Gurupa várzea

Gurupa várzea
Eastern Gurupa várzea (purple). Amazon river is blue and Xingu river almost black in this image
Ecology
Realm	Neotropical
Biome	Tropical and subtropical moist broadleaf forests – Amazon
Geography
Area	9,841.95 km2 (3,800.00 sq mi)
Country	Brazil
Coordinates	1°54′36″S 53°16′05″W / 1.910°S 53.268°W / -1.910; -53.268Coordinates: 1°54′36″S 53°16′05″W / 1.910°S 53.268°W / -1.910; -53.268

The Gurupa várzea (NT0126) is an ecoregion of seasonally and tidally flooded várzea forest along the Amazon River in the Amazon biome.

The Gurupa várzea ecoregion is named after the Ilha Grande de Gurupá, an alluvial island in the mouth of the Amazon. The várzea extends along the lower Amazon River from the mouth of the Tapajós down to the mouth of the Xingu River. It has an area of 984,195 hectares (2,432,000 acres). The Tapajós-Xingu moist forests lie to the south and the Uatuma-Trombeta moist forests to the north. The Monte Alegre várzea is upstream and the Marajó várzea is downstream along the Amazon.

In this region the whitewater Amazon is fed by the blackwater Xingú, Jari, and Tapajós rivers. Elevations are no more than 5 metres (16 ft). The Gurupa várzea contains floodplains along the river that are affected by daily Atlantic Ocean tidal fluctuations and seasonal flooding. At the height of the rainy season when the Amazon is in full flood water levels may fluctuate by 4 to 7 metres (13 to 23 ft) in a tidal period as the river water is dammed by the rising ocean tide. Outside the rainy season fluctuations may still be from 2 to 3 metres (6 ft 7 in to 9 ft 10 in) in a tidal period.

The region contains a complex maze of channels and sedimentary islands. The soil is made up of sediments carried from the eastern Andes by the rivers during the present Holocene epoch. The river sediments form levees along the margin of the river, behind which are areas of savanna on clay soil and open lakes. Both the savanna and the lakes flood daily, and the lakes grow much larger at the height of the flood season.