Sepik

The Sepik is a massive river system on the island of New Guinea. It is the longest river on the island. In the Oceania region, it ranks as the third largest river by discharge volume. This refers to the amount of water the river carries. The Fly and Mamberamo rivers are larger in this regard. Most of the river flows through the Sandaun and East Sepik provinces of Papua New Guinea. A small section flows through the Indonesian province of Papua.

The river's journey begins in the Victor Emanuel Range. These are high mountains in the central highlands of Papua New Guinea. From these headwaters near Telefomin, the water travels north-west. It leaves the mountains abruptly near Yapsei. The river then flows into Indonesian Papua. After that, it turns north-east to follow the great Central Depression. It winds in a serpentine fashion, which means it curves like a snake. This winding path continues until it reaches the Bismarck Sea. Unlike many large rivers, the Sepik has no delta. A delta is a landform at the mouth of a river. Instead, it flows straight into the sea near Wewak.

The Sepik has a massive drainage basin of over 76,000 square kilometers. This is the total area where water collects and flows into the river. The river itself is over 1,100 kilometers long. Its bed is wide and averages a significant depth. Along its course, the river creates a vast floodplain. This floodplain can be up to 15 kilometers wide. This area contains extensive backwater swamps. There are about 1,500 oxbow lakes in this floodplain. An oxbow lake is a U-shaped body of water. The largest of these are the Chambri Lakes. The river carries an annual sediment load of 115 million tonnes.

Many different tributaries feed into the Sepik. A tributary is a smaller river that joins a larger one. The Yuat River is a major tributary. It is formed by the Lai and the Jimmi rivers. Other tributaries come from the Bewani and Torricelli Mountains. They also come from the Central Range to the south. The river's environment is largely undisturbed. There are no major urban settlements in the catchment. There is also no large-scale mining or forestry. This makes the system a very important freshwater wetland. It is possibly the largest uncontaminated freshwater wetland in the Asia-Pacific region. However, many fish and plant species were introduced after the mid-20th century.

Human history is deeply tied to these waters. Local villagers have lived here for many millennia. The river provides food, transport, and culture. There are at least 100 distinct villages and hamlets along the banks. The river basin is home to many language families. These include the Torricelli, Sepik, and Lower Sepik-Ramu families. The Iatmul people are the largest cultural group. They call the river Avusett, which means "bone lake."

European contact began in 1885. This was after Germany took control of the northeast part of New Guinea. The ship Samoa was the first European vessel to enter the estuary. The explorer Otto Finsch named the river Kaiserin Augustafluß. He named it after the German Empress Augusta. Later, Leonhard Schultze used the name Sepik for the whole river. He noted other names like Azimar. An explorer named William Churchill noted that many local groups had different names for small stretches. He believed there was no single indigenous name for the entire stream. After World War I, the German name faded. The name Sepik became the official designation.

Scientific interest in the river grew through various expeditions. In the early 20th century, groups like the Südsee-Expedition visited. They studied local tribes and collected plants and animals. They also produced the first maps of the region. The town of Angoram was established in 1913 as a base. After World War I, Australia took control of the territory. They established a station at Ambunti to continue explorations. In 1923, a journalist named Beatrice Grimshaw traveled the river. She was the first white woman to ascend the Sepik. The river remains a vital part of the region's geography and culture.