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

Climate

Nearly two thirds of the basin's precipitation falls in the three months from June to August.  May and September are transitional months and the dry season extends for seven months, from October until April during which precipitation is only 15% of the annual total.  Floods occur annually during the short three-month wet season, a period during which 84% of the big storms occur.  Even so, water is in short supply throughout most of the basin during the much longer dry season.
Snow cover is only 1-21 cm thick in the Mongolia basin, allowing for year-round livestock grazing.  During the warm season, 247 mm or 94% of annual precipitation falls as rain, while almost 14 mm or 6% of total precipitation falls as snow in the cold season.  Local climatic variations here are extreme and this promotes diverse vegetation types from semi-desert to taiga forest.  Downstream, but yet in the upper Amur-Heilong, precipitation ranges from 400-500 mm.  Total precipitation in the middle reaches of the Amur-Heilong increases to 500-700 mm.  Annual precipitation on the continental plains of the China basin is 450-600 mm.  Snowfall is modest and snow cover rarely exceeds 20 cm.  The shallow snow cover allows soils to freeze to depths of 2-4 meters.  Most snow sublimates before spring melt due to the dry atmosphere and intense solar radiation.  In humid areas of the Lower Amur-Heilong and Ussuri-Wusuli Rivers precipitation is abundant, exceeding 700-800 mm.  Although typhoons are infrequent, they can bring rains of up to 400 mm in a single day.  Rainfall accounts for 60-75% of annual precipitation, starting from 20 May to early June in all parts of the region, and ending during the last ten days of September.  The lower Amur and Okhotsk seacoast are among the most snow-rich areas of the world, with 1-2 meters of snow cover by the end of winter.  Some valleys accumulate 3-4 meters.