Saturday, 20 March 2010

Mahakam River

The Mahakam River is in Indonesia. It flows 980 km from the district of Long Apari in the highlands of Borneo, to its mouth at the Makassar Strait.

The city of Samarinda, the provincial capital of East Kalimantan, lies along the river 48 km (30 mi) from the river mouth.

Mahakam Lakes

There are about 76 lakes spread in the Mahakam river basin and about 30 lakes are located in the middle Mahakam area including the three main lakes (Lake Jempang 15,000 Ha; Lake Semayang 13,000 Ha; Lake Melintang 11,000 Ha). The lakes levels are seasonally fluctuated from 0.5m – 1m during dry period to seven meters during rainy season. The Mahakam lakes and surrounding wetlands act as a trap of sediment contained in the water flowing into the lakes which are now known to become shallower, presumably as a result of an imbalance between sediment input and slow subsidence.

Fishing is the primary source of livelihood in the Mahakam lakes area, most of the people around the lakes are fishermen. The middle Mahakam lake area is an area of intensive fishing activity with a productivity of 25,000 to 35,000 metric tons per year since 1970.

Mahakam Delta

The Mahakam delta is a mixed fluvial-tidal dominated delta. The delta covers about 1800 km2, consisting of mangrove areas near the shore, Nypa swamps in the central areas, and lowland forest near the apex, corresponding to the first bifurcation, however, recent fishery development in this area has converted a vast area of mangrove into shrimp ponds (tambak). The delta has three main distributaries system directed Northeast, Southeast and South. The area between distributaries consists of a series of tidal channels generally unconnected to the main distributaries.The distributary channels are narrow and rectilinear with the depth ranging from 8 to 15 m and distributary channel bifurcations appear every 10 to 15 km.

This lower Mahakam area is the second most productive hydrocarbon basin of Indonesia which contains around 3 billon barrels of oil and 30 Tcf of gas reserves. Field geological investigations in this area was started in 1888 and in 1897 exploration drilling discovered oil at shallow depth of 46 m on the Louise structure. Production started in 1898 followed by expansion of exploration to the entire Mahakam.

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