Digul

Course

The river originates in the central part of the island, on the southern side of the Maoke Mountains (Digul or Star Mountains), which rise above sea level at 4,700 m. After leaving the mountainous section, it cuts through lowland swamps in a south-southwest direction and then flows by delta into the Arafura Sea, across Dolak Island. Its marshy, swampy floodplain is lined with reed beds. As there are no accessible and developed roads in the area, the river is still the only transport route across the marshes to the fertile hills and mountains in the interior of the island. It is navigable by larger boats from Tanahmerah (320 km) and by smaller boats from the foot of the mountains. This swampy navigable stretch is often referred to as Boven-Digul.

Geography and hydrology

Rising on the southern slopes of Maoke Mountains, the Digul flows first south and then west to empty into the Arafura Sea. For much of its length, it travels across a low region of extensive swamps and creates a delta near Dolak (Yos Sudarso Island, formerly Frederik Hendrik) Island. The river has a length of 853 km (530 mi) and is navigable as far as Tanahmerah. Together with the Mappi, which joins its northernmost delta, it collects the waters of an area of about 45,000 square kilometres.

The river flows in the southern area of Papua with predominantly tropical monsoon climate (designated as Am in the Köppen-Geiger climate classification) and tropical rainforest (designated as Af in the Köppen-Geiger climate classification) transitional type, with an annual rainfall of 3,500–4,000 mm.

History

The swamplands upstream were known by the name "Boven-Digoel" (Above the Digul, in Dutch) and hosted a penal colony at Tanahmerah (Red Earth) in the early 20th century, when Indonesia was a colony of Holland. As a result of the abortive 1926 revolt by the Communist Party of Indonesia (PKI), the Dutch exiled 823 of the most troublesome revolutionaries here.

Ecology

The Digul catchment has a rich and diverse fauna. Around 100 endemic species are found here (Paradisaea apoda, Ptilinopus perlatus, Chelodina novaeguineae, Centropus violaceus, Alcedinidae, etc.). The mud islands of the delta are covered with marsh and forest vegetation. The dominant species are mangrove (Avicenia alba, Rhizophora apiculata), mahogany (Xylocarpus moluccensis), nipa palm (Nypa fruticans), marsh plant (Bruguiera cylindrica) and their hybrids (Rhizphora mucronata).