the plain and basin of the middle and lower course of the Irrawaddy River in Burma, between the Arakan Yoma on the west and the Shan Upland on the east.
The Irrawaddy Plain is an intermontane trough filled with marine and fluvial deposits (sandstones, argillaceous shales, clays). The northern part is a hilly, strongly broken plain with badlands and extensive development of erosional processes; the southern part is a flat alluvial lowland. The plain has a subequatorial, monsoon climate. The average temperature for January is 20°-23°C, and in May the average temperature is above 30°C. Annual precipitation totals 600–1,000 mm in the north and more than 2,000 mm in the south. (About 90 percent of the precipitation falls from June through October, during the southwest monsoon.) There are skeletal red-brown soils in the north and meadow alluvial soils in the south. The vegetation is dry savannas and monsoon deciduous forest, and in the delta, mangrove forests. Two-thirds of the territory of the Irrawaddy Plain is plowed up, and rice fields predominate (in the south). There are also plantings of millet, wheat, cotton, and oil-bearing crops.