All chapters:

Introduction

Climate

Waters and water management

Ecosystems and ecoregions

Species diversity and use of biological resources

Nature conservation: econet and protected areas

Countries & cultures

Economy

Land use

International policy

(See map Topography of Amur-Heilong River Basin). 

The Amur-Heilong is the largest river basin in northeast Asia.  It flows eastwards from the Mongolian Plateau through Mongolia, China, Russia and covers a tiny bit on North Korea at Songhua River headwaters.The Amur-Heilong River is one of the world’s largest free-flowing rivers and, at approximately 4,444 kilometers in length, is the ninth longest river in the world.  At approximately two million square kilometers, it is also the world's eleventh largest watershed (see Table).  The largest tributaries of the Amur-Heilong River are the Zeya (Russia), Bureya (Russia), Amgun (Russia), Songhua (China), and Ussuri/Wusuli (China, Russia).  The river forms the border between China and Russia for over 3,000 km, making it one of the world’s longest border rivers.  The Upper Amur-Heilong Basin includes the Mongolian headwaters and Argun/Erguna River basin, the main stem of which flows for more than 900 kilometers and forms the China-Russia border.  The main stem of the Amur-Heilong River proper is often referred to as a river of three reaches, Upper, Middle, and Lower.  The Upper and Middle Amur are shared by Russia and China.  The Lower Amur lies completely within Russia and stretches 947 km from the mouth of the Ussuri River to the estuary of the Amur-Heilong River.

The terrain of the Amur-Heilong River basin is largely mountainous.  Mountain ranges, ridges, foothills, and plateaus cover two-thirds of the region.  Most mountains are low, ranging from 300 to 1,000 meters in elevation.  Only isolated mountain ranges and peaks, covering just over seven percent of the territory, reach elevations exceeding 2,000 meters.  The major mountain ranges situated along the Okhotsk Sea coast reduce the influence of monsoons on inland areas during the summer and autumn.  Similarly, the mountain ranges that extend from east to west along the northern border of the basin form a barrier that reduces the influence of arctic air masses in winter.

Three wide (300 to 500 km) and parallel bands of mountain ranges cross the Amur-Heilong basin in a more or less north-south direction.  The Great Hinggan (Da Xing’anling) Range spans the upper reaches of the Amur-Heilong River.  The Small Hinggan (Xiao Xiaoxing’anling) and Bureya Ranges cross the center of the basin.  Furthest downstream, the Sikhote-Alin Range separates the Amur from the Pacific Ocean near the Tatar Strait and the Sea of Japan.  An even wider mountain system, the Stanovoy and Tukuringra-Dzhagdy ranges, extends in a nearly east-west direction along the northern border of the basin.  The Changbai Mountains, an isolated outcrop located entirely in the Chinese part of the basin, mark the extreme southeast extent of the basin. The highest point in the Mongolian basin is Asralt Peak in the Henti Mountain Range (2,452 m) and the lowest point is the Khokh Lake depression (560 m) in the Uldz River basin.

The area covered by plains is also large.  Extensive, hilly steppe plateau occupies the south-west part of the basin in Mongolia, Russia, and Inner Mongolia.  The main plains and lowlands are located between the Zeya and Bureya Rivers, near Khanka Lake, in the valley of the Lower Amur, at the confluence of the Amur-Heilong with Songhua and Ussuri Rivers (Sanjiang Plain), and in the middle reaches of the Songhua at the confluence of the Nen and Second Songhua Rivers, which drain the Song-Nen Plain.  Geological research in the Middle Amur-Heilong and the Song-Nen plain suggests that several huge, shallow lakes covered these areas millions of years ago.  Lacustrine fine sand deposits often underlie the contemporary soil surface.  After the lakes receded, sand was blown into dunes that supported only sparse vegetation..  These areas are also unusually rich in dinosaur fossils.

The basin is rich in biological diversity and supports thousands of species and many ecosystem types.  This vast area is famous for rare waterfowl, big cats, and endemic fishes.  The biological richness is explained by a great diversity of landscapes such as  steppe, floodplain wetlands , alpine tundra, mixed broadleaf-coniferous forest, and boreal taiga.