Ussuri River

　　The Ussuri River is a tributary of China's Heilongjiang (Amur) River and serves as the border between China and Russia. Its upper reaches are formed by the confluence of the Ulao River and the Daobi River. Both rivers originate from the southwestern slopes of the Sikhote-Alin Mountain Range, flowing northeast to Khabarovsk (formerly known as Haerbin), where they join the Heilongjiang River. The Ussuri is 909 kilometers (565 miles) long, with a drainage basin covering 187,000 square kilometers (72,200 square miles). The river is wide, and its flow is relatively slow. Major tributaries include the Songacha River, the Muling River, and the Naoli River. A long section of the main course was once the subject of a Sino-Soviet border dispute (1969), and in 1977, both sides established navigation rules for the international waters. The Ussuri River remains frozen for about five months each year. Navigation is possible downstream from the mouth of the Ulao River.

　　　The Ussuri River is a major right-bank tributary of the Heilongjiang River and an important boundary river along China’s northeastern border with Russia. Its upper reaches are formed by the convergence of the Ulao River and the Daobi River, which then flow northeast before sharply turning southwest near Khabarovsk and emptying into the Heilongjiang River. The Ussuri is 880 kilometers in total length, with a drainage area of nearly 190,000 square kilometers. This includes the stretch from where its tributary, the Songacha River, joins, to the point where the Ussuri meets the Heilongjiang River. The river has both eastern and western sources: the eastern source originates from the western foothills of the Sikhote-Alin Mountains in eastern Russia, flowing from south to north, while the western source, the Songacha River, rises northeast of Xingkai Lake, which is its only outlet. The 492-kilometer section from the Songacha River, through the main course of the Ussuri, to where it joins the Heilongjiang River, forms the China-Russia border. The river’s drainage basin spans 187,000 square kilometers, of which 61,500 square kilometers lie within China’s Heilongjiang Province.

　　　　The entire course of the Ussuri River flows through the vast longitudinal valley between China’s Wandashan Mountain Range and Russia’s Sikhote-Alin Mountain Range. Most of its river sections run across flat plains and traverse low-lying wetlands and marshes. Only a midstream section within Raohe County features occasional proximity to low hills and ridges along the riverbanks.