiabá (MT State); Taquari, Negro, Miranda (MS State). These drainage control fans and define their floodplain over bajada's zones resulting in residual lakes, oxbow lakes, terraces, flood plains and abandoned dikes. Singular drainage pattern occurs on variable superposed directions and meandering channels inside silted braided plains. They reflect successive regional structures and flow regime changes. There is a new fan of Paraguay River, between Descalvado and confluence of Cuiabá River (alluvial material).

Extensive fans are constituted by sediments from Pantanal Formation, distinct period of flooded duration between themselves and on their segments higher to interior. There are alluvial-coluvial cones of 'piemont' around fans, near high relieves. Fans are in construction process, over local depressions, through flood plain expansions.

Artificial changes of channel, on fluvial-lacustrine environment in formation along Paraguay River, become inappropriate with insufficient studies and legal preservation areas: Taima Biologic Reserve and Matogrossense National Park, with archaeologic sites around Descalvado and Taima Isle, for example. It is necessary much attention on monitoring Paraguay fan area.