Mamberamo

Hydrology

Its length from the confluence of the Tariku and Taritatu is 283 km (176 mi). From the source of the Waruta, it covers a total distance of 1,112 km (691 mi). It has a catchment area of 79,000 km2 (31,000 mi2) with an annual rainfall of 3,578 mm (Köppen climate classification classifies this area as type Af). Average width is 175–800 m (574–2,625 ft), depth 8 m (26 ft) (maximum 33 m).

History

In 1545, the Spanish navigator Iñigo Ortiz de Retes sailed along the northern coast of the island as far as the mouth of this river that he charted as San Agustín. At this spot, on 20 June 1545, he claimed the territory for the Spanish Crown, and in the process bestowed the name to the island (Nueva Guinea) by which it is known today.

The first European to enter the mouth of the Mamberamo was Dutchman Dr D. F. van Braam Morris in 1883. The residents from the northern Moluccas (Ternate) rowed up the river to ascertain that it was navigable by steamer. The following year in 1884 Van Braam Morris returned to the steamship Havik and travelled 60 mi (97 km) (as the crow flies) along its course.

Ecology and vegetation

The Mamberamo Basin is one of the most important biodiversity hotspots in New Guinea. Both Asian and Australo-Pacific elements are present in terms of botanical affinities. One survey at the foothills of the Foja Mountains identified 487 putative plant species, 156 of which are not assigned to known taxa, indicating a high proportion of undescribed species. The floodplain forests of the basin include swamp forests, seasonally flooded lakeside forests and sago forests.

Seven general vegetation categories are distinguished in the landscape: primeval forest (old-growth dryland forest), swamp forest (natural wetlands dominated by trees), lakeside forest (seasonally flooded forest), sago forest (a form of swamp) dominated by sago palm, secondary forest, mixed forest and sago woodland.

Geology

The region is geologically young (middle to late Miocene, i.e. less than 15 million years old) and remains tectonically active, with frequent earthquakes and landslides in the steepest areas. The mountain basin called "Mamberamo" is composed mostly of high floodplains, extensive swamps, forested wetlands, meandering rivers and backwater lakes. The sediment-rich rivers in the catchment belong to 'white-water' systems similar to the Amazonian moors. Three soil orders are present, of which the inceptisols are the most widespread, followed by ultisols and entisols. All soils are fine textured with poor drainage. The diversity of the region is a result of its geological history, which gives rise to a diversity of habitats.